The Caraseis War was waged twenty five million years ago. It was between the Empire and the forces of Caraseis ('destroyer'), a Human who was determined to tear apart the Empire.
It was one of the worst conflicts in Empirian history. As part of the war, Magvierak was destroyed by the will of Caraseis as they had not picked a side in the conflict. Many defected afterwards.
The war ended when Caraseis and his most loyal decided to invade Eistanlon. Invading Eisatanlon is an extreme taboo in the Empire, and doing so made him lose much support. While he was being defeated on Eisatanlon, the Empire invaded Earth and occupied it. After the death of the Human known as Caraseis, Catasore obliterated all of Humanity and left the planet barren.