Emperor of Mankind - Great Crusade: The Emperor prepared extensively for the Great Crusade in the years after Unity was achieved on Terra; He created the special astro-telepath (astropath) corps to link his eventual interstellar dominion together through the use of telepathy, and engineered the creation of the Astronomican. This was a supremely powerful psychic navigational beacon powered by the Emperor's own will and psychic abilities that would allow simplified and safer interstellar travel through the Warp across far greater distances than before.Chief amongst His designs, however, was the creation of new legions of transhuman, genetically-engineered warriors, the logical extension of the gene-troopers already under his command, though they would be far superior to the gene-enhanced troops of the Imperial Army He had used during the Unification Wars.The Emperor first undertook the Primarch Project, the creation of 20 superhuman infants whose genomes had been designed using His own genetic code as the foundation, who were intended to mature into powerful generals and statesmen for His armies. The primarchs would be beings of such great mental and physical superiority that nothing merely Human could stand against them.To enhance the primarchs beyond the capabilities that even genetic-engineering allowed, however, the Emperor also drew upon the powers of the Warp he had learned at Molech to enhance His creations, imbuing them with nearly godlike levels of charisma and capability, but also unintentionally making them susceptible to corruption by the entities of the Warp.However, this plan went awry with the intervention of the Ruinous Powers, who feared that the Emperor's designs to unite and improve Humanity might succeed too well, vastly increasing the hold of order over the universe and diminishing their own strength. It is for this reason that all of Daemonkind refers to the Emperor as "the Anathema," the embodiment of the metaphysical opposition to Chaos.While accounts vary as to exactly what happened, the end of the tale is always the same; the primarchs were cast into the Warp in their gestation chambers from beneath the Himalazian (Himalaya) Mountains in the Emperor's gene-labs despite the multiple psychic wards the Emperor had laid down upon the laboratory, and thought lost.In the aftermath of these events, the Emperor conceived a new plan. Using genetic samples that had been derived from the primarchs' genomes, He created a caste of warriors who would possess some of the same superhuman qualities of the primarchs and Himself. These successors to the genetically-enhanced Human warriors of the Unification Wars-era were the Legiones Astartes, the Space Marine Legions of the First Founding.After their creation, the Emperor led the 20 Space Marine Legions, all of their Astartes originally recruited from Terran-born adolescent males, in their first missions to give them experience in war and diplomacy through the reconquest of the rest of the Sol System.The Space Marines drove alien slavers from the moons of Saturn and Jupiter and most importantly, achieved peace and the eventual integration of Imperial Terra with the ruling Mechanicum of Mars. This crucial military and political alliance, formalised in the 30th Millennium with the signing of the Treaty of Mars, provided the Emperor with much of the technological means and materiel required to extend His crusade into the stars.At the same time, the alliance formalised the creation of the Imperium of Man and established the Imperial bureaucracy on Terra, integrating the Mechanicum as one of the myriad organisations that comprised the newborn Adeptus Terra, the massive government of the Imperium, the future Priesthood of Earth.With the final abatement of the Warp Storms caused by the birth-pangs of the Chaos God Slaanesh and ended by the Fall of the Aeldari, the Emperor finally began the Great Crusade in ca. 798.M30 with the campaign remembered as the First Pacification of Luna.The Emperor's forces, concentrated amongst a rapidly growing cadre of expeditionary fleets, rediscovered long-lost Human colony worlds, cast out alien oppressors, and claimed vast new territories for the newborn Imperium to exploit across the galaxy.Perhaps most importantly, the Emperor, leading His crusade, rediscovered His lost sons, the primarchs, as the expeditionary fleets pushed out deeper into the depths of unexplored space. Scattered across the galaxy, the primarchs were found one-by-one, over a period of many solar decades, and reunited with their father and their own genetic sons in the Space Marine Legions.All were placed in command of the Astartes Legions created from their respective gene-seed and played a major part in forging their father's Imperium.Together they brought thousands of worlds into Imperial Compliance, establishing the rule of the Imperium over these worlds and inculcating in them the values of the Imperial Truth -- a materialist, atheistic faith in reason, science and technological progress that rejected all the vestiges of Human irrationality and superstition, including all forms of religious faith.Only by promulgating the doctrines of the Imperial Truth did the Emperor believe He could begin to weaken the hold of the need for faith and the other irrational aspects of the Human mind that birthed and sustained the power of Chaos in the Warp.The Emperor Himself declared that Mankind would never be free to progress and advance to its destined position as the pre-eminent intelligent species in the Milky Way Galaxy until "the last stone from the last church was cast down onto the last priest."He had already purged ancient Terra of all its ancient religions and superstitious beliefs by the time the Great Crusade began, even going so far as to personally witness the destruction of the final church on Terra's ancient soil after engaging its resident holy man, Uriah Olathaire, in a battle of ideas, wit and dogma.The Imperial Truth also held that Humanity was the species which should rightfully rule the galaxy since its physical form was both the most pure and all of the other intelligent alien races, such as the Aeldari, had already tried and failed to maintain galaxy-spanning civilisations.Now it was Humanity's turn to find a place amidst the stars. As almost all intelligent alien species encountered by Mankind had either proven to be irrevocably hostile to Humanity or presented a future threat to Human dominance and exploitation of the galaxy, xenos species were generally to be exterminated outright if they presented the slightest threat or obstacle to the Imperium.The Emperor believed the Imperial Truth needed to be brought to all the worlds of Humanity, peacefully at first but imposed by war if necessary, because the Emperor believed that true unity was the only way for Humanity to survive and prosper in the face of a very hostile universe.If this required the unfortunate use of force against those who refused to understand this necessity, then so be it. Just as He had during the Unification Wars, the Emperor again lamented the loss of innocent lives and the curtailing of individual freedoms that the fleets of the Great Crusade sometimes trod upon, but He could see no other way to safeguard Humanity and weaken the endless corruptive power of the Ruinous Powers at the same time.While the Imperial Truth upheld the light of reason and science, it did have one unbreakable proscription: Men must never develop machines capable of true thought, what scientists had once called artificial general intelligence.The Emperor remembered that it was the great war fought by Humanity against the thinking machines known as the Men of Iron that had helped to destroy Mankind's last united interstellar civilisation at the end of the Dark Age of Technology and He had no desire to see the Human race repeat its past mistakes.As such, when the expeditionary fleets of the Great Crusade encountered advanced Human civilisations in the dark of space that had developed artificial general intelligences, these worlds' populations were simply exterminated outright as potential dangers to the entire body politic of the newborn Imperium.