"What we're showing next is after the Unification Wars." D told the audience, who seemed interested in what happened to Humanity in this period in the timeline.
"I wonder what the Emperor did after conquering Earth or should I say Terra?" Izuku commented.
"The next logical step is expanding into the Galaxy." Yamamoto said.
"Conquering a planet is much simpler than conquering a galaxy." Esdeath said while imagining herself ruling her world.
"This Emperor has ambition, I'll give him that." Kaido said.
The Great Crusade (798.M30 — 005.M31) was a brief age of rebuilding and reunification following the complete regression of mankind during the Age of Strife. It was a time when the Emperor still lived in the conventional sense and led his race in person. It followed the Emperor's conquest of Terra in the Unification Wars and lasted roughly from the conquest of Earth's moon to the Battle of Isstvan III and the beginning of the Horus Heresy.
"The Horus Heresy?" Oobleck questioned.
"That does not sound good." Ichigo commented.
"Could this be the rebellion we heard mentions of?" Izuku asked.
"We'll learn about the Horus Heresy in due time." D replied.
The Early Crusade
Part of the Emperor's vision of human unification was the Primarch Project, meant to be the creation of 20 superhumans to lead the Emperor's forces to reclaim the galaxy in his name. It also saw the creation of the Space Marine Legions from the gene-seed samples that survived the scattering of the Primarchs by the Chaos gods. These forces would play the major role in the upcoming Great Crusade alongside the Imperial Army, Titan Legions, Legio Cybernetica, Sisters of Silence, and Custodian Guard.
"The Custodians are the Emperor's personal guard. They are described as works of art." Z explained.
"Works of art?" Jaune asked, furrowing his eyebrows.
"Why would they be called that?" Ruby added.
"You'll find out later." D replied.
The subsiding of the warp storms plaguing much of the galaxy coincided with the end of the Age of Strife. With warp travel possible again, the Emperor was able to begin the Great Crusade which would create the Imperium. Even before the warp storms and the Age of Strife had ended, the Emperor had begun to make plans for the Great Crusade. These plans included the creation of a far more advanced form of power armour required for the conditions of deep space and alien worlds.
The scientifically minded members of the audience took note of this.
After securing Luna and then Mars, he began a great building project, reconstructing the industries and production facilities he would need to construct and maintain a great space fleet, sufficient to carry his legions all the way to the edges of the galaxy. Mars, due to its advanced technology and manufacturing infrastructure, became the center of this development, producing, along with ships, the arms and armor his warriors would be equipped with.
Martian Manhunter reacted with dismay at how the version of Mars in that universe looked.
Saturn, Neptune, and Jupiter fell to the Emperor next, its inhabitants liberated from cruel alien overlords. Finally, the Imperial War Fleet broke out of the Sol System after completely annihilating the "false world" of Sedna.
"A false world?" Melissa asked.
"I won't be surprised if there were aliens who can create artificial planetoids." Nezu mused.
The Crusade begins
His fleet constructed, he forged out into the depths of space, seeking out his Primarchs and spreading the name of the Emperor. Throughout the following millennium, he gradually reclaimed his Primarchs, and slowly united humanity under the Pax Imperialis. World after world fell to the Emperor's forces, at first the Legio Astartes and Custodian Guard and later the Imperial Army, Sisters of Silence, Collegia Titanica, Legio Cybernetica, and others. Tyrants and false-rulers of thousands of worlds were overthrown by Imperial forces, who quickly outlawed religion and dogma by decree of the Emperor himself. Orks, Eldar, Hrud, Slaugth, hideous Warp entities, and many other lesser alien races were all defeated and driven back in a seemingly unstoppable tide of conquest. Worlds whose human population had become too corrupted or mutated were simply exterminated from orbit.
"We'll talk about those races later, but to summarize: The Hrud are a race of aliens that can manipulate time to an extent and the Slaugth are more akin to millions of worms shaping themselves into a humanoid form." D explained
Most of the audience were disgusted and frightened by the descriptions of those aliens.
"The Hrud manipulate time?" Flash remarked.
"Yes and they do it by generating entropic fields that severely age anything caught in it." D explained.
"Now I regret asking…" Flash mutters.
"And the Slaugth are made up of worms?" Weiss asked.
"Yes." D replied.
"Gross!" Yang commented as Weiss turned slightly green.
Izuku however noticed something.
"Wait, did the Imperium actually exterminate human populations?" He asked fearfully.
"Yes they did because of various reasons." D replied.
"Why?" Izuku said, his voice had gone to a whisper.
"Well greenie there were human worlds where the people were irreversibly corrupted either by aliens or Chaos thus to stop the contamination from spreading the Imperium erased them from the census." Z answered with a grin.
Many in the audience were just as shocked at this revelation as Izuku.
The expressions of the Justice League and Pro Heroes were grim, the Straw Hat Pirates and Beacon students were silent, the members of Fairy Tail and Sabertooth were disgusted and the others were stoic.
In the early stages of the Crusade, the Imperial forces were divided into three main thrusts, one commanded by Horus, the other by Ferrus Manus, and the last by the Emperor himself.
"Horus is mentioned again…" Ichigo said.
"We will find out more about him later." D said.
"Trust me when we cover him it'll be a doozy!" Z smirked.
As each Primarch was discovered, he was given control of his own Legion of Space Marines. As more of the Empire was carved, the Emperor's forces were spread more and more thinly. Eventually the need for Space Marines was greater than the supply. As such, Accelerated Gene Culturing was necessary to provide sufficient legions. Unfortunately, this process was unstable and led to flaws in the gene seed of the legions. This would lead to such afflictions as the Red Thirst and various mutations in the Space Wolf gene seed.
"The Red Thirst?" Jaune questioned the hosts.
"Basically, it causes the Astartes to crave human blood. Kinda like vampires." Z said with another unsettling grin.
That already disturbed them, but then Z made it worse, "And the Space Wolves sometimes mutate into monsters known as the Wulfen. So much so that they had to find Russ to stabilize them."
"Great! Those Space Marines are vampires and werewolves too!" Denki said sarcastically.
"So scary…" Minoru said while shivering.
The Crusade lasted for around two hundred years. At its peak, it had over 4,300 Expeditionary Fleets involved in galactic conquest. The Great Crusade reached its apex with the great victory by Horus against a massive Waaagh! of Orks in the Ullanor Crusade. After this victory the Emperor declared Horus Warmaster, or acting Supreme Commander in his stead. Having seen most of humanity reunited the Emperor returned to Terra, where he began his secret project.
"What was the Emperor working on?" Ruby asked the hosts.
"He called it the Imperial Webway. The Emperor meant for it to reduce humanity's reliance on the Warp." D explained, "The Webway itself was a series of tunnels that existed in neither the Warp nor realspace, allowing for faster than light travel.
"And then Magnus just had to ruin everything." Z sighed as he rested his head on his hand with D nodding.
Izuku was about to ask the Hosts about what Magnus did but D shook his head.
"No spoilers." Z said while wagging his finger.
Towards the Great Crusade's end came a period of political consolidation. The Legions were at this point dispersed across the galaxy, many acting as garrison forces rather than campaigning armies. The Legions had been battling constantly, especially the Iron Warriors, struggling under the monotony of siege warfare and garrison duties. A large bureaucracy overseen by Malcador and the Council of Terra formed to manage the newly conquered territories. This bureaucracy often clashed with the Astartes military establishment, and tensions began to run high when it became apparent that the Emperor intended to have Malcador's Terran Council rule over the nascent Imperium and not the Legiones Astartes.
Akainu grumbled at the fact that bureaucracy was interfering with the Imperial military.
Green Lantern John Stewart sighed, knowing what it was like for the Government to meddle.
Natsu was reminded of the times the Magic Council butted into Fairy Tail's business.
Also, without the Emperor's guidance the Primarchs that had previously friendly rivalries were beginning to develop into dangerous feuds. Some of the Primarchs had reached the point of intolerance with one another, others like Magnus the Red had simply become isolated in the confusion of the Great Crusade. Already the Word Bearers Primarch Lorgar had secretly turned against the Emperor decades before the Crusades end after the destruction of his "perfect city" of Monarchia by the Ultramarines. Meanwhile Leman Russ clashed with both Angron and Lion El'Jonson. Perturabo was shunned by most due to the nature of his hand in the Crusade and was in turn envious of Rogal Dorn. Konrad Curze also had a disagreement with Dorn that escalated into a brutal surprise attack that left Dorn badly injured and unconscious. This mistrust and hatred would form the linchpin of the Horus Heresy.
"Let's just say shit hit the fan for the Imperium." Z offhandedly mentioned.
"You don't say?" Weiss replied sarcastically but Z ignored her.
Noteworthy Battles & Campaigns of the Great Crusade
First Pacification of Luna — The first major battle of the Great Crusade.
Sedna Campaign - The whole of the Sol System is reclaimed.
The Battle of Gorro — The Emperor and Horus battle together against Orks.
The Battle of Keylek — The Luna Wolves exterminate the Keylekid.
The Rangdan Xenocides — The Dark Angels lose 50,000 Battle-Brothers saving the northern Imperium from the Rangda.
"Who were the Rangdans?" Ironwood asked.
"We're not going to answer that question." Z said dismissively.
"But we're here to learn about the Imperium!" Ironwood protested.
"We must know about these Rangdans." Clover added.
"No, this information is classified." D replied.
"Why?" Harriet asked.
"Because we don't talk about them." Z replied.
"Listen here we need to-" Ironwood said.
However he was cut off when Z's microphone staff impaled the floor just in front of his feet before getting into Ironwood's face, who was now thoroughly terrified.
"We. Don't. Talk. About. Them." Z said in a tone so cold that the air coming from his mouth had fractals of ice in them.
Battle of Sixty-Three Nineteen — Horus brings the world of Sixty-Three-Nineteen into the Imperial fold.
"This battle had serious consequences for the Imperium which you will find out later." D said.
Fall of the Lords of Gardinaal — The 413rd Expeditionary Fleet and Ferrus Manus subdue the advanced human world of Gardinaal.
"Oh boy wait till we cover this when we look at Ferrus Manus." Z said, rubbing his hands together.
Battle of Gyros-Thravian — The Emperor, Rogal Dorn, Mortarion, and Horus defeat one of the most powerful Ork Warbosses in recorded history, Gharkul Blackfang.
"How strong are these Orks?" Smoker asked.
"You'll see." Z replied.
Conquest of Galaspar — The Death Guard conquers the world of Galaspar.
Cleansing of Laeran — The Emperor's Children annihilate the Laer.
Golgothan Slaughter — The World Eaters battle the Brotherhood of Ruin and Orks on Sarum.
Battle of Gate Forty-Two — Horus leads four Legions in a major assault that sees heavy Raven Guard losses.
"Something tells me this battle caused an argument." Najenda said.
"You are correct." D replied.
Ullanor Crusade — Horus defeats the empire of Ork Warboss Urlakk Urg.
Battle of 47-16 — The Word Bearers sack the world of 47-16.
Diasporex Conflict — The Iron Hands and Emperor's Children battle the Human-Xenos confederation known as the Diasporex.
War on Murder — Horus and Sanguinius battle the Megarachnids.
Interex Conflict — Horus invades the advanced human civilization Interex.
Battle of Davin's Moon — Horus unwittingly falls into a Word Bearers trap and falls to Chaos.
The audience perked up at this fact.
Auretian Technocracy War — Secretly dedicated to overthrowing the Emperor, Horus wages war on the Auretian Technocracy.
"This is ominous." Akame noted.
The End of the Crusade
The age of the Great Crusade ended with the virus bombing of Isstvan III by Warmaster Horus, which announced the beginning of his Rebellion. The loyalist legions were recalled to Terra to defend against the traitor Warmaster, but not all of the Legions were able to return. The Ultramarines were mired in the Ultramar system fighting Kor Phaeron and his retinue of Word Bearers that had come to destroy them. The Space Wolves were finishing their battle at Prospero with the now openly traitorous Thousand Sons, the White Scars were mired in the Chondax Campaign, and the Dark Angels were in the midst of a civil war on Caliban and a slow campaign against the Gordian League.
In many ways the Emperor was now gone, The Imperium suddenly finding itself without the great leadership of the Guardian of Mankind. The brief age of recovery which the Great Crusade represented was over, and mankind began to decline into the state it is now, with fear and chaos rife, Inquisitors seeking out heresy at every corner and billions of people living in forced, and willing, slavery to their God-Emperor.
That last paragraph disturbed many, seeing the Emperor's dream turn into a nightmare.
"In the grim dark future, there can be no peace." D said with a morose expression, Z nodded while clicking his tongue.
"And we're gonna see the terrible and cataclysmic event that caused this, the Horus Heresy." Z said after a moment.
"Are we going to see it next?" Ruby asked curiously.
"No, because we are going to explore and examine the military forces of the Imperium now." D said before clicking the remote.