Imperium of Man - Great Crusade, M30-M31: Legend tells how at the end of the Age of Strife the Human homeworld writhed in the grip of terrible wars beyond count before the Emperor came. Techno-barbarians battled collectives of gene-soldiers through the blazing ruins of once-great arcologies. Cannibal savages unleashed unholy psychic powers upon legions of cyborg zealots.Grand warlords, demagogues and psyker proto-deities rose and fell, each one threatening to finally take the planet and its people with them into damnation.Yet the man who would become known as the Emperor sensed that the Warp Storms that had marked the Age of Strife were starting to subside, and that this offered an opportunity for Humanity to reunite in pursuit of a new Golden Age. The Emperor first emerged from His secret fortress beneath the Himalazian (Himalayan) Mountains in the late 29th Millennium.He sought to unify all the techno-barbarian states of ancient Terra under His rule through either diplomacy or the waging of the brutal military campaigns later called the Unification Wars against the techno-barbarians tribes that ruled vast swathes of the Earth's blighted surface.These wars were waged with superhuman soldiers later known as the Thunder Warriors who had been genetically-engineered by the Emperor's genius from his early followers to be faster and stronger than base-line Humans. Such warriors would provide the early foundation from which He would later decide to create the Space Marines.After conquering the last of the independent techno-barbarian states of Old Earth, the Emperor began to lay the foundations of His burgeoning Imperium. At last, the Age of Strife was over. Hope was restored. Yet hope has ever been Humanity's addiction and curse both...Understanding that no one man, even one such as He, could rule alone, the Emperor formed His War Council, comprised of His most able generals and a number of high-ranking administrators, the most formidable of whom was Malcador the Sigillite.Malcador was not a warrior, but a man of learning with the bearing of a priest. His origins were unknown to all save perhaps the Emperor Himself, to whom some believed Malcador was distantly related.Malcador was appointed to administer the newly-constructed Imperial Palace and Court in the Himalazian Mountains, and through this appointment also governed newly conquered Terra as his master's left hand. Where Terra had been a place of unending war it now became a place of unceasing activity, production and planning.Just as the conquest of Old Earth was complete a mighty and unforeseen cosmic event occurred. A massive shock wave blasted across the Immaterium, clearing the Warp Storms that had plunged the galaxy into tumult and raged for more than five thousand standard years.It seemed to some to be divine providence, fuelling the beliefs of those that considered the Emperor to be Himself divine (no matter how much He decried this claim). The way to the galaxy was now open and the Emperor's armies would be able to take to the stars, with the other planets of Terra's solar system the first step upon that road.After conquering the last of the independent techno-barbarian states of the renamed world of Terra, the Emperor secured the allegiance of the techno-mystic Cult Mechanicus of Mars who controlled the most advanced remaining industrial fabrication and scientific research facilities in the Human-settled galaxy.The Emperor promised in the Treaty of Mars to protect the Tech-priests' religion and respect the sovereignty of the Mechanicum and the autonomy of their Forge Worlds across the galaxy, affording them a level of independence unequalled within the Imperium. Furthermore the Emperor gave to the service of the Mechanicum six of the Houses of Navigators, so that their ships might once again travel safely through the Warp after the loss of their own thrall-Navigators centuries before.The powerful Fabricator-General of Mars was given a seat on the War Council of the Great Crusade. With access to the giant manufactoria of Mars, this enabled the Emperor to vastly increase the power of his Legions with improved wargear and supply.In addition, the Tech-priests of Mars lent their arts to the construction of the massive Warp-capable Battleships that could transport the Emperor's Legions across the galaxy, and provided the mighty city-crushing war machines known as the Titans to the ever-expanding Imperial military.The Treaty of Mars married the Terran military might of the Emperor with the industrial strength of Mars and the Mechanicum. Now possessed of the needed manpower and materiel to make His dream a reality, the Emperor mobilised the resources of Terra and Mars to launch a vast new military campaign intended to reunite the whole of Mankind, dispersed across the galaxy, under His rule.This campaign, the Great Crusade, marked the founding era of the period that would later be known as the Age of the Imperium. A vast fleet of starships was built in orbit of Mars, with which the Emperor's armies set out to reconquer the galaxy for Mankind.But even before He had begun His campaign to reunite Old Earth, the Emperor had used His highly advanced knowledge of genetic engineering and the psychic arts to create the primarchs, 20 superhuman military commanders possessed of preternatural physical, mental and social attributes who had been created through the fusion of variations of His own genetic material with the power of the Warp.The Emperor had known that the greatest foe of His plans to reunite Humanity and bring order to the galaxy would be the Ruinous Powers of Chaos and their daemonic servants. He had sought to protect His gestating primarchs from the Dark Gods while they grew in their gestation capsules in the Emperor's secret laboratories deep beneath the Himalazian Mountains, but the Chaos Gods saw through all His wards and protections.They opened a Warp portal in the Emperor's own laboratory and stole the infant primarchs away from Terra, scattering them across the galaxy and tainting many of them with the power of Chaos.Undeterred by this tragedy, the Emperor utilised what remained of the primarchs' genetic material. He had first crafted the Thunder Warriors to unite Old Earth. He then proceeded in the last days of the Unification Wars to transform ordinary Terran men into a new corps of transhuman warriors who would lead Mankind back out into the stellar void.These men were the Emperor's Space Marines, the Legiones Astartes, superhuman warriors who knew no fear. Thanks to influxes of technology and resources from around the Sol System the Space Marine Legions were soon growing in numbers and capability at an exponential rate. The Space Marine Legions were to be the spearhead of the Emperor's attempt to reunite Mankind -- the Great Crusade's killing edge against which the strength of a foe would be broken and which would topple empires, Human or alien, by ripping out their hearts.With Mars now part of the Imperium, the Great Crusade began in earnest and the rest of the Sol System was the first region of space to be conquered by the Emperor and His newly rearmed and re-equipped Space Marine Legions. The Legiones Astartes secured the scientific research installations and spacedocks of Luna which had once been controlled by the Selenar gene-wrights.Broken and humbled, the enslaved gene-wrights of Luna would help forge the next generation of Space Marines who would carry out Mankind's conquest of the stars. Alien invaders were flushed from the moons of Saturn and Jupiter and their wretched enslaved Human inhabitants repatriated to Earth, the once-Human creatures of the Neptunian Deeps were exterminated without mercy, and the baleful false-world of Sedna at Sol's edge-light was boiled away to vapour under the guns of the new-forged Imperial war fleet. The next step was beyond.The Great Crusade was a mammoth operation on an inconceivable scale and complexity that involved billions of troops and tens of thousands of voidships, and it is perhaps true that only a mind such as the Emperor's could have had a hope of successfully comprehending and executing it.In order to manifest this conquest the Imperium's forces were divided up into an expanding and frequently reconfigured series of Imperial expeditionary fleets -- semi-autonomous battle groups assigned to voyage the stars and make war in the Emperor's name.They were composed in chief of a bewildering array of voidships great and small. The paths of these fleets were dictated both in general by the Emperor and His War Council, but also by the will of their commanders who were entrusted to seek out the enslaved and destroy the alien under their own sway.During the 200 standard years that the Great Crusade spread the Imperium across the galaxy, the Emperor slowly made contact once more with all of His scattered gene-sons, the primarchs, and to each He gave command of the Space Marine Legion that had been created from that primarch's genome.Horus was the first of the primarchs to be rediscovered, on the barren Mining World of Cthonia only a few light years from Terra itself. Horus campaigned with the Emperor for 30 Terran years before the next of the primarchs was recovered, and during that time the two developed a special bond, the deep affection between a father and His favoured son.The Astartes Legions, combined with the might of the Imperial Army (which was later separated into the Astra Militarum and the Imperial Navy after the Horus Heresy), reunited thousands upon thousands of Human-settled worlds into one interstellar civilisation, in the name, and under the rule of, the Emperor and the Imperium of Man.But the Great Crusade was ended abruptly by the corruption and treachery of the Imperial Warmaster Horus, who was both the primarch of the Sons of Horus Legion and the overall military commander of the Great Crusade in its last days. This was an honour that had been granted to him by the Emperor, who had sought to leave the campaign so that He might return to Terra and oversee a highly-secret project intended to open up the Aeldari Webway to Human use.But Horus and many of the other primarchs deeply resented the Emperor's absence from the Great Crusade and were even more disturbed by His attempts to replace the direct rule of the Imperium by the Emperor and His Primarchs with a bureaucracy of normal Humans.Having established the Council of Terra, the new governing body of the Imperium to carry out the day-to-day work of ruling tens of thousands of worlds and trillions of Human beings, the Emperor took refuge in His vast laboratories and workshops beneath the Imperial Palace.He began work in earnest on his new project to secretly extend the Webway to Terra, an enterprise that the Emperor hoped would be His greatest gift to Humanity. While the Emperor was locked away in His subterranean factories, trouble was brewing.The formation of the Council of Terra proved to be a contentious decision with the distant primarchs, who were appalled when news of the formation of the council finally reached them on the frontiers of the Great Crusade. Some of the primarchs took great exception to being ruled by those mortals that they deemed less worthy and capable of such an honour than themselves.The less stable primarchs felt that this was a betrayal of all they had fought and won in the Emperor's name and that their victories now counted for nothing. They, and many of their Astartes, felt that it was they who had suffered and sacrificed the most to build the Imperium and thus it was they who should have the greatest say in how it was ruled, not a council composed of effete Terran nobles and faceless mortal bureaucrats. This was one of many growing resentments that allowed the Ruinous Powers to infect and corrupt several of the Primarchs.Riven by jealousy and ambition, Horus proved to be easy prey for the temptations of the Chaos Gods and the machinations of his own brother Lorgar, the primarch of the Word Bearers Legion, who had come into the secret service of Chaos during the course of the Great Crusade.Given the opportunity, the Dark Gods falsely convinced the arrogant Warmaster that the Emperor had intended all along to simply use the primarchs and the rest of Humanity to transform Himself into a god. Enraged and offended at this notion, the Ruinous Powers then promised Horus their support in his bid to seize the Imperium for himself.Horus ultimately convinced 9 other primarchs and their Space Marine Legions to join his cause and serve the designs of Chaos. He instigated the terrible Horus Heresy -- a galaxy-wide rebellion against the Emperor -- and eventually one-half of the Imperium's vast military forces, as well as elements of the Mechanicum, rallied to the Traitors' cause, unleashing the greatest conflict Mankind had ever known upon an unsuspecting galaxy.