The Roboutian Heresy

by Zahariel

Inspired by the great Dornian Heresy of Aurelius Rex, here is an alternate timeline to the Warhammer 40000 universe, where Guilliman turned traitor instead of Horus, and led half the Legions in rebellion against the Emperor. The Index Astartes are done for all Legions. Now, the Times of Ending have begun ... Also has a TV Tropes page now !

12. Index Astartes : Ultramarines

I do not own the Warhammer 40000 universe nor any of its characters. They belong to Games Workshop.

Inspired by the Dornian Heresy, by Aurelius Rex.

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Index Astartes – Ultramarines : The Fallen Paragons

In the bygone days of the Great Crusade, the Thirteenth Legion was a symbol of all that Humanity could achieve, and the Five Hundred Worlds of Ultramar an example for all humans across the galaxy. But the lies of Chaos found their way into the heart of Roboute Guilliman. At the heart of the Archenemy's kingdom, the Primarch of the Ultramarines fell into darkness, dragging his sons with him. Dark forces blinded his eyes to the light of the God-Emperor, making him embrace the madness that is Chaos. Ten thousand years have passed since the end of the Heresy he ignited across the Imperium, and while the body of the Arch-Traitor lies in state at the heart of his ever-burning empire, his vile deeds echo unto eternity. Hated even by the rest of their damned kin, broken by the fall of their adored liege, the Ultramarines are trapped within the Ruinstorm by the Iron Cage. Yet despite all that has befallen them, they yet plot and scheme to bring about a new age of damnation across the galaxy. For the Ultramarines belong to Chaos, and the Dark Gods are ever hungry …

Origins

Though the Dark Gods often appear divided and capricious, elevating or casting down their champions on a whim, they are also capable of patient plotting and schemes that spread across decades. It is important that we remember this, as it is all too easy for Inquisitors to see the blood-crazed cultists and the screaming berzerkers of the Traitor Legions and forget the malign intelligence that directs all slaves of Chaos. The tale of Roboute Guilliman and the Ultramarines is a powerful reminder that the Ruinous Powers are far from mindless Warp-born nightmares screaming into the void for the destruction of all that is pure. When they work in concert, there is very little that they cannot either bring to their service or cast down in flame and ruin.

In the ten thousand years that followed the fall of the Emperor and the death of Roboute Guilliman, many Imperial potentates have struggled to erase all knowledge of the Arch-Traitor. Even among the Holy Ordos, the truth about the Accursed Thirteenth and its primogenitor are reserved only for the highest-ranked Inquisitors. Very few texts regarding the past of Guilliman have survived the passage of time and the purges of the archives. While this can be regretted, as it leaves us with precious information on one of the greatest enemies of the Imperium, there are still enough traces left to reconstitute the path that led Roboute Guilliman from being one of the greatest Primarchs to the worst danger the Imperium ever faced.

After the Dark Gods stole the Primarchs from the Master of Mankind, one of them landed on the world of Macragge, in the galactic Eastern Fringe. Once the seat of power in an empire that spanned hundreds of star systems, Macragge had endured the Age of Strife relatively well, though its galactic glory had long passed. Its people had managed to preserve much of the lore of the Age of Technology, and were even capable of short-range Warp travel, which enabled them to keep in contact with a handful of other systems. The riches of the world were plentiful enough to prevent the ruthless exploitation that has ruined the ecosystem of so many worlds, and it was devoid of any native predators that could endanger its population. Still, the planet was divided between rival nations, and political and military feuds were common.

There, the life-pod was found by a group of noblemen on a hunting expedition. The leader of the group, named Konnor Guilliman, recognized it as a piece of advanced technology, and when he saw the perfectly formed baby inside it, the unmarried, childless man decided to adopt him into his household. After bringing the child back to his estate in the city of Magna Macragge Civitas, the greatest power on the planet, he named him Roboute, and began raising him as his heir.

What little is known about Roboute's foster father depicts him as an honorable man, dedicated to the people of Macragge and the prosperity of the kingdom to which he was one of two Consuls – an office of supreme authority which was, to avoid the rise of a tyrant, shared by two men at all times. Under the best tutors his father's wealth and prestige could procure, the child quickly grew both strong and wise, learning all that others had taken years to master in a matter of weeks.

But Konnor's integrity was not shared by all his colleagues in the power structure of Macragge City, and as Roboute neared his fifteenth year, his father's co-Consul, a man named Gallan, began to plot. Gallan knew of Roboute, and he feared the young giant's power even more than he feared Konnor's political and military might. Gallan was an ally of the state's old aristocracy, whose power had been steadily decreasing ever since Konnor's rise to power and his promulgation of more and more progressive laws. These nobles, whose wealth rested on the near-slavery of thousands of indentured workers, refused to see their centuries-old control of Macragge escape their grasp, but they did not dare strike while there was chance that Roboute might stand against them.

It was a tradition for Macragge's ruling elite to send their young men off to war when they became of age, so that they would learn the values of a soldier and help expand the dominion of the city-state. Gallan arranged for Roboute to be sent in the north of Macragge, to the land of Illyrium, from which tribes of barbarians had raided the territory of Magna Macragge Civitas for generations. It was a most dangerous assignment, but one Roboute willingly accepted, for he feared no mortal man, and was eager to prove his worth to his foster father and the rest of the people of Macragge.

As would have been expected, Roboute quickly distinguished himself in the north, earning the respect of both the men fighting alongside him and the tribes themselves. His fighting prowess was admired by the proud savages, and several tribes willingly submitted to him, joining side with those they had raided for centuries in return for the honor of fighting at the side of a warrior such as Roboute. Soon, a vast portion of Illyrium was under his control, and the leaders of the remaining tribes had called for negotiations in order to join this new province, rather than face him in battle.

Roboute stopped mid-speech as the entrance to the tent was suddenly slapped open, admitting a man clad in pitted armor, his flesh pale and covered in sweat, with feverous eyes that locked onto the son of Konnor at once. The super-sensitive nose of the young lord could smell blood and smoke on the man, and his keen eyes noted that, beneath the armor – which didn't really fit him, and bore more traces of blood, as if he had taken it from a corpse – the newcomer wore the tunic of one of Macragge City's messengers.

The man stumbled toward him, the chieftains and sub-commanders instinctively giving him space. He finally crashed on his knees before Roboute, out of breath. Despite his obvious exertion, he forced himself to look up, and spoke words that would haunt Roboute for decades to come :

'The city … is burning … your father … needs you … my lord …'

But just as Guilliman was starting the meeting that would hopefully bring peace to a quadrant of the world that hadn't known it for centuries, word reached him from Macragge City. Civil war had broken out in the ancient city. Mobs were rampaging through the streets, the Senate had been burned to the ground, and Konnor's estate was under attack. Enraged, Roboute postponed the negotiations and led his army – both the professional soldiers from the city and the warriors who had joined him in the north – back to Magna Macragge Civitas.

After several weeks of travel at full speed, he found the city still burning, though more than two months had passed since the beginning of the hostilities. Forces loyal to the republic were fighting against blood-crazed mobs and rebellious forces, but there were no lines of battle, no ordered regiments clashing against each other. For countless years, war on Macragge had been considered a science, even sometimes an art : even the barbarian tribes of the north had their own savage code of honor, forbidding the murder of non-combatants and other depraved acts of war. Yet now the people saw the true face of that hideous beast. Already tens of thousands were dead, killed by sword, bow, or burning alive in their homes as they were consumed by the flames set off by arsonists. Absolute chaos reigned in Magna Macragge Civitas as looters, thugs and rapists roamed the streets, with only a few pockets of order holding out against the insanity of it all. Konnor's estate itself was besieged by hordes of armsmen, reinforced by brigands brought from the wilderness around the city by the promises of gold and plunder.

The sky was red, the light of the fires reflecting on the black clouds that emanated from the burning city.

Roboute had come here many times in the past. This place, atop one of the hills surrounding Magna Macragge Civitas, gave a view of the great city that had never failed to make him wonder at the magnificence that Mankind had achieved on this world.

Now, it showed him what had happened in his absence. The poorer quarters had suffered the worst – most houses there were made of wood and not of stone, and the fires had spread the most quickly there. But the rich quarters had been the ones most targeted by the looters, and even now Roboute's ears could pick up the sounds of battle as the rioters fought what few survivors hid there as well as each other. The great rotunda, where the senators of Macragge had gathered for hundreds of years, had been reduced to fire-blackened rubble, and the great libraries were spitting clouds of ash into the night as the wind passed through their destroyed doors.

And there was something more, something that tugged at his subconscious. Something that …

The messenger. He had claimed to have left the city as soon as the rioting began, but upon seeing the extent of the desolation, Guilliman suddenly realized that the numbers didn't add up. They had rushed back here as fast as possible, killing many beasts of burden and leaving many of their slowest units behind in the process. Even a professional army, in full control of the streets, would have been unable to raze the colossal city in such a short time … and yet there was barely a building remaining standing in Magna Macragge Civitas.

A cold sensation ran down his back as he contemplated matters darker than even the blackened sky, and he felt as if he could hear the sound of cruel laughter in the screams of the dying city.

Enraged, Guilliman stormed through the city and toward his father's domain, tearing to pieces all who dared to try to stop him. Even as fury threatened to overcome him, however, he remembered his duty, and ordered his trusted commanders away from his own advance, tasking them with restoring order across the burning city. But it was far too late – the journey back to the city had taken too long. When he arrived to the estate, Roboute found nothing but burned out ruins, and the desecrated cadaver of his foster father. It is said that the young Primarch found the head of his father on a pike where the doors of the mansion had once stood, left there as one last insult to the man by his murderers.

While the death of his adoptive father was a terrible blow to Roboute, far more terrible were the news that his nurse, a woman named Euten, was among the dead. She was the one who had cared for him in the few years he had spent as a child, effectively his surrogate mother – a gift few of the Primarchs ever had. Her demise caused him great personal sorrow, and is believed to have been the catalyst for the string of executions that Guilliman ordered once the riots had been put down and order restored.

Through thorough interrogation – some might say torture and point at this as the start of Guilliman's downfall, though all members of the Inquisition deal in worse things at some point in their service without being consumed by the Ruinous Powers – Roboute quickly reconstructed what had happened. Gallan and his cohorts had attempted to kill Konnor at the Senate, after ensuring most of his guards would be busy dealing with the riots. They had known that Roboute's foster father would immediately send his men to quell the chaos in the streets rather than see to his own safety, and they had used his selflessness against him. Yet even so, they had failed at their assassination attempt, and Konnor had managed to retreat to his estate. Then, while the nobles' armed troops clashed against each other, the drunken mobs had gone out of control, and the whole city had gone up in flames.

Not a single one of the ringleaders behind the riots and the attack on Konnor's estate was spared. They died not by the sword or poison, as was their right as noblemen, but hung like common criminals, in full view of the vengeful populace, who acclaimed Roboute as his father's successor and the rightful ruler of Macragge Civitas. Yet he was ruler of a ruin, for almost nothing remained of the city's infrastructure, and with winter approaching, time was short if a famine was to be avoided. Using his gift for logistics and the well-supplied stores of the executed nobles, Roboute managed to see his people through the winter, and began rebuilding what had been lost. Under his control, Macragge Civitas rose from the ashes of its destruction stronger than ever. Tribes from the north came to replace the losses in population, bringing with them their warrior traditions.

In the years that followed, Guilliman brought all of Macragge under his control. With ruthless political acumen, he made the other noble houses of Macragge Civitas follow his leadership, and led a rapid campaign of extension. By means both diplomatic and military, he united all of the nations on the planet. Technologies which had been previously jealously guarded by the noble caste were instead spread out and studied, and Macragge entered a new golden age. Once the whole world was under his control, Roboute turned his attention towards the other worlds that had once been part of the old Kingdom of Ultramar. Declaring that Kingdom reborn, Roboute pursued his campaign among the stars, bringing world after world into the embrace of his fledgling star empire through the same mix of diplomacy and military conquest that had served him well on his adoptive homeworld.

Thirty years after the unification of Macragge, Roboute ruled over more than a hundred worlds, and his borders were rapidly expanding. It was as he was returning to Macragge after another successive campaign that the Emperor finally reached His son's adoptive homeworld, His fleet emerging from the Warp at the edge of the system, sending greetings toward the planet.

During the Great Crusade, the Emperor had been looking for His lost sons, finding them one by one and reuniting them with the Legions He had created in their images. How He was able to search for them in the immensity of space is unknown – many believe that He could trace their presence in the Empyrean somehow – but it is known that the Master of Mankind had known the location of Roboute for years before they finally met. However, a powerful Warp Storm around Ultramar had prevented the Imperial ships from reaching the Primarch, and the Emperor had been forced to wait for them to dissipate. In hindsight, it is likely that these storms were created by the Archenemy, as part of their plot to eventually turn Roboute against his father.

At first, it seemed that tragedy was about to strike, as Macragge's fleet and orbital defenses reacted to the sudden appearance of such a massive number of unknown vessels by preparing to fight. But the Emperor reached out to the people of Macragge, claiming that He was looking for His son and meant no harm to them. Accepting to meet, Roboute recognized his father at once when he laid eyes upon Him. The two of them discussed the Emperor's plans for the galaxy and Mankind's place within it, and Roboute agreed to add his Kingdom to the Imperium and take command of the Adeptus Astartes Legion that the Emperor had created from his gene-seed. He insisted, however, that Ultramar remain under his own control, at least for the time it would take to properly integrate it into the greater Imperium. The Emperor accepted, seeing it as the best way to bring more than a hundred worlds into His domain without bloodshed. However, this acceptance would end up having dark consequences.

The Great Crusade

'You are more than warriors. Warriors fight for glory, for personal power and wealth – at best, they fight for what they believe is right, forcing their own ideals upon those around them. You have sacrificed everything on the alter of Mankind's destiny, to serve the ideals of the Great Crusade and help create the Imperium. You are part of a whole far greater than the sum of its parts.

You are also more than soldiers. Soldiers fight because they had ordered to. Sometimes it is because they trust those giving them orders, other times because they have no choice but to obey or face punishment. But you follow me because my blood flows through your veins, and you follow your commanders because they are your brothers.'

Roboute Guilliman, upon taking command of the Thirteenth Legion

Upon being reunited with his sons, Roboute named them "the Ultramarines", in what many saw a sign of arrogance and dangerous provincialism. But the Emperor allowed it, as a reward for what His son had achieved before being reunited with Him, and that was the end of the argument. The first thing he did with his newly gained armies was to continue the expansion of the Kingdom of Ultramar, learning how to best deploy Astartes while bringing world after world into the embrace of his galactic fiefdom. Under Guilliman's rule and with the aid of the Imperium's resources and technology, the Five Hundred Worlds became one of the most prosperous regions of the Imperium, bringing thousands of regiments of the Imperial Army to the Great Crusade.

Like several other Legions, the recruits used during the Thirteenth's creation came from all over Terra – but in their case, it was only geographically the case. While some other Legions took aspirants from all ways of life, the Thirteenth was formed of the children of these tribes which had resisted the Unification the most harshly, often to the bitter end. Thousands of children were taken from the refugee camps where the last of these tribes' people remained, effectively condemning many of them to extinction. Though this might appear ruthless, this move ensured that the potential seeds of rebellion would be removed before they could grow, and integrate the vigor and war-like nature of these tribes into the Imperium's service. However, in hindsight, it might also have been one of the reason why so many veteran Ultramarines were ready to rebel against the Emperor. In the other Traitor Legions, most ancients opposed the rebellion, but that wasn't the case when the Thirteenth was concerned. It is possible that, despite all the conditioning that was part of their induction, some part of them might have remembered the fate of their mortal families.

'Hatred feeds on itself, growing ever stronger as the grudges pass from one generation to the next. As Astartes, it is your duty to break that vicious cycle. We bear the hatred of those we force into compliance, and stand so far above their reach that revenge cannot even be considered. In that way is the cycle of hatred broken.'

Attributed to Primarch Roboute Guilliman

When Roboute took command, the flux of recruits began to come almost exclusively from Ultramar. The firsts to join the Legion were the descendants of the tribes that Guilliman had brought with him from the north when he had marched on Macragge Civitas. For decades, they had been his personal enforcers, those of his forces that he trusted above all, and they quickly proved themselves among the Ultramarines. The sheer size of the Kingdom of Ultramar allowed the Ultramarines to have both quantity and quality in their recruits, and the numbers of the Thirteenth Legion quickly soared even as their tally of victories continued to increase.

However, a dark mood remained on the Legion. Guilliman knew that his sons still bore the scars of an event that had occurred before he took command : the Osiris Cluster Rebellion.

A few years before Guilliman met the Emperor, the Thirteenth Legion was deployed to the Osiris Cluster, where the human population, which had been peacefully integrated into the Imperium years before, had suddenly risen in rebellion. The Astartes had prepared a strike on the world of Septus XII that would slay the leaders of the rebellion and hopefully force the rest of the population into submission, but when they launched their attack, they discovered the true nature of the Osiris Cluster Rebellion. The population hurled itself at the Legionaries with dead eyes and makeshift weaponry, uncaring of the losses the Space Marines inflicted. While the Legion's elite was locked in battle with an enemy that outnumbered them a ten thousand to one, the true foe revealed itself as a fleet of hourglass-shaped xenos warship entered the battle. The mind-controlling aliens that would come to be called the Osirian Psybrids had finally joined the fray.

The Osirian Psybrids

Many were the horrors of the Long Night, when the Warp Storms bred by the decadence of the Eldar Empire and the rise of psykers isolated human worlds from one another. During the Great Crusade, these ancient threats were crushed mercilessly beneath the Emperor's boot, but only at great cost. The xenos lifeforms known as the Osirian Psybrids were one such threats, and their power was immense.

The Psybrids were tall but thin creatures, clad in bio-mechanical suits of armor, that breathed a combination of gases toxic to any human. Their physical form was barely material, instead half-way between corporeal and gaseous. They communicated by telepathy, though no human psyker was ever able to understand their inhuman minds. Each of them possessed tremendous psychic power, which probably derivative from their diet : the living brains of sentient beings. They could break the will of most sentient beings, turning them into empty-minded puppets, and unleash warp-fire upon those of their foes who could resist them.

One shudders to imagine how a species with a diet such as the Psybrids could come to evolve on any world of the galaxy, but despite the best efforts of the Imperium's researchers, their origin remains a mystery. When the Imperium encountered them during the Great Crusade, they were a nomadic species, living in their great voidships as they journeyed from world to world. To sate their appetite, the Psybrids ravaged countless civilized planets. Each time their methods were the same : first, they brewed chaos and disorder among their prey through their mind-control abilities. Then, once their target was weakened, they took a more direct approach, enslaving as many of the population as they could before revealing themselves. Those who could resist their influence – those with even a spark of psychic potential – were captured and brought to the xenos' ships, where their brains were the finest delicacy. It is unknown how many human worlds were lost to their depredation during the Long Night, as there is little to differentiate their atrocities from those of any number of other predatory species. But the Psybrids did not only target Humanity : all sentients were prey to them. Even the Eldar, who at the time ruled the galaxy with an unchallenged grip, lost some of their number to the Psybrids' hunger. Had the Fall not brought the children of Isha to ruin, there is little doubt that the might of their empire would have been brought to bear against the Psybrids in time.

In the ensuing chaos, Lord Commander Gren Vosotho, the Legion Master of the Thirteenth since its foundation, had been slain, alongside most of the Legion's veterans. The chain of command was decimated, and young Chapter Master Marius Gage ended up in command. He ordered a withdrawal from the Septus system, but the Osirian Psybrids still had an ace in the hole : the brainwashed forces of the Imperial Navy in the Cluster, which ambushed the retreating Legionary vessels. By the time the Thirteenth reached safe territory, almost a third of its forces had been lost in the most devastating defeat ever suffered by a Legion at this point in time. To worsen the damage to the Legion's morale, by the time they returned to the Osiris Cluster with appropriate equipment and reinforcements, the worlds had become mass graves, filled with the corpses of the Psybrids' discarded servants.

Ever since that disaster, the Thirteenth Legion had been seeking the Osirian Psybrids, thirsting for revenge. But despite all the resources at their disposal, their search had been in vain, and the sense of humiliation festered in their hearts, breeding shame and anger. The Primarch of the Ultramarines knew that the only way his sons could be purged of their past was to find and destroy the Psybrids once and for all. Finding the xenos was part of that goal, but it would only be of use if they had a plan to destroy the creatures.

So Roboute threw himself into the study of what little was known of the Osirian Psybrids. A handful of corpses had been collected in the battle of Septus XII, and with the Primarch's authority, they were released from the Mechanicum's care to be studied in person by the Legion's father. From these lifeless bodies, the Primarch deduced the likeliest way their minds worked, and from the tactical data, he extrapolated their reasoning and cultural bias. Roboute also conversed with his Librarians at length, and asked them to search the Warp for any psychic trace of the Psybrids. Finally, soon after the reunification of the Five Hundred Worlds was completed, a lead presented itself. The Psybrids had been seen in the Eurydice system, where a force of the Twelfth Legion had been battling the Orks which had come from a nearby Ork empire to raid and destroy Imperial settlements. An astropathic message from the War Hounds' commander, cut short by Warp interference, warned the Imperium of the appearance of the tell-tale hourglass-shaped ships, and asked for reinforcements.

The full might of the Ultramarines was gathered to answer that call for help, though the sons of Guilliman gave little thought for their cousins' fate, so obsessed were they with the prospect of avenging their dead at last. When they arrived, they found that the Psybrids had come to the system to enslave the Orks, and had already managed to seize control of nearly half of the present Waaagh ! while the other half fought furiously against its own brethren and their puppet masters, who had been reinforced by more of their own ships as well as others from a variety of xenos species, all enslaved to the will of the Psybrids. The whole system was filled with warships fighting one another, the Orks showing surprising cohesion when faced with the Psybrids' threat. The War Hounds were found on one of the system's moons, where their ship had crashed after being shot down by the Psybrids' weapons, and despite their leader's insistence that they be part of the offensive, they were denied and sent back to their Legion aboard one of the smaller ships of the fleet. This was Ultramarines business, and the Avenging Son intended for his forces to deal with it alone.

With overwhelming strength, Guilliman's fleet forced its way through the ships of the Orks, both enslaved and free-willed, and reached the Psybrids' own vessels. With the Primarch himself leading them, the Ultramarines began one of the greatest boarding actions ever performed in the history of the Legions. They brought the battle aboard the Psybrids' ships, leaving a trail of devastation in their corridors, destroying life-support systems and the infernal machinery that kept their stocks of still-living heads alive for consumption. At the heart of the greatest ship, Guilliman himself fought against the leader of the xenos, a creature of near godlike power recorded in the archives of the Thirteenth Legion as the Psybrid-King.

The Primarch stood alone against the creature, bleeding from a dozen wounds taken on his way to this particular chamber. The toxic atmosphere of the Psybrid vessel was pouring into his armor through the rents that had been opened in it by the xenos' attacks, but Roboute's enhanced physiology was keeping their effects at bay.

Baleful fire was engulfing him, even as he struggled to get closer to his titanic foe so that he might tear it down with his power gauntlets. Each step closer to the creature was more agonizing than the last, and he could feel the heat spreading through his body as his metabolism worked overtime to repair the damage to his flesh almost as soon as it was inflicted. But despite his defiance, despite the fact that would not – could not – stop, the bitter truth remained obvious :

He couldn't defeat the Psybrid-King. Unlike his brother Magnus, his talents laid not in warp-craft, but in tactics and logistics, and they were useless to him now. His warriors had been killed on his way to this place where he had deduced the enemy leader must be, his handful of Librarians slain one by one by the aliens' superior psychic might. Alone, with nothing to shield him from the creature's powers, he could feel even his mind begin to buckle under the pressure of the Psybrid-King's mental assault.

He needed power, power of a more brutal, direct kind than that which he already possessed. He needed …

Something burst in his mind, like some dam finally breaking, releasing a great flood that had so far been contained. With a scream of agony, twin arcs of blue lightning shot out of the Primarch's eyes, encompassing his body in a protective bubble that repulsed the xenos' attacks. With a roar of primal pain and fury, Roboute resumed his charge, and the two Gauntlets of Ultramar pierced right through the ethereal body of the Psybrid-King, killing the creature instantly. As its corpse tumbled to the floor, Roboute fell to his knees, his hands raised to cover his face while his mind whirled with the implications of what had just happened.

And even as he considered what to do now, he heard, as if from a great distance, a familiar laughter …

After the death of the Psybrid-King, the rest of the Osirian xenos quickly succumbed, many of them struck down by some psychic ill as their leader fell. As the Ultramarines returned to their ships, the xenos vessels were bombarded relentlessly for hours, the whole fleet on the lookout for any escape craft trying to flee the devastation. Once no life-sign remained in the Osirian vessels, Guilliman ordered them to be dragged and thrown into the system's star, erasing any trace of the creatures' existence. Even as they executed the orders of their liege, the Ultramarines felt the wound on their pride heal as their hated foe was not just defeated, but utterly exterminated. When they fell upon the remaining Orks, it was with a vigour and a sense of purpose they had not known since the battle of Septus XII. Their victory after so long brooding over their losses at the Psybrids' hands reinforced the loyalty and esteem of the Thirteenth for its Primarch considerably. Thousands of Ultramarines died in the operation, but the threat of the Osirian Psybrids was wiped out forever – there has never been any contact with Psybrid survivors since the Battle of Eurydice.

That event left a mark on Roboute. He had witnessed the true horror that the Emperor sought to protect Mankind from with the construction of the Imperium, as well as the power lurking within the Warp. Determined that his Legion would be capable of fighting such threats in the future, he gave greater importance to the Librarium of the Ultramarines, increasing its size and the authority of its members.

With the honor of the Thirteenth Legion restored by the Psybrids' extermination, the Ultramarines returned to the Great Crusade with renewed fervour, determined to prove their worth to the gene-sire that had wiped out their shame. In the following decades, thousands of worlds were reclaimed by the sons of Guilliman, often with little civilian losses. Guilliman's mastery of diplomacy was passed on to his Legion, and most Chapter Masters of the Ultramarines thought it their duty to only use strength to bring compliance to a human world when all other options had already failed. Though this method took more time than outright conquest, the sheer number of Ultramarines in existence allowed the Legion to accumulate a tally of compliances few others could match.

Many in the Imperium saw the Ultramarines as the greatest of the Space Marines Legions, the one embodying the ideals of the Great Crusade above all others. Of course, none were foolish enough to say so where other Legionaries could hear them, but the Ultramarines were aware of their standing and some of them flaunted it in the face of their cousins. When Alpharius was found and the Alpha Legion joined the Great Crusade openly, it is said the Guilliman mocked his youngest brother by claiming that Alpharius would never be able to match his own tally of conquests. This humiliation is believed to have been the cause for Alpharius turning to darker methods of conquest, until Konrad Curze set him back on the right path. But though the youngest Primarch would come to see the wisdom of the Saviour of Nostramo, the antipathy between Guilliman and Alpharius would endure.

Other Primarchs were put off by the Ultramarines' superior attitude. Angron and Perturabo, who knew war to be an ugly business that had nothing glorious about it, were uneasy when they saw the parades and war celebrations of the Thirteenth. But apart from them, Guilliman was held in high esteem by his brothers, who saw the Five Hundred Worlds as an example of what the Imperium could be : ordered, prosperous, and dutiful. Yes, the Ultramarines were proud, but they were hardly alone in that, and were these not times one could rightfully be proud to be part of ?

When, after two hundred years of leading the Great Crusade from the front, the Emperor announced that He would return to Terra, Guilliman was surprised. Like all Primarchs, he had assumed their father would oversee the Great Crusade to its glorious end, when all the stars were held in Man's unchallenged grip. But what really angered Guilliman was the choice of Horus to replace the Emperor as the leader of the Great Crusade. Roboute respected and loved his brother – as was said many times, it was impossible not to love Horus. But he saw the First Primarch as more of a champion, a being of great power and grandeur that was suited to win epic victories, but less suited to the management of thousands of smaller operations at the same time. Roboute believed that he would have been a better choice as the Warmaster, and he made his opinion known during the Triumph of Ullanor. Still, the Emperor didn't budge on His choice, and Guilliman reluctantly bowed to his father's decision.

Though the conflict between Guilliman and his father had occurred in private, the Avenging Son still felt humiliated by Horus being elevated above him. While submitting his Legion to Horus' authority, Guilliman chose to take his own personal force, the 12th Expeditionary Fleet, on a journey to unknown space, away from Horus' control. The Warmaster authorized it, believing that his brother merely needed time for his anger to cool off and the wound to his pride to heal. But neither of the two Primarchs knew just where Guilliman's travels would lead him : to the very gates of Hell, and beyond. For Guilliman had set course toward the uncharted regions of the galactic core, and his path would bring him to the ill-famed world of Cadia.

The Shadow of Cadia

Cadia, the Gate of Hell

First discovered by Mankind during the First Exodus, Cadia stands at the threshold of the spatial anomaly known across the entire galaxy as the Eye of Terror. Its skies are tainted violet by the nearness of the Warp Storm, and any human born on the planet's ground has pupils of the same color, even if the mother arrived on the world literally minutes before giving birth. After decades of experiments, the Inquisition has concluded that this mutation does not damage the soul of the carriers in any way. However, Cadia's human population is also subject to a rate of mutation far superior to that observed in the rest of the Emperor's domain, even on the other worlds forming the Iron Cages.

Cadia sits in the path of the only known stable Warp route out of the Eye of Terror. While there are countless other paths out of this cesspool of damnation, all of them are either unstable, temporary, too small for a fleet to pass through, or any combination of the three. The only way for a united fleet to leave the Eye of Terror and unleash a Black Crusade upon the galaxy is through the Cadian Gate. For that reason, the planet is the crown of the Iron Cage surrounding the Eye. Thousands of Iron Warriors and hundreds of thousands of Imperial Guardsmen defend it at all times, and not a single year passes without at least one engagement, either against Chaos raiders attempting to slip through, or against one of the many cults on the planet itself. A dozen Inquisitors of the Ordo Hereticus are permanently stationed on the planet, but even they struggle to prevent heresy from engulfing the world.

By all rights, the planet should have been engulfed into the Eye of Terror long ago. It is believed that the reason why it remains in realspace is the thousands of pylons of unknown origin that are scattered across its surface. One kilometer tall and half-buried beneath the planet's surface, these devices keep the tide of the Warp at bay, but cannot stop its influence completely. The Ordo Xenos has studied them for centuries, but does not dare perform experiments that could disturb them and risk the loss of Cadia to the tides of the Eye.

Despite centuries of investigation, there is only one known account of what happened when the 12th Expeditionary Fleet arrived in the Cadian System. As was only fitting for an Expeditionary Fleet commanded by a Primarch, many remembrancers accompanied the 12th, and one of them wrote his (or her, for we have never uncovered the remembrancer's identity) version of the events. In later years, when the galaxy burned with the first of Roboute's Heresy, this text would be leaked to the Imperium, casting some light over the events that led to Guilliman's fall to Chaos. Through this text and the Thousand Sons' divinations, it has been possible to reconstitute most of what happened.

No one knows what motivated Guilliman's decision to go to the galactic core, out of the hundreds of destination he could have picked that would have put him out of Horus' reach. Perhaps he came upon ancient records from the Dark Age of Technology, which spoke of colony ships being sent to this region of space, and hoped to bring more human populations to the fold of the Imperium. But it is clear that the Dark Gods guided him, with his knowledge or not, for when his fleet finally emerged from the Warp after a long and difficult journey, they were ready for him.

Cadia had become infested with creatures from the Warp, which had all but entirely consumed the planet's human population. The moment the Geller fields of the fleet went down, astropaths and Librarians alike began to scream as they sensed the evil that had overwhelmed the planet. They had met such things before, during the Great Crusade : on worlds where alpha-level psykers had lost control of their powers and burst apart, creating gateways into the Warp from which psychic predators emerged. Cadia was a world of abominations, and Guilliman ordered his fleet to advance toward the planet so that it might be purged from orbit. The humans that remained on the world couldn't be saved – there were literally billions of Warp-born creatures on Cadia – but the Ultramarines could at least put them out of their misery.

However, even as the fleet prepared to enact Exterminatus, another fleet appeared in the system, far beyond the Mandeville point and right in the middle of the Imperial formation, outnumbering the hundred vessels Guilliman had brought with him almost three to one. These ships were twisted horrors, ancient hulks from a dozen cultures lost to the Warp over the ages and reshaped by the dark powers that dwell there. According the the psychically-sensitives among the Imperial fleet, they were crewed not by mortal beings, but by creatures from the Empyrean. Their weapons didn't fire shells of metal or rays of laser, but the unholy energies of the Warp and swarms of void-flying Neverborn. Immediately after their appearance, they engaged the Ultramarines and their allies.

Guilliman reacted quickly to this new threat, commanding his fleet to move against the abominations in their midst, devising patterns of attacks on the fly. But the daemonships could jump in and out of the Warp at will, avoiding being surrounded and making the usual approach of the Ultramarines to void warfare completely irrelevant. Then, the daemonships sent boarding parties on the Imperial vessels, destroying many of them when their Astartes guardians failed to protect the vital sections of their ships.

Even as Guilliman was fighting against the Neverborn which had manifested aboard his flagship, the Macragge's Honour, he directed his fleet, somehow figuring out the patterns in the Warp-born armada's vanishing tricks. He commanded his ships to fire at empty space, only for the shells to hit straight into daemonships that had just re-materialized.

That laugh, thought the Primarch. I know that laugh …

The leering voice of the creature came from everywhere and nowhere as Guilliman fought his way across the sea of twisted flesh and malformed bones. It echoed in his skull and burned his soul.

'Yes, Roboute. It is I. Do you remember me ? When last we spoke, I was disguised as one of your mortal servants, warning you about all that you had lost … The look on your face when you learned about it was priceless !'

Roboute tried to locate the origin of the voice even as he continued to advance through the ocean of Warp-born beings. Despite his inhuman hearing, he failed : the voice registered to his senses as if coming from every shadow around him.

'It was so easy. I whispered in their ears, telling them what they wanted to hear, and they listened. They were so eager, so hungry for power and wealth, like all humans. I spurred their instincts, drove the beast within all of them into a frenzy … in the end, I didn't even have to force any of their hands. They did it all willingly, while you were fighting to protect them. The third one you had executed, do you remember him ? I must confess, I forgot his name. But I remember that he was the one who killed that pitiful creature you called a mother.'

'You will die for this,' the Primarch growled as he crushed another creature with the Gauntlets of Ultramar. 'And before that, you will suffer. I swear it ! Name yourself and face me, daemon !'

After near half the daemonships had been reduced to flaming hulks of corrupted steel and tainted flesh, the entity commanding the daemonic armada made itself known to the Primarch. Reaching through the Warp to touch Guilliman's mind, it presented itself as Be'lakor, Firstborn Son of Chaos and Master of Shadows.

Be'lakor, the Master of Shadows

Little is known of the Daemon Prince that claims the name of Be'lakor, even by the highest echelons of the Ordo Malleus and the hallowed Grey Knights. Those who attempt to investigate his nature are often discovered insane, dead in their studies, or simply vanish and are never heard of again, all of their research gone or destroyed. What little lore has been preserved remains on Titan, beyond even the reach of the self-proclaimed Master of Shadows.

Be'lakor is incredibly ancient, even by the standards of immortal daemons. Traces of his influence have been found in the ruins of alien civilizations that went extinct millenia before Mankind first left Terra – and it probably isn't a coincidence that they died out soon after the Master of Shadows reached out to them. He is even believed to be the first Daemon Prince : the first sentient being to have ever been transformed by the Dark Gods, shedding his mortality to become an immortal lord of the Warp. According to this theory, he was elevated by the four Ruinous Powers in concert, and for a time used the fact that he was the only one of his kind at his advantage, gaining more and more power in return for the services he performed for the Dark Gods. But soon, as is their way, the Dark Gods grew bored and sought new toys – toys which would be wholly theirs, and not shared with their brothers. They elevated new Daemon Princes, and Be'lakor power waned as the energies of Ruin were no longer condensed within a single vessel.

Despite this weakening of his powers, Be'lakor remains one of the most powerful Daemon Princes in existence. Jealous of those who have replaced him in the Dark Gods' esteem, he seeks to regain his power of old, to be once more raised above all other servants of Chaos as their unquestioned master. His pride is truly monstrous, and on more than one occasion it has proven to be his undoing. The greatest lords of the Ordo Malleus, those who know of this creature's existence, theorize that the Dark Gods have in truth abandoned their once-champion, discarding him like so many other proud Lords of Chaos.

Ever since the part Be'lakor took in the fall of Guilliman, he had been a thorn in the side of the Imperium. But there are also been recorded occurrences of him acting against the interest of Chaos, especially when the Ultramarines are concerned. He takes a great pleasure in slaying the Champions of the Chaos Gods among them, proving his superiority over the scions of the one who was chosen over him as the supreme leader of Chaos during the Heresy. It is most likely that he remembers his fate at the Arch-Traitor's hand, and still seeks to avenge himself upon all of Guilliman's progeny, proving once again that one of the Imperium's greatest assets in the war against Chaos is the division in its ranks.

Be'lakor revealed to Guilliman that he had been the one behind the eruption of civil war on Macragge which had led to the death of the Primarch's foster family, decades ago, and taunted Guilliman over his powerlessness to prevent it. He even claimed that the soul of both Konnor and Euten were in his grasp, and that he drew both power and amusement from their eternal torment. Enraged beyond measure, the Avenging Son vowed to destroy the creature, only for the Master of Shadows to withdraw his forces back through the Cadian Gate and into the Eye of Terror, daring Guilliman to follow.

It is unknown whether Guilliman's next decision was entirely motivated by rage and sorrow. It is possible that, having witnessed the power of the daemon armada, he believed it to be too dangerous to be allowed to escape and return to attack the Imperium at a later date. The previous disaster his Legion had faced when it had faced the Osirian Psybrids, and the desolation they had wrecked before being exterminated, might have played a part in his reasoning as well. But whatever his motives, Roboute ordered the 12th Expeditionary Fleet to pursue the daemonic ships into the great Warp Storm. Many of his sub-commanders – and near all the Navigators of the fleet – advised against such a course of action, but the Avenging Son ignored them all.

We have little details on what happened to the 12th Expeditionary Fleet in the Eye. The nameless remembrancer's account turns into metaphors and symbolic depictions at this point, probably reflecting the author's own limited perception of the madness surrounding him. From what can be understood without risks to one's sanity and soul, Guilliman led his forces across the width and breadth of the Eye, hunting down Be'lakor while the Master of Shadows remained always just one step beyond his reach. The will of the Primarch opened the tumultuous seas of the Eye before the fleet, or maybe the Dark Gods allowed him relatively safe passage. Nonetheless, countless crew members were lost to insanity or the depredations of Neverborn slipping past the ships' ever-raised Geller Fields.

During that fearsome journey, the Ultramarines fought against Be'lakor's forces on several daemon worlds, when the Librarians sensed the presence of the Firstborn on the world. Each time, however, their quarry would escape, and each time, less warriors would return intact from the ordeal – or return at all. Mutations began to appear on those Ultramarines who fought under the baleful skies of daemon worlds, and all suffered under the psychic weight of Slaanesh's echoing birth-cry. In each such battle, Guilliman led his men from the front, eager to confront the Master of Shadows. But as his goal eluded him time and again, the horror of his surroundings slowly ate at his resolve and mind. Entire subjective years passed between each battle, and still Guilliman fought, his sons following him loyally despite their increasing losses, convinced that the evil they were pursuing could not be allowed to exist.

Walking the graveyard of the Eldar Empire, Roboute came to learn the secret of the Fall : how, through their indulgence and excess, the children of Isha had created a god that consumed their souls when it awoke. He saw indisputable proof of the existence of the Dark Gods and their legions of daemons, contrary to what the Imperial Truth claimed. He was also shown visions of the Imperium's future, where the ideals of the Great Crusade had been abandoned in favor of totalitarian oppression and the rule of unworthy souls in the name of a distant Emperor – a future where all traces of Guilliman's own legacy had been erased.

So it was that, as he pursued the tormentor of his foster parents' soul in the underworld, Roboute Guilliman began to believe that the Emperor had lied to His sons. That the glorious future He had promised for Mankind, one free of the shackles of faith and tyranny alike, was a lie. Slipping further and further into madness, Guilliman came to believe that as things stood, there were only two possible paths for Mankind. Either it would be destroyed in the manner of the Eldar, when uncontrolled psychic power gave birth to a new primordial entity, or all humans would be caged, their souls kept from shining too brightly through dictatorship in order to prevent them from creating this same entity. The Primarch thought that this latter path was the one his father intended for Mankind, and though it repulsed him, Guilliman admitted to himself that it was better than the alternative. It disgusted him that Mankind would have to return to primitive superstition so that it might survive, abandoning the vision of reason that governed the current age for the protection of ignorance.

But then, just as his faith in his father was vacillating, the Dark Gods reached out to Guilliman, and offered him a third option. As he was fighting yet again Be'lakor's armies, they presented him with another path. Mankind could master the powers of the Warp, they whispered. Humans could follow the path that the Eldar had been too cowardly to thread, and become the junction between the Empyrean and the Materium, shedding their mortal flesh to ascend into immortality and godly power. All Guilliman had to do was replaced his father on the Golden Throne and direct Mankind down that path.

Guilliman's decision to turn against his father wasn't immediate. In the long hours of the battle, his mind wandered, and the Primarch was torn between was seemed to him like two equally ignoble paths. In the end, however, he broke, and swore that he would save Mankind from the Emperor's flawed designs. At the moment when he gave up, his latent psychic abilities, dormant ever since his duel against the Psybrid-King, fully awoke. Using them, he tore a path through the daemonic hordes and finally confronted Be'lakor.

'At last,' said the Daemon Prince as the Primarch approached him, his aura aflame with new-found power. 'Finally, you have accepted the inevitable.'

'Yes,' admitted Guilliman. 'Now I know what I have to do.'

'And what do you have to do now, Avenging Son ?' asked the Master of Shadows, a smug smile on his face.

It was the Primarch's turn to smile – an expression unlike anything he had ever shown before, combining hopelessness, bitterness, and a cruel joy. The eyes of Guilliman were filled with a feverous light and his face was pale, as if he was under the assault of some disease.

'I have to kill you, Be'lakor.'

'What ?!'

With Be'lakor's defeat, the title of Dark Master of Chaos which had belonged to the daemon for untold aeons passed on to Guilliman. Immediately, the Neverborn legions that had been fighting the Ultramarines either fell to their knees in obedience or disappeared back into the aether. Then, four Greater Daemons manifested upon the deserted world, one representing each of the Dark Gods. Each of the daemonic lords offering a gift to Guilliman before departing – a combination of unholy knowledge and dark power – while the rest of the Ultramarines watched in awed silence. When he had received the last gift, Roboute addressed his sons. He told them of what he had learned, and asked if they would follow him as he took the actions necessary to ensure Mankind's survival. All of the Legionaries present, who had seen many of the things their Primarch had seen with their own eyes, agreed, and knelt once more before Roboute Guilliman, the next Emperor and saviour of Mankind.

With his new powers, Guilliman led the remnants of his fleet out of the Eye of Terror and back through the Cadian Gate. Of the fifty thousand Astartes that had followed him into the Eye of Terror, less than ten thousand remained, and all of them bore the marks of their sojourn in the Grave-Birth. On their path, a thousand of them found themselves further altered by the change of allegiance of their Primarch : they became Secondborn, sharing their flesh and soul with a creature of the Empyrean. They gained great power through their transformation, but were also afflicted with dark hungers, now preying upon the humans they had sworn to protect. The Librarians who had accompanied Guilliman into the Eye had also been changed by their ordeal : endless exposition to the whispers of Chaos had driven them insane, corrupting them with the promise of power and knowledge that could be used against the armies of the Firstborn Son. They had become Sorcerers of Chaos Undivided, their souls forfeited to the very powers they sought to master.

Upon emerging from the Eye, Guilliman was greeted by emissaries of the First Legion. He was shocked to learn that even though decades had passed from his point of view, it had only been a few days for the rest of the galaxy. Even more surprising to him was the fact that the Dark Angels knew of what had transpired within the Eye of Terror, and that their master Lion El'Jonson had learned the same truths as Guilliman long ago, and made a similar choice. The emissaries offered the allegiance of the First Legion to Guilliman's cause, and said that their master was eager to meet with his brother once more, so that he might explain what plans he had already set into motion, and discuss what else they might accomplish together.

'The roars of the Master of Shadows shook the very aether with their fury. Despite his defeat, the Firstborn of Chaos was mighty still, and he was calling out to his forebears, demanding that they return to him what he believed was rightfully his. He screamed and shouted, claiming that instead of kneeling to him as was planned, the Chosen Harbinger had taken from him the mantle of Dark Master of Chaos, which the princeling had held since he had been first created.

For a time, the observer was content to just watch, delighting in the anger of the foolish princeling. But the watcher had a mission of its own, bequeathed upon it by the Great Mutator Himself. Be'lakor yet had a place in the Great Game, and couldn't be allowed to remain here for the rest of eternity, demanding an audience that would never be granted – as amusing as that would be.

And so, the two-headed Lord of Change revealed its presence to the princeling, and told him that all had occurred according to the Four Kings' desires. These desires had not been the same as the princeling's, true, but in his ignorance, he had well fulfilled his role nonetheless.

Greater still than before was the rage of the princeling at the revelation that his sires had used him yet again in their games, and he vowed that he would prove himself more deserving of the mantle that had been taken from him. He would show the Four Kings that he and he alone was their rightful champion and heir, and all usurpers would be cast down before his throne.'

From the Codex Chaotica, First Chapter, One-hundred-and-eleventh Verse

The Heresy : First Among Traitors

'Throughout our history, thirteen has ever been regarded as an accursed number. In many of the old religions, there were twelve main gods and a thirteenth being regarded as evil. It evokes an unneeded addition to something already perfect, which can bring it down from within. For thousands of years of mysticism, it has been associated with treachery. Maybe we should have paid more attention to the wisdom of the ancients when we dismissed it all as superstition.'

Attributed to the Primarch Magnus

In the following years, the Primarch of the Ultramarines worked alongside his brother of the First Legion to prepare the ground for the Heresy. Though Guilliman was wholly turned to Chaos by the time he returned from the Eye of Terror, he knew that he couldn't turn openly against his father yet, even with the Dark Angels at his side. He was held in high regard among the Imperium's armies, but he held no formal authority greater than that of his brothers, and few would follow him in outright rebellion. He needed to gather allies, and to make sure that his own Legion would obey his orders when the time came. Those who had come with him to Cadia and into the Eye of Terror would obey his every command, but the bulk of the Ultramarines were dispersed across the galaxy, still ignorant of their Primarch's transformation. They had to be brought into the fold, and those who wouldn't accept the new truth of the Thirteenth Legion would need to be taken care of.

Guilliman returned to the Great Crusade, hiding his transformation with sorcery, while he scattered those of his sons who had been changed by the Eye to the confines of the galaxy, fighting wars far from the prying eyes of other Legions. Then, for several decades, he plotted and schemed. He sent agents to the rest of his Legion's Chapter, slowly introducing their commanders to the truths he had discovered in the Eye. Some were brought before the Primarch himself, who explained to them what he had seen and what he had to do. Most accepted to follow their liege lord, trusting in his wisdom even though the very notion of rebellion seemed unthinkable to them. It isn't difficult to guess what happened to those who refused to see things Guilliman's way.

All this time, the traitors were sheltered from the sight of the Thousand Sons, who screened the galaxy for threats from the Throneworld. A resurgence in Warp Storms had occluded much of the galaxy, making Warp travel longer and even more dangerous. Whole Expeditionary Fleets were lost to the Sea of Souls with all hands, though some of them later reappeared under the Arch-Traitor's banner – Guilliman must have spirited them away as he massed forces, or perhaps they were driven mad by their time in the Warp and came to embrace Chaos on their own.

In secret, Guilliman ordered his Apothecaries and gene-smiths to increase the numbers of his warriors even further. At that point in time, the Ultramarines were already one of the most numerous Legions, with only the Raven Guard being undoubtedly superior in numbers (if not in quality).

Some of the Legionaries created during this period of rapid expansion included new, forbidden sciences in their creation : the Evocatii. Kept far away from inquisitive eyes, some of the Evocatii appeared to be normal Legionaries, but were in fact cloned humans who had been artificially grown and aged. Others had their genetics mixed with those of alien species with powerful abilities, or even combined with the dark science of the Warp. These warriors were often little more than puppets, capable of following orders with discipline and efficiency, but utterly lacking in initiative, and appearing to the perceptions of Librarians as psychic blanks in the Sea of Souls. It is rumoured that a handful of Evocatii were created with the Pariah gene, in order to deploy them against loyalist Librarians – but no trustworthy record of such abominable creature exists.

It is believed that Guilliman secretly pushed his brothers to denounce Magnus as an heretical sorcerer, provoking the Emperor to order the Council of Nikaea. The Arch-Traitor didn't know what exactly his father's judgement would be, but was confident that he could use it to his advantage either way. If the Emperor allowed the Thousand Sons to continue their practices, it would drive the Wolf King in opposition to Him, and if He rebuked the sons of Magnus, they in turn might become vulnerable to Guilliman's persuasion. Given the important part that the Fifteenth Legion played in protecting Terra against the sorcery of the Dark Angels during the Heresy, it is clear that the Emperor's ultimate decision was the correct one, even if it did cost a lot.

The Spineam Coronam

More commonly called the Crown of Thorns in Lower Gothic, this organization is a foul legacy of the Arch-Traitor that had plagued the Imperium for ten thousand years. When Guilliman was planning his betrayal, he knew that not all of the Imperium would follow him, and he also knew – perhaps better than any other Primarch – that there was more to the strength of the Imperium than the might of its armies. Over the years, he infiltrated agents into the Administratum and other organizations of the Imperium. Trained directly under him in the arts of deceit and minor sorcery, they were to weaken the Imperium from within, helping to usher in the ultimate victory of the Traitor Legions. Through murder, misinformation, and sabotage, these "Thorns" caused untold damage during the Heresy.

However, their existence didn't end when their master fell. Every original member of the Spineam Coronam was fanatically devoted to the Arch-Traitor, and they continued their mission even after his death. Guilliman had planned that the Heresy might last several human generations, and ordered his agents to train apprentices – one per agent – that would in time replace their master. Over the millenia, these chains of master-apprentice have endured, though many have been discovered by the Inquisition and destroyed. Seven times already the whole organization has been believed extinct, only for another of its infamous lineages to be discovered decades – or even centuries – later.

Guilliman also had a hand in the downfall of other Legions. He sabotaged the White Scars' efforts in the Chondax System and turned the powers of the Warp against the Khan and his sons. He set Sanguinius on the path to Signus Prime, after having arranged for the Angel to find the system in the hands of his Neverborn allies. The true scope of Guilliman's part in his brothers' corruption may never be fully revealed, but when he believed half of the Legions would stand at his side, he activated the next phase of his plan. He called his corrupt brothers to him, and they prepared for the event that would spark the Heresy : the Isstvan Atrocity.

The Ultramarines sent thousands of their own to Isstvan III. Each of the warriors had been unknowingly condemned to death by his superiors, for it was believed that he wouldn't follow the orders of their Primarch when Guilliman ordered his men to turn against the Emperor. Marked for censure, ostensibly for defiance against orders or any other petty reason, the betrayed sons of Guilliman were told that Isstvan was to be their redemption. By obeying their deployment orders to the letter and prosecuting the campain against the rebels in the exact manner Guilliman and the other Primarchs had planned, they would prove that they had learned from their mistakes. Because of this, a far greater portion of Ultramarines was exposed when the first bombs fell, and very few of the loyalist Thirteenth survived the first seconds of the battle for Isstvan III. Those who did, however, found a leader worthy of legends in the person of Aeonid Thiel.

Aeonid Thiel, Lord of the Red Mark

The Space Marines who were marked to die on Isstvan III were all honorable warriors, whom their corrupt Primarchs knew wouldn't follow them into treachery. All Astartes of today honor the memory of the few whose names are known to us, yet few of these heroes are as famous as Aeonid Thiel. A sergeant of the Thirteenth Legion, he was known to challenge his superiors' decisions, more often than not making excellent points as to why their actions were erroneous. Despite his skill in battle and deep instinct for tactics, this attitude prevented his further rise in the ranks. When the Captains and Chapter Masters received the order of listing those of their men whom they thought weren't trustworthy (somehow failing to notice the obvious irony in such a command), it was with a certain satisfaction that Thiel's superior officer marked him down.

Like all Ultramarines deployed on Isstvan III, Thiel wore the 'Red-Mark' : his helmet was painted in red as a sign of his censure. By then, every Legion knew that those of the Thirteenth with a red helmet had somehow disgraced themselves, and the members of the Blood Angels, Imperial Fists and Iron Hands deployed on the planet questioned why all the forces of the Ultramarines – whose Primarch was ostensibly the one leading the whole operation – were composed solely of such warriors. But they didn't suspect the truth until the first bombs fell, and can hardly be blamed for it.

Like hundreds of others, Thiel survived the initial bombardment of Isstvan III, taking shelter in the city's catacombs while fire scoured its surface. When he and his brothers emerged, the full realization of their father's and brothers' betrayal hit them. While Captains fell to their knees in despair, Thiel managed to keep his wits, focusing all the might of the soul-searing hatred he now felt for his erstwhile comrades on the prosecution of his duty. The rest of the loyalist Ultramarines gathered around him, and they exacted a heavy toll of treacherous lives during the battles that followed on Isstvan III. Using unconventional tactics and daring stratagems, Thiel and his men achieved kill-ratios never seen before during the Great Crusade, and rarely equalled during the Heresy. Thiel himself slew several champions of the four Traitor Legions present at Isstvan III, including his own former commanding officer.

What truly sets Aeonid Thiel apart from the rest of his fellow Isstvanian heroes is that, unlike most of them, he actually survived the battle. During the final days of the loyalist resistance, the leaders of the faithful decided that one of them had to survive, to escape the world so that the fight would continue and the galaxy would remember that not all sons of the traitor Primarchs had followed their fathers into rebellion. Thiel argued vehemently against being chosen, wanting nothing more than to stay and fight alongside his comrades – no matter their Legion – but he was overruled. The other leaders believed him to be the most apt of them for the kind of war that awaited them, and the one with the best chance of actually escaping the planet. Conceding to their decision, Thiel took a handful of warriors with him – not just Ultramarines, but also Space Marines from the other three Legions – and seized a traitor gunship just as Guilliman ordered the final assault on the loyalist positions. In orbit, the twenty Legionaries captured a small traitor ship and, through the techno-expertise of the Iron Hands among them, they slipped away from the rest of the fleet and vanished into the Warp.

In the years that followed, reports reached both the Imperium and the rebel commanders of a group of Legionaries wearing armor of different livery attacking traitor assets. These warriors had only one thing in common : they all bore a red helmet. Elements from both loyal and traitor Legions rallied to Thiel's banner, and they became a force to be reckoned with in the Shadow Wars. Entire worlds were spared from annihilation when a strike force of the Red-Marked slew a particular leader or destroyed a supply line, forcing the traitors to redirect resources to deal with a threat that had vanished long before they arrived. Separating Thiel's actions from those of the Twentieth Legion during that time is all but impossible, but it is estimated that at least ten thousand Traitor Marines were slain as a result of the Red-Marked's deeds, with countless other military assets destroyed in the process.

As is the case with so many things that occurred during the Heresy, the ultimate fate of Aeonid Thiel remains unknown to us. It is rumoured that Thiel's armor, upon which he inscribed all the stratagems he ever used against the Traitor Legions, was reclaimed by the Alpha Legion upon his death, and is enshrined in whatever world it is that the mysterious sons of Alpharius call home. To this day they study the writings of the Lord of the Red Mark, sharpening their minds and preserving Thiel's legacy. Though the Imperium at large doesn't recognize Thiel's existence, many Chapters of the loyal Legions honor his and his warriors' memory by having their own champions paint their own helmets red – a sight that always seem to enrage the treacherous warriors of the Thirteenth.

After the purge of Isstvan III was completed, Guilliman and his cohorts prepared for the inevitable Imperial reaction. Initially, Roboute had planned for the Emperor to remain ignorant of his betrayal, so that he and the Legions loyal to him could attack Terra itself by surprise and win the war before it was even openly declared. But the escape of the Imperial Fists loyalist vessel Tribune forced him to reconsider his initial plan and to turn to one of his many contingencies. Though the Master of Mankind now knew of His wayward son's treachery, He had yet to realize the true scope of the betrayal, and Guilliman could turn the escape of Captain Pollux and his warriors to his advantage. It would require that he sacrifice the Five Hundred Worlds to the Ruinous Powers, but the Primarch was already so far gone that it is doubtful this caused him even a moment of doubt. He sent astropathic messages to the cults he had spread on each world of his kingdom, commanding them to begin the sacrifices that would pave the way for the Ruinstorm, when Marius Gage sacrificed himself and the warriors under his command to the powers beyond the Veil.

With the World Eaters and Word Bearers on their way to Ultramar, Guilliman still had to prepare the second part of his galactic trap. Contacting those of his brothers whose true allegiance hadn't yet been revealed, he orchestrated the events of Isstvan V, where the Night Lords, Death Guard and Alpha Legion were butchered on the ground of that cursed world.

On Isstvan V, the Ultramarines stood at the head of the traitors, and took the brunt of the loyalists' hatred. It was in this battle that, for the first time, Guilliman unleashed the thousand warriors who had been possessed by daemons on their way out of the Eye of Terror : the Daemonium Venatores, the Demonic Hunters. These Secondborn Astartes tore their way through the loyal Legions, their appearance causing shock and horror among those who had been their cousins.

The Daemonium Venatores

First of the twice-cursed Possessed Marines, the Venatores are those few Ultramarines who became Secondborn during the Thirteenth Legion's journey into the Eye of Terror and survived to this day. Their exact number is impossible to know : there were at best a thousand at the onset of the Heresy, and they took terrible casualties on the black sands of Isstvan V, with no way to replenish their ranks. Nonetheless, they remain a potent threat, for each of them is far more powerful than the other Secondborn that were created after them.

After Guilliman had taken the power of Dark Master of Chaos from Be'lakor, only the more powerful daemons were capable of piercing the veil he cast around his fleet and possess one of the Ultramarines aboard. And only the best warriors had survived the trials of the long war against the Master of Shadows. Thanks to this, these unions of Astartes and Neverborn created beings of great power and skill. Up till the battle of Isstvan V, the Venatores were capable of assuming their mortal form, hiding their monstrosity beneath plates of !br0ken! But when the first drops of loyal blood hit the sand, they lost control of their powers and transformed into the aspects they would assume until their dying days.

Each Daemonium Venatore is different from the other, but they are all taller than even a Terminator Marine, with a variety of natural weapons and abilities. Among Ultramarines, they do not lead, for their nature prevents them from commanding efficiently – they are often consumed by their hungers, or contemplate matters beyond mortal senses. They are instead employed as champions, paid in blood and souls. On the battlefield, they target the enemy's best warriors in order to devour their souls and add to their own power and standing in the eyes of the Dark Gods.

After the remnants of the three loyal Legions escaped the Isstvan system, Guilliman, convinced that they were broken forever, gathered his brothers. He asked that they advance on Terra together, destroying all loyalist worlds in their path, until they reached the Throneworld and he could challenge their father. But he quickly found out that his brothers had other plans. Lion El'Jonson wanted to go and bring the Wolf King to their cause; Jaghatai Khan was nowhere to be seen; Rogal Dorn and his sons wanted to get their revenge on all worlds fortified by the Iron Warriors; Sanguinius was lost to the madness Guilliman had plotted for him and unable to direct his sons; and Corax and Vulkan each had their own agenda. Only Ferrus Manus was both willing and able to keep his warriors at the Ultramarines' side on their march to Terra.

But despite this scattering of the Traitor Legions, the Imperium was still on the brink of destruction. Civil war raged on thousands of worlds as all of the Great Crusade's lords chose one side or another. The agents Guilliman had hidden among the Imperium's infrastructure also spread discord and confusion. At first, nothing seemed to be able to stop the advance of Chaos toward Holy Terra, and the worlds that fell before the combined might of the Thirteenth and Tenth Legions became dark wastelands, inhabited only by twisted mutants and cruel daemons, who fed upon the tormented spirits of the dead. With each planet that fell, the power of the Ultramarines grew, for more and more of their number were consecrated as Champions of the Dark Gods and received their blessings in return for the sacrifices they offered in the arena of war.

Of the loyal Legions, two were trapped within the Ruinstorm and three had greatly suffered at Isstvan V. The Thousand Sons were still reeling from the destruction of their homeworld and the Iron Warriors had fought in the Olympian War and were embroiled in the conflict on Mars' surface. The Emperor's Children were missing – though it seems even Guilliman was unaware of the Dark Eldars' actions, since he looked for the Third Legion during the entirety of the Heresy. Only the Sons of Horus stood steadfast, and one Legion could not hope to match the combined might of the Dark Gods and the renegade Primarchs … but Guilliman's estimations were wrong.

The Legions he had thought broken on Isstvan V soon showed that they were anything but. While the Death Guard returned straight to Terra to add their remaining forces to the Throneworld's defence, the Alpha Legion and the Night Lords scattered across the stars, each group acting to slow the rebels' advance. What Guilliman had believed would be a matter of months instead slowly stretched into years. Worlds that should have surrendered or even joined the rebellion instead fought to the bitter end, their people roused and equipped by Alpha Legion operatives, while the rebels' commanders were targeted by Night Lords strike teams and agents of the Officio Assassinorum.

It was inconceivable to Guilliman that such resistance to his forces could be the result of uncoordinated groups. The Arch-Traitor was convinced that there was someone, probably one of his brothers, commanding all the resistance cells, and that if he could just locate and kill that individual, progress toward Terra would resume at the anticipated speed. After several years, his agents reported to him that they had located the Primarch Alpharius, who had escaped the carnage of Isstvan V alongside the elite of his Legion. Alpharius had taken refuge on the world of Eskrador, alongside thousands of the Twentieth Legion's survivors.

Without wasting time, Guilliman entrusted the march to Terra to his brother Manus, and, with the elite of his Legion, he went to hunt down his brother. The details of what happened on Eskrador are unknown : while Guilliman was certain to have confronted and slain his brother, someone claiming to be Alpharius appeared at the Imperial Palace soon after the end of the Heresy. Furthermore, it wasn't the first time someone had thought they had killed the Hydra : already on Isstvan V, the elusive Twentieth Primarch had been believed slain. But whatever the truth, the command nexus on Eskrador was destroyed, and word that Alpharius had fallen spread across the galaxy.

But unlike what Guilliman had expected, the loss of Alpharius didn't affect the resistance to his advance at all. If anything, the warriors of the Alpha Legion redoubled their efforts, their desire for revenge stoked by the apparent murder of their Primarch. What the Arch-Traitor had failed to see was that, unlike his own Legion, the sons of the Hydra had been trained in individual thinking more than any other Astartes in the galaxy. While perfectly able to work together, each of them was an army in himself, a force capable of acting independently if the circumstances so required. Alpharius had directed some of the Alpha Legion cells, but not all, and even they had quickly adapted to the disappearance of their Primarch. It was only through a succession of gruelling campains that, at long last, Guilliman's forces reached the Sol system. The Arch-Traitor called his wandering brothers to him, and they answered, sensing that the final battle was at hand. Forces from all Traitor Legions converged with the Ultramarines and Iron Hands' own fleets in order to confront the defenders of the Throneworld.

The Siege of Terra

From his spies, both humans and daemonic, Guilliman knew that Perturabo had built up the defenses not just of Terra, but of the entire Sol system. Dozens of asteroids had been hollowed out and turned into space forts, and the moon of Titan had become the fortress-monastery of those who might very well be Guilliman's greatest threat : the Grey Knights. The Arch-Traitor knew little of these warriors, only that each of them had been hand-picked by Malcador the Sigillite, and blessed with power from the Emperor Himself. Guilliman was reluctant to engage them, and designed a plan that would deal with the system's defences while also neutralizing the knight-errants.

Guilliman selected forces from all nine Legions under his command to be part of the first wave of attacks, including a full Chapter of his own Ultramarines and supported by hundreds of traitorous Imperial Regiments. These troops were given false information about the system's defences, however, and they were slaughtered by the Iron Warriors' guns, while the rest of the Chaos armada held back from joining the fray. All while his men died, Guilliman's Sorcerers harnessed the energies of the massacre to cast a grand ritual that sundered the veil between the Warp and reality, and summoned the very daemonic fleet that the Ultramarines had fought in the Eye of Terror decades before. These daemonships destroyed the system's outer defences, and it is written that Be'lakor himself descended upon Titan at the head of a new daemonic legion, hoping to restore his standing in the eyes of the Dark Gods by destroying the Grey Knights and preventing all the damage they would inflict to Chaos in the future. He failed, but the battle that the Grey Knights waged against him occupied them for the entirety of the Siege, and prevented them from coming to the aid of the Emperor in His hour of greatest need.

With all obstacles removed, the rest of the traitor forces entered the system, and the assault on Terra herself began. Tens of thousands of Legionaries landed on Terra, accompanied by millions of traitor soldiers and scores of Titans. Guilliman had devised a complex plan to bring down the Palace's walls, but he lost control of his allies the moment they landed on the Throneworld's sacred soil. The Blood Angels attacked the civilian population of Terra, while groups of Space Wolves and White Scars ignored their orders to attack on their own. Meanwhile, Horus and Perturabo directed the loyalist defenders of the Palace with their combined genius, while Mortarion fought on the frontlines and Magnus and his sons shielded the Palace from the traitors' sorcery.

Days passed without any progress being made, and Guilliman grew impatient. The Neverborn were wispering to him of Lorgar and Angron's escape from the Ruinstorm, and their vengeful return to Terra. When they arrived, he would be forced to recall some of the Legionaries on the planet to face the Twelfth and Seventeenth Legions in the space battle that would follow, which would create an opportunity he knew Horus wouldn't miss. Even when the Warmaster fell at Sanguinius' fangs, Perturabo managed to keep control of the combined Legions, preventing the warriors of Sixteenth from losing themselves to their thirst for revenge.

Then the two Legions Guilliman had lost trace of, the Night Lords and the Emperor's Children, suddenly joined the battle. With the sons of Nostramo on the surface of Terra, the traitors' assault on the Palace faltered, while the Emperor's Children wrecked havoc among the renegades' fleet. Simultaneously, the Sons of Horus counter-attacked and slew the Daemon Primarch Sanguinius, taking nearly all of the Ninth Legion out of the fight.

Seeing his chance to seize the Golden Throne slip away, Guilliman decided to risk everything on one last gamble. Through his Neverborn allies, the Arch-Traitor had learned of the Webway entrance within the Imperial Palace, the heart of the God-Emperor's great work. If he could reach it and break the seals upon it, then he could unleash a daemonic army that would consume all human life on Terra, but also give him the strength to face all the Legions arrayed against him. Telling his allies that they were to perform a strike toward the Emperor, hoping to kill Him and break the loyalists' morale, he led one final assault on the Palace's gates. While a distraction force drew Mortarion away, Guilliman took with him Rogal Dorn, Lion El'Jonson, and the elite of their respective Legions, and tore a way into the Emperor's Sanctum.

On his way, the Cavea Ferrum separated the three forces, with Guilliman and his Ultramarines alone reaching the Golden Throne. There, the Arch-Traitor confronted his father at last, while around them, Custodes fought against the elite of the Thirteenth Legion.

He expected to see hate. He should have seen hate. After all, he had betrayed everything the god stood for. He had laid ruin to the god's dream, and damned Mankind to an existence of fear and eternal war. And yet, he saw no hate in his father's eyes …

He only saw sorrow and pity, and it drew him mad.

The two of them clashed together, and history was written in the blood of a god and His fallen angel. Guilliman's power was fueled by all four Chaos Gods, who saw this as their only chance at defeating the one being they feared in the entire galaxy, for He alone had the power to destroy them, in some potential future that might now never be. Weakened by the years of repelling the Dark Gods' attacks from the other side of the Webway Gate, the Emperor was unable to match His son's madness, and He was mortally wounded by the Gauntlets of Ultramar, ancient weapons which had been reforged anew in light of Guilliman's change of allegiances, and now burned with the unholy flames of Chaos.

But just as His body was dying, the Emperor was saved by the arrival of Fulgrim, who teleported right in the midst of the battle. Wielding the sword that had been forged for him by his brother Ferrus in an earlier, happier age, the Phoenician struck at his traitorous brother with all the skill and hatred that animated his scarred form, and with a wordless cry, the tongueless Primarch brought low Guilliman's guard. Using this opening, the Emperor rose with His last remaining strength, and unleashed a stream of golden psychic energy on Guilliman, snuffing out the light of his dark soul forevermore.

When they saw their father falling, the Ultramarines cried out in despair. Many of them gave their lives to reclaim his body, and they fled through the Cavea Ferrum, many more losing their way and wandering through its corridors until they were found and put down – in some cases years after the end of the Siege. They withdrew to their ships in orbit and fled the Sol system, abandoning their allies to the Imperial retribution.

Post-Heresy : Cursed Among Fallen

'And thus, banished to the Hell their father created,

The sons of Guilliman, the treacherous Thirteenth, were cast down from the Emperor's Light,

To prey upon one another forevermore, under the laughter of cruel gods.'

Excerpt from The Canticle of the Dead

Despite their considerable remaining strength, the Ultramarines have, in many ways, fallen lower than any other Legion after their defeat at Terra. While individuals among them continue to enjoy the favor of the Ruinous Powers, the failure of the Thirteenth has caused them as a Legion to be abandoned by the very Gods that once elevated them above the other traitors, cursed to suffer even more than the rest of the Treacherous Nine.

The first sign of that displeasure occurred soon after the Siege of Terra ended in the Ultramarines' shameful flight. As the Iron Cage around the Ruinstorm was being completed, the Ultramarines commanders gathered on Macragge to discuss a common attack in order to prevent Perturabo's jail from being completed. The warlords met in the mausoleum of Guilliman within the Fortress of Hera, so that the Primarch's spirit might guide their decisions – and to ensure peace was preserved among the participants. However, just as the talks were about to begin, a fleet of Ultramarines vessels and daemonships appeared in-system, attacking the ships each Chapter Master had brought with him. At the head of the armada was the reborn Marius Gage, elevated to daemonhood and coming to destroy the corpse of the father who had left him to die. The Ultramarines who fought under him were similarly disappointed with their Primarch, and sought to free themselves and their brothers from the shackles of the past.

The assault failed to ever reach Macragge's surface, but several of the Ultramarines warlords were slain, and in the utter confusion that followed, it became clear that no one could unite the Thirteenth now that its Primarch was lost to his sons. Some warlords chose to run, while others stood and fought, all on their own, refusing to take orders from others. Gage and his minions were pushed back and forced to flee, but at a far heavier cost than what was necessary. Blaming each other for their respective losses, the remaining lords separated on bitter terms, all hope of the Ultramarines coming together again forever shattered.

Marius Gage, the Sacrificed Son

The name of Marius Gage is cursed both by loyalists for his part in the Shadow Crusade and Ultramarines for his actions since. Once, he was master of the Thirteenth Legion's lauded First Chapter, a commander of ten thousand Astartes – the best of the whole Legion. Before Guilliman was reunited with his sons, it was Marius Gage that led the entire Thirteenth, with all the skill that could be asked of a Legion Master. His loyalty to his Primarch was absolute, but when he was ordered to stay behind on Calth and die so that Roboute's plans could be accomplished, something broke within the Sacrificed Son. The Warp took advantage of that weakness, and poured into his soul, reshaping him into a rabid madman by the time Angron and Lorgar reached Calth. It was thought that Marius gave his life to unleash the Ruinstorm, and it appears that even he believed that the ritual that summoned the Daemon Prince Samus would destroy him … but the Dark Gods had other plans.

For his part in unleashing the Ruinstorm, Marius Gage was elevated to the rank of Daemon Prince. His devotion to Guilliman turned into hatred, and when he finally emerged from the Warp after the end of the Heresy, he swore to destroy the heritage of his gene-sire. After his failed assault on Macragge ten thousand years ago, he retired to the world of Calth, which he rules from orbit in his daemonship, a Space Hulk named the Sorrowful Wail. Under him serve the Ultramarines who grow disillusioned with Guilliman and seek out a new master, as well as renegades from other Legions who have fled into the Ruinstorm. These renegades come from other Traitor Legions, but also from those whom Primarch remained loyal to the Emperor, in a blasphemous echo of the very unity Guilliman's betrayal murdered.

Gage still seeks to unite the Ultramarines under his command, believing that he is the worthy inheritor of Guilliman, as the only Legion Master left. To this end, he still thinks that he must destroy Guilliman's body, in order to crush any lingering hope among his brothers that their father will one day return – as well as to satiate his unholy thirst for vengeance.

A thousand years after the failed attempt of the Chapter Masters to reunite the Legion, word spread within the Ruinstorm that the Imperium was weakened. The War of the Beast had just ended, and the Imperium had greatly suffered against the Orks. Countless worlds had been lost, and total collapse after the Beheading had only been avoided thanks to the timely return of the Primarch Angron. The time was perfect for a Black Crusade of unprecedented proportions, one that would shatter the Iron Cage and allow the Ultramarines to roam the galaxy freely once again.

A powerful Daemon Prince, risen from the ranks of the Thirteenth Legion, launched this Black Crusade, uniting many Chapter Masters and their warbands under his supreme command. Known only as the Ascended One, this creature led thousands of Ultramarines and millions of mortal soldiers. They crushed the worlds of the Iron Cage, weakened by recent attacks from the Orks, and prepared to continue their advance onto the worlds of the Imperium. However, even as these planets' defenders prepared to fight to the last against enemies that far outmatched them, salvation came from the most unlikely of place.

In the Eye of Terror, the eight Traitor Legions had also sensed the weakening of the Imperium. An alliance had been formed, and another Black Crusade had begun, piercing through the Cadian Gate – once more reducing Cadia to burning slag. The newly inducted High Lords of Terra saw this resurgence of Chaos, and feared that the Imperium had only survived the coming of the Beast to fall at the hands of the Archenemy. However, the Crusade force from the Eye converged to the galactic east, straight to the Ruinstorm. Medused, the Imperium watched as the two Black Crusades destroyed each other.

The Traitor Legions of the Eye remembered well how the Ultramarines had failed them during the Siege of Terra, when they had fled the battlefield as soon as their Primarch had died. They also remembered how Guilliman had sent so many of their brothers to die in order to weaken the defenses of the Sol system and thin the veil between realms, all for nothing in the end. To these treacherous souls, nothing had more importance than revenge, even the chance to destroy the Imperium in its hour of weakness.

An entire sector of space served as the battlefield between the two Chaos armadas, with hundreds of Imperial worlds burning in the crossfire. The Daemon Primarch Corax, leaving his daemonworld for the first time since the Heresy, fought against the Ascended One in single battle, and the two daemon princes destroyed each other's material form, banishing their spirits back to the Eye and the Ruinstorm. In the end, the Imperial armies came upon the remnants of the two hordes, and forced them back into their respective Iron Cages. The fortress-worlds that had been destroyed were rebuilt, and the whole event came to be known as the Unborn Crusade.

The last of the setbacks endured by the Ultramarines came from a source none could have predicted – perhaps not even the Dark Gods themselves. In the eighth century of the forty-first millennium, several worlds of the Iron Cage were lost, not to the Ultramarines or their daemonic allies, but to an outside force : the Hive-Fleet Behemoth. While the Imperium has faced other breeds of Tyranids in the past, this particular hive was apparently drawn to something within the Ruinstorm, for as soon as it had devoured the worlds of the Iron Cage in its path, it entered the Warp Storm, never emerging again. From what we know, the bioships were scattered by the Warp currents, and the Hivemind was brutally destroyed by the storm, reducing most of the Tyranids to mindless beasts. Still, their numbers were such that when they reached daemon worlds, the masters of the cursed planets had to use all their strength to defeat them. Many Ultramarines were lost to the Tyranids' fangs and claws, with even the homeworld of Macragge coming under attack by a force of xenos led by the infamous Swarmlord, who mutilated the Chaos Lord Marneus Calgar, ruler of Macragge, before it was defeated by the intervention of one of the four Tetrarchs.

It is highly unlikely that this most recent incident the Thirteenth Legion has met was the result of the Dark Gods' displeasure. The Tyranids are protected from their reach by the Hivemind, and its objectives – the consumption of all life within the galaxy – are at odds with the very continued existence of Chaos. Still, the question remains : what could possibly have driven Behemoth to enter the Ruinstorm ?

The Tetrarchs

Before the Heresy, Tetrarch was the highest rank an Ultramarine could achieve, whose authority was second only to that of Guilliman himself. There were four Tetrarchs, each of them ruler of one of Ultramar's most prosperous worlds, tasked with its protection and management in order to supply the many resources required by the Great Crusade – weapons, ammunition, heavy armor, soldiers, and so on. When the Arch-Traitor prepared his betrayal, he recalled the Tetrarchs to his side, sparing them from the sacrifice that would create the Ruinstorm and trap the Twelfth and Seventeenth Legions during most of the Heresy.

Though the worlds they had ruled were no longer in any mortal's hands, the Tetrarchs conserved their positions of power in the Thirteenth Legion. The four of them fought at their Primarch's side on Isstvan V, and served him well during the rest of the Heresy. They were emissaries to the other forces fighting under the Arch-Traitor's banner, and it was their efforts who kept the fragile alliance of the Dark Gods' followers intact until the time of the Siege.

In the course of that service, each of the four Tetrarch shed his humanity and mortal flesh to become a Daemon Prince, an immortal scion of the Ruinous Powers, bestowed power beyond the ken of mortal men. Yet despite their transformation, they remained subservient to the will of Guilliman, and continued to serve him until the very end. During the Siege of Terra, they fought at the head of their own Chapters, covering the advance of their Primarch into the Palace. Accounts from the Legionaries who were engaged with them at the moment of Guilliman's fall tell that they were banished into the Warp at the exact moment the Emperor's sword slew His traitorous son.

A century later, the Tetrarchs reappeared in the Ruinstorm. No longer leading others of their kind, but still respected and feared among the Thirteenth Legion, they now wander through the Five Hundred Worlds and beyond, seemingly able to move through the Iron Cage at will – to the great frustration of the Iron Warriors and the Inquisition alike. In the last ten thousand years, there have been hundreds of sightings of these Neverborn princelings. They work with heretics from all horizons, from lowly cultists in over-populated hives to Warmasters leading Black Crusades across several sectors. For millenia, the Ordo Malleus and the Thousand Sons have tried to establish a pattern in their actions, but so far, none have emerged. It is whispered among the Ultramarines that the Tetrarchs still serve Guilliman, somehow still hearing the will of the dead Primarch – but that is preposterous. The Emperor Himself destroyed the soul of the Arch-Traitor.

The true names of the Tetrarchs have long been lost, erased from Imperial archives in what many believe to have been a deliberate plot of the creatures to destroy all traces of their pre-daemonhood identity. It is well known that the true name of a daemon is a powerful weapon against it, and in the case of Daemon Princes, the name the creature had when it was still mortal is that name. Without a name, the four Tetrarchs are called by a series of titles, either self-bestowed or granted by their enemies. However, it is all but impossible to differentiate the four and know which one is responsible for which atrocity. The fact that they all seem to behave in the same way makes it even more difficult, and it has led many Inquisitors to believe that their connection goes beyond the mere rank they once shared. In the mind of the Iron Warriors, who most often face them in battle, the Tetrarchs are considered to be a single entity which just happens to have the ability of being in four different places at the same time.

Organization

Uriel Ventris, the Drinker of Sorrow

In recent years, the name of Uriel Ventris has become one of the most often used curses among the wardens of the Iron Cage surrounding the Ruinstorm. Born on the thrice-cursed daemon world of Calth, Uriel grew in the underground caves of the blighted planet until he was noticed by the Ultramarines warband who owned his entire clan. After his transformation into a Legionary, he displayed great wit and martial skill, quickly rising in prestige and influence. He is known to have slipped through the Iron Cage many times, leaving a trail of destruction across the galaxy each time. He is ruthlessly practical, and, contrary to most Ultramarines, do not regard the Dark Gods as his absolute masters, instead placing his own desires and ambitions over theirs. Lacking even the perverse sense of honor displayed by many Chaos Marines, all that matters to him is victory through any means. He doesn't even worship the Dark Gods, but instead sees them as questionable allies and the power they can grant in return for offerings as nothing more than a useful tool. This has made him a heretic in the eyes of many of his more orthodox brethren, but the results he has achieved are such that even then, there are those willing to follow him into battle.

It is on the world of Pavonis that Ventris earned his title. Making an alliance with Dark Eldar forces, he crushed the PDF and conquered the world. The atrocities the xenos visited upon the population were only equalled by those committed by Uriel himself, and the foul creatures named the son of Guilliman "the Drinker of Sorrows" as a sign of respect for his cruelty. After his allies from Commoragh had departed, their hulls filled with fresh slaves for the flesh-markets of the Dark City, Uriel journeyed to an ancient crypt that had been recently discovered by archaeological teams. There, he found one of the C'tan god-shards, and released it from its confinement in return for necrontyr technology. When the Imperial rescue mission arrived to Pavonis, not a single lifeform remained on the planet – the C'tan Shard had annihilated the entire biosphere. In return for liberating it, Uriel gained access to ancient necrontyr technology, which he used to gain the allegiance of several Dark Mechanicum hereteks.

He later had dealings with Thrar Hraldir, and together they attacked one of the Deathwatch's space forts and ransacked it, plundering its treasures and adding the knowledge accumulated by the Ordo Xenos to Hraldir's own fell wisdom. The markings left by the two heretics on the fort's wall allude to the coming of some yet greater atrocity, and the Holy Ordos are actively working on uncovering their sinister designs, while all Legion forces across the galaxy know to look for both of them and execute them on sight.

Since the days of the Heresy, all Traitor Legions have suffered from infighting. The poison of Chaos always turns brother against brother, and the death of loyalty is the one common trait among all of the Accursed Nine. Some of them have lost their Primarchs to death's embrace, while others have ascended into the Great Game of Chaos and become distant from their sons. But no Traitor Legion has been broken by the loss of its gene-sire like the Ultramarines have.

After the battle of Isstvan III purged those Ultramarines who had the most inclination to think for themselves, Guilliman's authority over his sons went from unquestioned to absolute. His word was considered not just law, but gospel by the warriors of the Thirteenth. Over the course of the March to Terra, the Arch-Traitor took on more and more direct control of the Legion's operations, to the point that his death crippled the Ultramarines far beyond the blow it inflicted on their morale. When the Ultramarines arrived to the Ruinstorm, none of them had the ability to hold the Legion together, and it came apart in hundreds of warbands. Some Chapter Masters were capable of keeping their own warriors under their control, while others either failed or were murdered by warriors they had often led for decades.

Unlike most other Traitor Legions, the Ultramarines have kept to the hierarchy they had before the Siege of Terra, though in truth, the difference is limited to the titles and ranks they cling to. Warlords are called Chapter Masters, and their subcommanders are called Captains, but they are far more similar to other Chaos warbands as they are to the organization of a true Legion. The size of the Chapters vary greatly, depending on the fortune of its members. Before the Heresy, standard size for an Ultramarine Chapter was ten thousand Legionaries, but almost none of the current Chapter Masters can boast to have such a force under their control. Some warlords of the Thirteenth Legion command thousands of warriors and rule over a dozen worlds or more, while others have less than a single Company's worth of Chaos Marines and travel the Ruinstorm aboard their accursed starships, selling their services to the highest bidder or going on quests of their own.

All Traitor Legions are divided to various degrees, and the Imperium rightfully dreads the unification of any of them under a new leader. But while the Ultramarines are a potent threat to all Mankind, the possibility of them uniting again under a leader different from their beloved Primarch is considered most unlikely by the Inquisition's analysts. The sons of Guilliman still worship the memory of their father, even those who became Legionaries thousands of years after his fall. They pray for his return, and in the meantime keep fighting each other for the resources of their infernal exile, each warlord refusing to submit to any of his brothers. During the Heresy, all Chapter Masters were equal under Guilliman, though some were higher in his favor. None of these favoured champions, however, held enough sway to convince the other Chapter Masters to follow him – not after the infamous Battle of Macragge and the Unborn Crusade.

Oberdeii, the Oracle of the Pharos

When the Ruinstorm was unleashed, it swallowed the whole Five Hundred Worlds and the encompassing region of the galaxy. All worlds, inhabited or not, became the playthings of the Neverborn and their dark masters … Safe for Sotha. Discovered in the early stages of the Great Crusade, Sotha was a peaceable world whose only particularity was the presence on its soil of the xenos apparatus known as the Pharos. Built by an alien species more ancient than even the Eldar, the Pharos was an instrument of galactic travel based on entirely different principles than those of our own Warp-drive technology. Through an empathic field, it allowed instant communication across galactic distances, and even point-to-point teleportation. Those who lived for too long near it started to have strange dreams, visions of possible futures. When the planet was discovered, a team of magos was sent to investigate, with an company of Iron Warriors to serve as escort and assist their work. Isolated from the galaxy, engrossed in their research of the Pharos' wonders, they were still on the planet when the stars above them turned blood-red.

However, Sotha did not become another daemon world. The Ruinstorm's influence was kept at bay, and the people of Sotha were protected from the madness of the Warp. In response to the Warp Storm, a so far unknown propriety of the Pharos had activated, shielding the planet. Through the use of the device, the loyalists trapped on the planet discovered what had befallen the galaxy at large, and vowed that they would prevent the Pharos from falling into the hands of Guilliman and his treacherous ilk. The sons of Perturabo fortified the planet, with the help of the magos and the farmers who had formed the bulk of Sotha's colonists thus far.

For several decades, the defenders of Sotha prospered under the rule of the Iron Warriors. When the Ultramarines returned to the Ruinstorm in the Heresy's aftermath, however, many of them sought to claim the Pharos and dedicate it and the untouched planet to the Ruinous Powers. For years the Iron Warriors and their allies fought, cut off from any hope of reinforcement. Then one of the Tetrarch joined the forces gathered at the edge of the Pharos' protective field, and reached out to a young native of Sotha called Oberdeii.

Driven mad by the combined effects of the Pharos and the whispers of the Daemon Prince, Oberdeii ventured deep into the heart of the mountain housing the xenos device, past the mapped regions of the labyrinth of caverns and passages. What happened in those depths is unknown, but it caused the collapse of the barrier. With the help of their daemonic allies, the Ultramarines ransacked the planet, enslaving its people and inflicting hideous tortures upon the Iron Warriors. The Tetrarch led the assault on the Pharos itself, and performed a ritual that destroyed the ancient device and erected in its place a monument to Tzeentch, the Architect of Fate. Within it, he placed what remained of Oberdeii. The energies of the Warp healed the young man's mind, and, obeying the Tetrarch's last order before he disappeared once more, the Ultramarines inducted him into their ranks.

Since that day, Oberdeii has become known across the Ruinstorm as the Oracle of the Pharos. His exposition to both the device and the power of the Great Conspirator have granted him a powerful prophetic gift and psychic powers. He now wanders the Five Hundred Worlds with an escort of daemons of Tzeentch and followers, both Astartes and cultists. Sometimes, he sells his services to another warlord, demanding strange payments – arcane tomes, favours, and other relics – and even sometimes fighting without demanding anything in return. On the few occasions he has taken parts in attacks on the worlds of the Iron Cage, his presence had enough of an impact for the Inquisition to grow an interest with him. He is on the list of priority targets of the Fourth Legion around the Ruinstorm.

Homeworld

Despite the horrendous destruction unleashed by Guilliman in his attempt to destroy the World Eaters and Word Bearers, the Five Hundred worlds still endure, after a fashion. Those not lost entirely to ravening hosts of daemons are coveted prizes in the endless wars between Ultramarine warbands. All of these worlds are in a state of constant flux, with immense fortresses being raised and brought down through warp-craft and more mundane means in equal measure. Yet no Ultramarine will deny that the true homeworld of the Legion remains Macragge, even ten thousand years after the Heresy. The fact that the Ultramarines have retained control of their original homeworld while the other Traitor Legions have been forced to seek new ones in the Eye of Terror is yet another source of hatred between the sons of Guilliman and their former comrades.

The Five Hundred Worlds are a catalogue of madness and corruption, but even among them, three planets stand out, both for their infamous history and the power they grant to the warlord who control them. First among these is Macragge, homeworld of the Legion. Billions of cultists live their short existences on this thrice-cursed world, serving the Dark Gods from the moment they are born to the instant their soul leaves their flesh. Macragge is covered in temples to the Primordial Annihilator in all its aspects, and almost every human – or creature whose genetic code is based upon the human form, at least – is affiliated to one of the temple. This affiliation is the only protection against the bands of cultists who roam the streets of the planet-wide metropolis in search of sacrificial victims. All temples wage endless wars against one another for the favor of the Dark Gods, with the occasional support of one of the Ultramarines garrisoned on the planet. Greatest of these temples is the Fortress of Hera, hosting the Mausoleum within which lies the body of Roboute Guilliman, preserved in stasis. The Fortress is also the seat of power of the ruling Ultramarine warlord, from which he commands the many defenses of the planet and grants audiences to out-worlders as well as his own subjects.

While there is a veneer of order on Macragge, Calth's surface is an eternal battlefield. Hundreds of warbands and daemon armies wander the desolation left behind by the Ruinstorm's birth, fighting everything that crosses their path. This endless battle is what fuels the power of Calth's ruler : the Sacrificed Son, Marius Gage, who watches over his domain from a tower raised in the place where he made his stand against Angron and Lorgar ten thousand years ago.

In Calth's underground, entire cities remain, populated by humans, mutants and other, less recognizable creatures. These arcologies are mostly left alone by the warring factions – a tacit accord that allows all groups to recruit canon fodder from them. Surprisingly, these underground cities are ruled over by mortal warlords, not their Astartes superiors. A few Ultramarines live in Calth's underworld, banished from their Chapters for various offences, but they remain in hiding, careful not to draw the attention of a Chaos Lord visiting from the surface. In orbit, the wreckage of the Battle of Calth and the many more confrontations that took place in the early years after the Heresy have combined with severe daemonic infestation to make navigation a nightmare. There are always a few paths to the surface, but it is impossible for ships to fight properly above Calth. A caste of pilots and navigators have settled among the derelict ships, lending their services to those warlords who want to bring their forces down on the planet – for a fee.

Last of the Ruinstorm's jewels, Armatura was once a war-world, a miracle of productivity and logistics that supplied most Ultramarine Chapters with recruits and materiel. It is now the domain of the Dark Mechanicum hereteks, who perform blasphemous experiments, seeking to fuse flesh, metal, and the power of the Warp. The daemon engines of Armatura are highly prized among the Chapters, and they will pay whatever price the dark magos demand to obtain them – as long as a handful of magos are added to the bargain to maintain and control the infernal creations. All warbands respect the planet's independence, some out of genuine respect, most because of the enormous orbital defenses and armies dedicated to preserving the planet's from the clutches of greedy Chaos Lords. There are several forge-cities on the planet, each under the control of the Dark Mechanicum equivalent of an arch-magos. Though they are divided by theological feuds and rivalries, they invariably put aside their differences every time their world is threatened.

Marneus Calgar, the Lord of Macragge

The throne of Macragge is ever contested by various Chaos Lords, and it is rare for any to sit upon it for long. Yet is has been more than a hundred years than Chapter Master Marneus Calgar has seized the position from his predecessor's cold dead hands, and despite many attempts, no challenger has succeeded in replacing him. Gifted with an uncanny grasp on tactics, he is also a master politician, keeping the various factions of Macragge at each other's throat in order to prevent the rise of any capable of truly challenging his power. As the wearer of the fabled Gauntlets of Ultramar, he is a powerful warrior, carrying with him the remnants of the Dark Gods' blessings upon the Arch-Traitor.

When a tendril of Hive-Fleet Behemoth reached Macragge, it was Calgar who led the defense of the Ultramarines homeworld. He fought against the Swarmlord in single combat, and though he was able to injure the creature, it proved to be his superior, and left him maimed and on the verge of death. In a surprising turn of events, the crippled Chaos Lord wasn't killed by his followers, but instead brought to his hereteks and Apothecaries, who healed his wounds and replaced what he had lost with corrupt cybernetics. Now harder to kill than ever, and with his hold on Macragge secured by his ultimate victory against the Tyranids, Marneus has started to turn his gaze outward, to the rest of the Five Hundred Worlds – and perhaps even beyond the walls of the Iron Cage …

Beliefs

Codex Chaotica

Written by Guilliman during a period of time stretching from his emergence of the Eye of Terror to his demise in the Imperial Palace, the Codex Chaotica – also known as the Book of Guilliman, the Accursed Tome, and a myriad other fell names – contains the sum of the Arch-Traitor's knowledge of both Chaos and military strategy. It is both a religious text, describing the nature of the Dark Gods, the daemons that serve them, and a tactical manual used by the Thirteenth Legion.

During the Heresy, the Codex was constantly updated, each book across the galaxy altering its contents to match the copy Guilliman himself was writing into. And yet, even after Guilliman's death, the book has continued to update itself, with new rites and knowledge about other Neverborn appearing within its pages. Many Ultramarines take this a sign that their father yet live, and that he communicates with them through the Codex, guiding them in their eternal war against the Imperium. They embrace its teaching fanatically, hoping to become closer to Guilliman through it.

In the past ten thousand years, many Inquisitors have attempted to secure a copy of the Codex, seeking to use the knowledge within its pages against the Ruinous Powers and their minions. All of them went insane as the madness of the book poured into their souls, and while many took their own lives or were reduced to gibbering wrecks that were put out of their misery, many others were consumed by the lies of Chaos and went rogue. In response, more puritanical members of the Holy Ordos have taken up the policy of systematically destroying every copy they come across, a practice that was already followed by the warriors of the loyal Legions since the Heresy itself. Yet in spite of their efforts, new copies are written on Macragge, by minions of the Dark Gods that sit beneath Guilliman's mausoleum and are inevitably consumed by the unholy knowledge they pour onto the pages of human skin upon which they write in blood with quills made of the bones of loyal Space Marines.

To be an Ultramarine is to be not only touched by the madness of Chaos, but consumed by it. While other Chaos Marines retain a modicum of sanity – often just enough to know, deep inside, that they have become monsters, and hate themselves for it as much as they hate most of the rest of the galaxy – the sons of Guilliman glorify in their unrivalled corruption. They do not commit atrocities for shock value, hoping to break the enemy's morale : they do it because it pleases them. They do not embrace the path of Chaos for the power it brings, but because they genuinely believe in its dark philosophies.

As a Legion, the Ultramarines follow the path of Chaos Undivided : they worship all four Dark Gods as the absolute masters of the galaxy, reflections in the Sea of Souls of Mankind's true nature. Through the union of the Materium and the Warp, they believe they can achieve a state of perfect harmony, with the anarchy of the Warp controlled and directed by the will of immortal, transcendent souls. Possession is an illustration of that belief, as is the Ruinstorm and other Warp Storms. To them, daemonhood is the ultimate form of existence, and the destiny manifest of all Mankind – once it had shed itself of the unworthy and the weak.

This belief is the reason why the sons of Guilliman seek to become Secondborn and Daemon Princes far more eagerly than other Traitor Legions, despite the risks. Similarly, Chaos Spawns are numerous among the Ultramarines, due to their relentless pursuit of daemonhood. They are seen as expressions of the Dark Gods' will made manifest, and reminders that there is a price for failing to match the standards of Ascension. Of course, the displeasure of the Dark Gods toward the Thirteenth Legion makes such dark apotheosis very rare among the Ultramarines. But rather than despair over this fact, the sons of Guilliman see it instead as a test, ensuring that only the truly worthy are granted immortality and daemonic power.

Despite the common worship of the Primarch and the following of the Codex Chaotica, there are still doctrinal differences in the Thirteenth Legion. Many Ultramarines have dedicated themselves to a single Dark God, believing their patron to be superior to the rest of the Four or simply more aligned with their own inclinations. Some of them remain with their original Chapter, though they are often ostracised by their more orthodox brethren. Others gather in groups following the same Power, under the banner of a favored champion of Chaos. Wars between warbands following opposed gods as a way to gain favor are common, and entire daemon worlds are divided between warring armies of each Dark God, each warlord seeking to conquer the planet and dedicate it to his patron.

It is somewhat ironic that these Chapters who have chosen to follow a single of the Dark Gods are viewed as heretics by many of their brethren, while they are those with the most chance to actually reach apotheosis. Indeed, while it is not unheard of for the Ruinous Powers to elevate one of their champions to daemonhood together – Vulkan, Corax, and the Tetrarchs come to mind – such an occasion is exceptionally rare, and the individuals in question shaped the entire galaxy through their dark deeds. Those who dedicated themselves to Khorne, Tzeentch, Nurgle or Slaanesh stand a much better chance to be selected for ascension. Of course, given the length of the odds involved and the sanity of both the Dark Gods and their worshippers, the very concept of "chance" holds little sway in the dealings of Chaos.

As was stated before, all Ultramarines have the deepest respect and love for their father, even those who were created long after Guilliman's death at the God-Emperor's blade. In many warbands, this translates into a worship of the Arch-Traitor. Altars are raised and adorned with his image, and sacrifices offered for his favor. Many believe him to be alive in some way, and still consider him to be the leader of the Legion from beyond the veil of death. Only in Chapters that are not aligned with any of the Ruinous Powers is such a worship openly practiced, for it has no return : there has never been, to the Inquisition's knowledge, an occasion when the Arch-Traitor has actually rewarded one of his sons for his devotion. And yet, even after ten thousand years of silence, there are still Ultramarines who pray for the blessing of Roboute Guilliman, whose treacherous blood runs in their tainted veins.

Combat doctrine

'Corrupt their hearts with the whispers of Slaanesh.

Twist their minds with the secrets of Tzeentch.

Poison their flesh with the plagues of Nurgle.

Spill their blood with the strength of Khorne.'

From the Codex Chaotica, Eighth Chapter, Ninth Verse

As with their beliefs, Ultramarines Chapters have varied approaches to warfare. Each warband has its own preferred methods, depending on its leader's skills, the resources at his disposal, and which aspect of Chaos Undivided its members follow. In many ways, the Ultramarines hold all of the strengths of the other Traitor Legions combined – but without the Legion-wide favor of the Dark Gods, each of their facet is but a weaker copy of the Traitor Legion it desperately apes.

Chapters dedicated to Khorne will launch brutal, ruthless assaults on their enemies, heedless of the cost, offering their own blood and that of the enemy to render the veil and bring forth hordes of Daemons of the Lord of Skulls. Those who have been welcomed into Nurgle's embrace spread out contagion and decay before them, bringing thousands of diseased slaves and hurling them at the enemy so that their deaths will infect the foe. Warbands led by servants of Tzeentch use deceit, treachery and foul magics to turn their enemies against one another before striking the killing blow. As for the Chapters aligned with Slaanesh, their warlords delight in the choreography of war, and surprisingly prove to be some of the most tactically-minded of the Dark Prince's disciples, their mutated brains rewarding master-strokes with chemically-induced pleasure.

Most dangerous are those Chapters who do not follow any particular Dark God, but the Primordial Annihilator as a whole. Less consumed by the rivalry that allegiance to any of the Four breeds, they can act with more cohesion on the battlefield. While their individual warriors may lack the unholy strength granted by a Dark God's "blessing", they make up for it with an abundance of Possessed Marines and Dark Mechanicum constructs.

The Ultramarines fight most of their battles against each other or the Neverborn armies that populate many of the Five Hundred Worlds. The complete anarchy of these conflicts has trained them to be supremely adaptable, for there is no telling what manner of foe they might fight next. While they rely on the Codex Chaotica for their esoteric and tactical lore, the sheer amount of tactics that have been added to it over ten thousand years more than makes up for the lack of innovative thought displayed by many sons of Guilliman. On the battlefield, their leaders act less like strategists and more like cogitators, following a succession of instructions written in their holy book without understanding the meaning behind each action. It isn't rare for a Chaos Lord to misinterpret an instruction, though, and the results are often catastrophic for the warband – though on at least one occasion, such a mistake instead ended up winning the day for Chaos against Imperial forces.

Over the millenia, the Iron Warriors manning the Iron Cage and their allies Inquisitors have grown used to repel the Ultramarines' attempts at breaking free. Every century or so, a warlord within the Ruinstorm calls for a Black Crusade, and gathers as many allies around him as possible before launching a massive assault on one of the fortress-worlds guarding one of the Warp roads leading out of the Ruinstorm. While it is possible for a handful of ships to slip through the Iron Cage unnoticed, or simply by running fast enough to escape pursuit, the only way for a true armada to leave the Cage is to conquer or destroy a world-fortress, removing the obstacle so that the forces can emerge from the Ruinstorm in order. Sometimes they will attempt to corrupt some of the Iron Cage's defenders, hoping to make the wardens open the gate of their prison. On a handful of occasions, this has actually worked, with Imperial officers and even a handful of Iron Warriors betraying their oaths to the God-Emperor. But the Inquisition has agents on all worlds of the Iron Cages, and they are ever watchful for signs of treachery, while the Fourth Legion's Chaplains are equally vigilant.

Cato Sicarius, the Warrior-King of Espandor

If there is one Ultramarine that showcases just how far the sons of Guilliman have fallen, it is Cato Sicarius. Ruler of the daemon world of Espandor, near the edge of the Ruinstorm, Sicarius is a Chaos Lord of Slaanesh that is all but consumed by the power of his Dark God, in its most selfish and depraved incarnation. Born on Macragge itself, among one of its most powerful priestly bloodlines, he was chosen to become an Ultramarine as much because of his skill with a blade and relatively pure genetics than because of his family's influence. His immense pride and self-importance caused him to be quickly marked by the Dark Prince of Chaos, and he rose through the ranks not because of his tactical acumen but almost exclusively because of his skill with a blade. In time, he became the champion of Marneus Calgar, the Chapter Master ruling over the Ultramarines' homeworld – a position of extreme honor in the Legion.

But simply being a champion wasn't enough for Sicarius' ambitions, and he sought to overthrow his lord and replace him as master of Macragge. His coup failed pathetically when half of his followers turned against him on the eve of the confrontation between him and Marneus. For his betrayal, Marneus banished him from the homeworld with his followers, confident that one of them would kill the upstart champion soon and spare him the trouble of ordering one of his brothers killed himself.

As the Chapter Master had predicted, Sicarius' confederates turned on him almost as soon as their ship left Macragge. But the champion managed to defeat all of his would-be assassins, and quickly found himself the only Legionary aboard the Chaos ship. After months of errance, the tides of the Warp delivered him to the world of Espandor. The world was under the control of several Chaos Lords of Khorne, who had formed an uneasy alliance so that they might focus their efforts on their raids on the Iron Cage in the name of their god. Sicarius' ship crashed onto the planet, with the Chaos Lord as the only survivor. When the salvage parties of Espandor's Blood Lords arrived, he let himself be taken prisoner and brought to the city of Corinth, from which the lords of Khorne ruled the planet. There, he freed himself and escaped, before allying with a Corsair Queen named Kaarja Salombar. Together, they overthrew the eight Blood Lords, and turned Espandor to the worship of Slaanesh. Ruling alongside the pirate queen, Sicarius has since led a series of raids against both other daemon worlds and Imperial targets, always choosing targets that were poorly defended and with a lot of potential slaves for the flesh-pits of Espandor. Despite his position of power, he is hated among the Ultramarines for his arrogance – despite his exile, he still genuinely believes that he is destined to rule the Ultramarines and bring them to the worship of the Dark Prince – and leads a warband of corrupt mortals rather than other Chaos Marines.

Recruitment and Geneseed

Despite the hellish conditions of the Ruinstorm, many of the Five Hundred Worlds are capable of sustaining a human population. None of them are spared the touch of the Warp, however, and the rampant mutations among these souls, practically damned before they are even born, make it difficult to find subjects genetically strong enough to survive the transformation into an Astartes. Still, with hundreds of worlds to draw upon, the Ultramarines have managed to maintain their numbers through ten thousand years of brutal infighting and failed attempts at breaking free of the Iron Cage. On the occasions when an Ultramarine warband breaks free of the Iron Cage and conquers Imperial territory, the Apothecaries among its number will echo the ancient practice of the Legion, taking the children of their defeated foes to add them to their genetic stock. This influx of untainted blood is probably the reason – beyond the use of Warp-craft – that any new Ultramarines can be created at all.

Each Chapter has its own group of Apothecaries, tasked with ensuring the future of the warband. They harvest the gene-seed of the fallen and implant it into new Chaos Marines, but they are also tasked with finding human specimens genetically pure enough to allow the transformation. Wars have been fought in the Ruinstorm between Chapters for control of untainted recruiting grounds. Ironically, these battles often result in the human population being infected with the corruption of Chaos, making the losses suffered by both sides entirely pointless.

No Ultramarine lives who is free of mutations, but all of these are inflicted by the Dark Gods to reflect the warrior's inner soul unto his physical form, not due to a corruption of the gene-seed itself. Analysis of progenoids harvested on dead Ultramarine raiders has revealed a general weakening of the various biological mechanisms that usually protect Astartes from the touch of the Warp, explaining some of the higher mutation ratio encountered among the Thirteenth Legion when compared to other Traitor Legions.

Although it hasn't been proven, there is a persistent theory in the Inquisition and the magos biologis of the Adeptus Mechanicus that the Ultramarines' gene-seed suffers from a mutation that dampers free will and self-awareness through a combination of hormones that weaken cerebral activity in some regions of the cortex. According to that theory, when combined with a life spent in the Ruinstorm, this makes it so that only exceptional individuals can resist the erosion of their selves into mindless following of the Codex Chaotica. If that theory were to be true, it would be just one more punishment inflicted by the Ruinous Powers upon those who were once their favourite servants.

The Evocatii

With the Five Hundred Worlds to call upon, he Ultramarines still have the facilities and resources required to create Legionaries in conventional manners – though with some daemonic help in their technology. And yet, there are many fallen Apothecaries who continue the unholy practice of the Evocatii, begun during the Heresy's preparation. All Traitor Legions deviate from the standard procedure of Astartes creation, be it because of necessity or perversion. But the Evocatii are different in that they are never intended as Astartes at all. Among the Chapters of the Thirteenth Legion, those of them who retain their awareness are seen as second-class warriors, forever beneath the better-born Legionaries. As for those who are wholly consumed by their bestial nature, they are regarded as no different from battle-servitors and other pieces of equipment.

Some Evocatii are the fruit of blasphemous union of gene-seed and xenos essence, while others have their bodies almost entirely replaced by Dark Mechanicum's augmetics. There is some of Guilliman's genetic legacy in all of them, but it is diluted : one progenoid gland, normally used to create one Space Marine, can be used to create a dozen of these "thin-bloods", as they are also sometimes called among the Ultramarines. Despite the contempt most Ultramarines have for the Evocatii, many warlords make use of them, either as support for their true warriors, or to fill up their ranks after a string of defeats.

Warcry

The Ultramarines don't have a common war cry any longer. One of those which are used across several warband is 'For the Primarch and the Dark Gods !', as is 'Death and Ruin !' in a twisted parody of the Legion's original war cry 'Courage and Honor !'. But as the level of loyalty to the Pantheon and the Arch-Traitor changes, so do the warcries employed. Many Ultramarines have been reported to simply laugh insanely as they charge enemy lines, their vox-speakers amplifying the sound into a cacophony that can terrify even the bravest mortal man as his soul is faced with the very manifestation of Warp-induced madness. Other times, they broadcast the names and titles of their leader, seeking to increase the warband's reputation among the Imperium – and through it, its standing in the eyes of the Dark Gods. Warriors who seek glory for themselves will shout their own names, while others sing unholy hymns of praise to their daemonic masters, listing the name of their patrons so that their victims know to whom their souls will go.

Such is the corruption of the Ultramarines that merely listening to them can – and has many times in the past – drive someone into heresy. The foulness of the Chaos Marines' soul is rumoured to overspill from their physical presence, tainting all those who establish contact with them – even if that contact is limited to hearing their insane braying. To counter this, the Iron Warriors have installed powerful speakers of their own on their garrison worlds around the Ruinstorm, and all human soldiers are required to wear ear protectors whenever faced with the treacherous sons of Guilliman.

I am alive.

My body is frozen, suspended out of time in the moment before my hearts beat their last. My soul lies forever on the threshold of death, halfway between the world of flesh and blood and the realm of thoughts and beliefs. The pain of my wounds fills my every cell, its intensity never fading for one moment. And yet, despite this unending torment …

I am alive.

Though my eyes are blind, I see the galaxy with a god's sight. The souls of those who carry my blood within them are candles in the vast darkness of space, and I watch them as I try to ignore the agony of my broken body. They have grown weak in my absence, even weaker than they were when they failed me all this time ago. They think me dead, and they pray for my resurrection, blind to the truth that is exposed before them …

I am alive.

My loyal Tetrarchs walk in the shadows of reality and unreality alike, listening to my silent voice and doing my will. They seek out these few among my sons who are yet worthy, and guide them down the path of greatness. They hunt down those who stand in the path of my return, and usher in their downfall. The Imperium thinks me dead, but my father on his throne knows …

I am alive.

The thorns I left in the Imperium's side heed my call in their sleep, and plot to bring its corrupt edifice down from within. Many have fallen prey to my father's hounds, but those who remain are strong – stronger than most of my failed sons will ever be. They hide in the deepest shadows and wield the knowledge and power I bestowed upon their forebears millenia ago. Despite believing me gone, they still hold true to their predecessors' oath, and for that they shall be rewarded …

I am alive.

My treacherous son seeks to replace me still, gathering under his banner the foolish and the deluded, hoping to reclaim the power and glory he once possessed. He believes himself to be chosen by the Dark Gods, that it is his destiny to claim the throne that is rightfully mine. But he is only a punishment, an obstacle placed in my way for me to surpass. He is not my heir – he cannot be my heir …

I am alive.

My brothers in the Eye play out their parts in the Great Game, blinded by their own petty quests to the ultimate prize. They have become strong, but I cannot allow them to become too strong for me to control, and I silently guide others to oppose them and their sons. Despite all their power and knowledge, they too think me dead and curse my name, but they are wrong …

I am alive.

The princeling of shadows slithers in the dark places, still fooling himself into believing he is the Gods' chosen, while deaf to their laughter. Still he covets my crown, seeks to reclaim the mantle I took from him long ago. He does not realize that he was never anything more than a place-holder, a vessel for a power that is now mine. His designs are obscured from my sight, but he alone knows …

I am alive.

My will spreads out across time and space, reaching out to those who are worthy of serving me. This time, I will not repeat my mistake. I will not gather all that I can to me, hoping to overcome my foes with mere numbers. Each of my pawns shall be a king in his own right, and they shall lead their armies in my name. For I will rise from my throne. I will rise, and finish what I started …

I am alive !

---

AN : hello, dear readers.

At long last, it is done ! This is the longest Index Astartes to date, and it will probably remain so until the very end of this fic. Really, over 23,000 words, I really went overboard with this one - but there was just so much I wanted to put in it, I couldn't help myself. I hope you enjoyed it, since this is arguably the most important part of this entire fic.

In the canon universe, the Ultramarines are the noblest of all - or at least, that's how they are portrayed within the Imperium. Like many fans of the Warhammer 40000 universe, I was quite annoyed at the aura of perfection that clung to them until recently, where the Horus Heresy works have portrayed them in a more flawed manner. Still, they remain honorable warriors, and so, in accordance to my protocol in this story, I had to make them as ignoble here as they are noble in canon. I think I succeeded. The idea of using Be'lakor came from the fact that he is a really interesting character, and that creating the Champion of Chaos was is job in the Warhammer Fantasy universe (read the novels about Archaon for more details. They are kinda confusing, with the timeline all over the place, but still very good). His part here is an hommage to that, though the end result was very different. It also allowed me to put a lot more threads for the End Times, which I am looking more and more forward to as this story progresses.

There was a lot of positive feedback for the last chapter, which is always nice. Zralock asked if we would see more of Eldrad, and to be honest, I haven't really thought about it. He is very useful to modify events, but he is also a character in himself, with motivations and beliefs. The BL kinda uses him as a plot device to justify the presence of Eldar whenever they want (just look at his part in the recent book Throneworld, I mean, the book is good, but come on), and I want to try and do better.

I was really excited about Battlefleet Gothic : Armada, the new PC game placed in the WH40K universe and allowing you to control the great starships of the Imperial Navy, as well as other factions. Unfortunately, I checked, and my PC isn't powerful enough to run it properly. That's a shame, because the game looks really awesome, and from what the trailers have shown, it really respects the lore. At the very least, it has motivated me to try to write something with ship-to-ship action - perhaps in Warband of the Forsaken Sons, once I am done with the current arc.

My exams are coming up, and I also want to send a submission to the Black Library before the window closes (I know it is very highly unlikely my submission will be selected, but a man can dream), so it will be some time before I next publish something on this website. I have an idea to combine the extracts I won't send into a short story (I have already nine submissions ready to choose from), and after that, I will return to the Forsaken Sons.

As usual, if you see any incoherence or mistake, please tell me either in a review or by PM. I have already been warned several times about mispellings and name mistakes, so don't hesitate. Same thing if you have any questions or suggestions for the next Index, where we will meet the Death Guard, on whom I have written very little so far.

And please, go check Nemris' amazing artwork on his deviantart page. These are some really good illustrations of my universe that he has created.

Zahariel out.