The Age of Apostasy was one of the darkest internal crises in Imperial history, a period of civil war and religious tyranny that nearly tore the realm apart from within. It centred on the rise of Goge Vandire, a ruthless zealot who seized control of both the Administratum and the Ecclesiarchy, uniting temporal and spiritual authority in a single pair of merciless hands.
Vandire's reign, remembered as the Reign of Blood, saw untold billions condemned as heretics and put to death on his whim. His madness and paranoia plunged countless worlds into rebellion and slaughter, while his enforcers carried out his will with fire and blade. For decades the Imperium bled itself white in purges and uprisings even as the true enemies of humanity gathered at its borders.
Deliverance came through the preacher Sebastian Thor, whose movement of the faithful rose against the tyrant, and through the fanatical warrior-women who had served as Vandire's own bodyguard until his lies were exposed. His fall brought sweeping reforms, most enduringly the decree that the Ecclesiarchy could keep no men under arms, a loophole answered by the founding of the Adepta Sororitas. For a fuller account, see the Age of Apostasy.