Great Crusade - End of the Age of Strife: During the Age of Strife the Emperor, who had spent all the years of His immortal life since His birth in the 8th Millennium B.C. seeking to guide Mankind to a better destiny, was trapped on the techno-barbarian-ravaged Earth. This was due to the massive Warp Storms prevalent throughout the galaxy in the 5,000 standard years before the birth of the Chaos God Slaanesh once more made travel and astropathic communication through the Warp possible.Not content to simply sit back while humanity suffered through the long years of Old Night, the Emperor of Mankind spent this time performing intensive biological research on the human genome in gene-laboratories hidden deep below the Himalazian (Himalayan) Mountains, seeking a way that he could ultimately reunite all of humanity so that it could once more pursue its destiny of taking control over the Milky Way Galaxy as other intelligent species like the Eldar had already done.The Emperor, who did not bear that title at this early date, had always worked to advance His agenda from behind the scenes and a long list of different identities over the millennia, some of them very well-known. But to save Mankind from the disaster of the Age of Strife, it had become apparent that He would have to take a far more open political role than He had previously preferred if the human race was to be saved from ultimate extinction.The result of His scientific work was the creation of the first prototype supersoldiers who would serve as a template for the later development of the Space Marines. Using these first genetically-engineered supersoldiers called the Thunder Warriors, the Emperor unleashed the Unification Wars upon the techno-barbarian tribes and nation-states of Terra, forcing them to unite under a single government represented by a banner called the Raptor Imperialis with Himself taking the title of the "Emperor of Mankind" after years of savage warfare. This event was later known in Imperial records as the Unification.After this, the Emperor realised that to reunite all of humanity, He would need generals and proconsuls in addition to Himself whom He could trust absolutely and who possessed capabilities similar to His own. So he ordered the creation of 20 highly advanced, genetically-engineered transhumans known as the Primarchs. These men, created using the Emperor's own genome as the foundations of their genetic code, were intended to lead the reunification of Mankind.The Ruinous Powers of Chaos, however, fearful of the affect the Emperor's plans would have upon their own power within the Immaterium since they were dependent upon mortals for their very existence, managed to bypass the arcane wards protecting the Emperor's secret gene-laboratory under the Himalazian mountains, and teleport the unborn Primarchs, still in their gestation capsules, away from Terra. They were scattered across the galaxy to different human-settled worlds and several were tainted with the touch of Chaos that would bloom in time.Facing this setback, the Emperor decided to change His tactics if not His ultimate goal of reunification. He gathered the remaining genetic material that had been used to create the Primarchs and from it cultured thousands of sets of gene-seed. These could be gestated into individual sets of 19 separate organs that when implanted within the body of an adolescent human male would transform him into one of the transhuman warriors known as the Astartes in High Gothic, the first true Space Marines.The Emperor raised 20 Legions of Astartes, each making use of gene-seed organs cultured from the DNA of one of the Primarchs, from among the population of a newly unified Terra. After five millennia and the birth of Slaanesh following the events that led to the Fall of the Eldar, the massive Warp Storms finally dissipated across the galaxy. With their absence allowing interstellar travel once again, the Emperor quickly moved forward with his plans to begin the conquest of the galaxy.