The Imperium
First Warnings
Black Crusade
The Gathering
The Imperium
The earliest of records tell of a time known as the Age of Strife. During this time the galaxy was in a state of war and savagery, as vast warp storms made interstellar travel a nearly impossible task. Earth was reliant upon imports, without which civilization crumbled. Billions died, and millenia of technological advancement was forgotten. A barbaric society of warlords and warrior tribes emerged and continued for approximately ten thousand years, at which time the warp storms finally abated.

By that time, a mighty leader had emerged on Earth, and had succeeded in uniting the entire planet under his rule. Under his guidance, ancient technologies were rediscovered and improved. His name has been lost in time, and he is only known as what he became - the Emperor.

One of the major areas of research engaged in was that of genetic enhancement. This led to the Primarch project - the creation of super-humans with incredible strength and cunning. The embryonic pods of the genetic material were cast into the galaxy by the Dark Gods of Chaos, but not before a sample was taken from each one. These samples were cultivated into small organs that, when implanted into a human, transformed their host into a supreme warrior. Thus was borne the Space Marines. As there were twenty such Primarchs, twenty Legions were created, each exhibiting some of the unique talents of their progentior Primarch.