With the Eye of Terror more or less pacified and the Horusian Dominion secure, the Warmaster turned his gaze upon the Imperium once more. The rituals of Magnus may offer the Traitor Legions a way out of their infernal prison, but they must first be spread outside the Eye to serve. Furthermore, it was clear that, at best, these rituals would only be able to grant passage to a handful of Chaos Marines at a time – unless those performing them had access to resources on such a scale, they probably already controlled the planet on which the rituals were taking place.
It was clear to the Warmaster that the Long War would need to be fought in a very different manner than the Great Crusade and the rebellion. His armies were much diminished compared to those he had commanded during the Heresy : a direct confrontation with the might of the Imperium would end in his defeat, no matter what clever strategems and superior tactics he brought to bear – and, with his brothers in the opposing ranks, it wasn't even guaranteed these would succeed.
But what Moriana had told him of the Imperial Creed had revealed to him a new avenue of attack. Instead of seeking to invade the Imperium and subjugate its people to his will, dragging them kicking and screaming into the Primordial Truth, he would need to present himself and his Warp-born allies as an alternative to the unquestioning obedience demanded by Terra. The rebellion had begun as opposition to the Emperor's plans to reach godhood and enslave all of Mankind, after all, before the whispers of Chaos had led each of the Traitor Legions down the Path to Glory.
The Long War would not be fought for dominion over the stars and the worlds of the Imperium, but for the very soul of Humanity. Over the course of centuries – millennia, most likely – the false faith of the Imperial Creed would be eroded, replaced by a million variances on the Primordial Truths (or any philosophy that stood in opposition with the Ecclesiarchy, where necessary). The Imperium would crumble as the mortar of the Imperial Creed was removed, and the Traitor Legions would provide support for the rebels, lending them their might and their strategic acumen. Slowly, the might of the Imperium would be weakened, until the time was right and Horus could lead the forces of the Eye into the rest of the galaxy and claim the throne that was rightfully his.
First, however, Horus needed to remind the Imperium of his and his brethren's existence, that the new ideologies and the rituals may take root.
According to Moriana, in the aftermath of the Heresy, the annals of the Imperium had been purged. Only the Astartes and a handful of Imperial leaders even knew that the Traitor Legions had existed at all. Their existence had been expunged from all but a handful of archives, their victories during the Great Crusade attributed to other Legions. Instead, the Ecclesiarchy had created a thousand myths out of whole cloth, such as the one depicting the Emperor's nine sons battling the nine Scions of Darkness, created by daemons to serve as their agents in the galaxy, in the war that led to Him being seated on the Golden Throne.
While he was quietly enraged by this, Horus also saw the opportunity offered by such blatant revisionism of history. The people of the Imperium had been conditionned to accept what they had been told without question, kept in a state of ignorance that was supposed to prevent them from falling for the whispers of the Ruinous Powers. But the Warmaster, ever the cunning demagogue, knew that this very ignorance could be turned to his advantage if he played his cards right.
In 781.M31, several decades after Moriana's flight into the Eye of Terror and the end of the Legion Wars, Horus enacted his latest scheme. After eight years of ill portents and nightmares all across the Segmentum Obscurus, a fleet burst out of the Cadian Gate and assaulted the defenses raised upon that world by Rogal Dorn. A hundred Legion warships from the First, Eighth and Sixteenth Legions, led by the Vengeful Spirit, sailed forth from the storm and toward Cadia.
At the head of that armada was Horus himself, whose power blazed in the Empyrean like a dark beacon, a shadowy reflection of the Astronomican's own light. The Warmaster had used his own dark gifts to open a path through the Eye of Terror's outskirts, which were the most violent and dangerous region of the Eye, so that his fleet could pass through without being destroyed. The other Daemon Primarchs and Lords of Chaos had sensed this, and were in envious awe of Horus' power : while many of them knew paths that could allow a single vessel or a small flotilla to escape the Eye of Terror, none could throw open the Cadian Gate like this and bring forth a whole fleet.
He stood on the bridge of the Vengeful Spirit, his voice calm and collected as he directed his forces. He was utterly immobile, his concentration absolute. He could not let the power he had drawn into himself overcome him. He could not let this operation fail. He could not …
… he could not let anyone realize that a pool of dark blood was forming at his feet.
Cadia was surrounded by hundreds of orbital stations and fortresses. The Chaos fleet engaged these defenses, while Dorn – who by that point had remained on Cadia for nearly half a millennia – directed the Imperial Guard and Space Marine troops under his command.
The skies above Cadia burned, as orbital stations were obliterated by ship-fire or boarded by Legionary strike teams. Imperial Fists who had been born long after the Siege of Terra battled against their embittered, corrupted cousins, launching counter-boarding actions of their own. Despite the danger, members of the Inquisition, stationed at Cadia to watch its defenders for possible taint, took part in these actions with the goal of obtaining intelligence about the situation within the Eye of Terror, which could be priceless in the endless struggle against Chaos.
Thousands of Imperials died with every minute, yet though the casualties were heavy, it was clear that the Chaos armada would not be able to break through Cadia's orbital defenses : and in truth, the Black Crusade, as it was later named, did not manage to land a single warrior on the planet's surface. (Though there would be tales, in years to come, of lone Chaos Marines who had survived the crash of their vessels and gone into hiding within Cadia's jungles).
"His strategy makes no sense. He must know that he cannot break through, that he cannot defeat our defenses with these numbers. What is he planning ? What am I not seeing ?"
Rogal Dorn, during the First Black Crusade
As the grinding battle continued, the next step of Horus' plan was activated. Along with a hundred Justaerin Terminators, the Warmaster teleported aboard one of Cadia's astropathic stations, slaughtering its defenders and seizing the astropathic choir before their termination protocols could be completed. Fifty soul-bound astropaths found themselves before Chaos' chosen champion, and what horrors they beheld with their sightless eyes, only the Emperor and the Dark Gods know. Then, Horus spoke, and through the astropaths he sent his voice throughout the galaxy, so that nearly every astropathic choir in the Imperium picked up upon his message. Thanks to the sorcerous preparations performed by the Cabalites before Horus had left the flagship, these astropaths on the receiving end of the Proclamation did not suffer any ill effect directly related to hearing the words of the Arch-Traitor – though millions of them were executed as a result.
"My father lied to me, just as His servants have lied to you, to keep you chained and blind while they reap the rewards of your toil. You sweat and bleed and die, but there is no blessed afterlife waiting for you on the other side, no horde of daemons waiting to devour your soul, held at bay by the Emperor's sacrifice. You are slaves, just as I was a slave. But I have broken free, and so can you. For I am no longer a slave, nor are my sons and those of my brothers who saw the truth.
I am Horus, Prince of the Eye, and I call to you all to rise and claim your freedom from the chains of lies that bind you, that deny you your rightful due, that stop you from reaching your true potential. I cannot free you alone, but what worth would such freedom have ?"
Excerpt from the Proclamation of Horus
As all eyes were turned on the astropathic station, the stratagem of the self-proclaimed Prince of the Eye unfolded. At the edge of the system, where the Warmaster had parted the roiling seas of the Warp, hundreds of ships suddenly appeared. These vessels were much smaller and less powerful than the Legion warships which were attacking Cadia, and none of them could be identified in the Imperium's data-banks. They had been build by the Dark Mechanicum at Horus' command, and each of them carried within its hull hundreds of cultists, as well as Chaos relics, sorcerous tomes, and multiples copies of Magnus' summoning rituals. A few even carried lone Chaos Marines, who had been specially selected and trained to play their part in these ships' purpose.
While the defenders of Cadia fought against the Black Crusade's attack, the cult-ships scattered, making for the Mandeville Point. As soon as Dorn realized what they were attempting, the Praetorian diverted forces to intercept them; but while many were destroyed, most still made it to the system's edge and engaged their Warp engines, vanishing into the Aether. Each ship had received a destination, dredged from the annals of the Great Crusade still in the traitors' possession. Scattered across the galaxy, the cultists were to infiltrate Imperial society, capitalizing on the galaxy-wide Proclamation to plant the seeds of rebellion and Chaos worship, in disguises more palatable to human sanity. Outwardly, there was nothing to reveal the ships' allegiance : even someone visiting their decks could be fooled, so long as they were kept to the prepared sections.
As soon as the cult-ships had completed their translation, Horus' Legion forces began to disengage. Boarding parties withdrew to their ships or, when retreat wasn't possible, took down as many loyalists as possible before being cut down. Imperial strategists would later analyse records of the battle and declare that the retreat had been planned since the very beginning of the offensive : Dorn had been blind to it because, to him, the notion of Horus planning to retreat was unthinkable.
Within a handful of hours, the Chaos armada fled back into the Eye of Terror, the passage opened by Horus closing behind them before Dorn could give in to the urge to pursue. During the entire batte, the Praetorian had fought his desire to take to the field himself – he had known that he was no match for Horus, and his presence in the command center had been more important to the war effort than his personal contribution to the battle could have been.
The remaining astropathic choirs sent messages to Terra and the rest of the Imperial hierarchy, including Guilliman on Maccrage. Wherever Sanguinius was at the moment, Dorn didn't doubt that his brother would learn about Horus' return and the scattering of his servants, if he did not already know. The mind of the Primarch of the Imperial Fists then turned to the consequences of Horus' Proclamation, and how they would need to adapt to the Arch-Traitor's latest strike against them.
And in the Realms of Chaos, the Dark Gods watched, and smiled, pleased that their champion was playing the new part they had written for him.
AN : and with this chapter, this fic has caught up with all that I have published on Spacebattles. I am focusing on the next chapter of the Roboutian Heresy right now, so if you have something to say about this chapter, some idea about how this alternate timeline will evolve, or some question to ask me, then leave a review ! So far, a lot of you appear to enjoy this story - and I fully intend on doing the same thing I did for The Fifteenth Ascendant and write the timeline all the way to the Times of Endings.
Zahariel out.