The Nova Terra Interregnum

In the long dark centuries after the Age of Apostasy, the Imperium suffered a division that nearly sundered it forever. The Nova Terra Interregnum, also called the Age of Redemption, began when the ruling council of the Segmentum Pacificus renounced the authority of the High Lords of Terra and declared their own dominion from the world of Nova Terra.

The schism was as much spiritual as political. The Ur-Council styled themselves the true guardians of the Imperial Creed, and vast swathes of the galaxy's western reaches heeded their call, breaking away from the rule of Holy Terra. For nearly two thousand years the Imperium of Man existed as two rival realms, each claiming legitimacy, each condemning the other as heretic and pretender. The forces of the Astra Militarum and the fleets of countless worlds were drawn into the long, grinding struggle between the two factions.

Unlike the sudden fury of the Horus Heresy, the Interregnum was a slow bleeding, a wound that would not close. It was ended at last not by decisive battle but by the gradual reassertion of Terran authority, the rival council eventually brought back into the fold. Yet the memory of a divided Imperium lingered as a warning, proof that the greatest threat to mankind's realm had always been, and would always be, itself.