Crusades of the Black Templars

378.M36 - The Wars of Apostasy
When the insane High Lord of the Administratum, Goge Vandire, declared himself both Ecclesiarch and High Lord of the Administratum he began the now infamous Reign of Blood, a time of terror in which millions died in the fires of megalomaniacal paranoia. Violent repression and wanton slaughter were the hallmarks of his reign until a holy man by the name of Sebastian Thor rallied the faithful to stand against Vandire. During this time, the Black Templars had concerned themselves little with the affairs of the Imperium, but when Crusade fleets returned to Segmentum Solar and discovered that their Chapter keeps had been destroyed by orbital bombardments, the full extent of Vandire's treachery became apparent. High Marshal Sigenandus declared a Crusade against Vandire and, together with their Primogenitor Chapter, the Imperial Fists, two other Chapters - the Fire Hawks and the Soul Drinkers - and the Martian Tech Guard, the Black Templars took the fight to Terra itself.
For months the combined armies laid siege to the Ecclesiarchal Palace without success until a forlorn hope led by Emperor's Champion Navarre assaulted a breach in the outer walls. The fighting waxed fierce and when the bearer of the Chapter Banner fell, Navarre lifted it high and carried the holy icon across the breach to victory. After the battle, Chapter Master Lazerian of the Imperial Fists honoured Navarre with the title of Captain of the Banner in recognition of his exemplary bravery. With the capture of the outer walls, forces loyal to the Emperor fought within the precincts of the palace, something that had not happened since the dark days of the Horus Heresy. The siege was ended with the death of Vandire at the hands of Alicia Dominica, leader of the Brides of the Emperor, the High Lord's personal bodyguard who now learned the awful truth of Vandire's reign. With Vandire dead and Sebastian Thor appointed Ecclesiarch, Sigenandus led his warriors from Segmentum Solar to further prosecute the enemies of the Emperor. Though Vandire's death ended the Reign of Blood, the Age of Apostasy was to continue for centuries and Sigenandus spent the rest of his life hunting down those who had broken faith with the Emperor.