Sigenandus's lack of mercy ensured that whenever a crusade was called it would end with the complete destruction of its target. He was especially enraged when he learned of the destruction of his Chapter's keeps in the Segmentum Solar by High Lord Vandire's fleet. A Crusade on Terra was declared and has since become known as the Wars of Apostasy or Terran Crusade. The siege of Vandire's palace lasted for months and, together with the Chapter Master Lazerian of the Imperial Fists, Sigenandus managed to break through to reach Vandire's inner chambers.
After Vandire was executed, Sigenandus departed Terra to track down those who attempted to escape vengeance, presumably utterly destroying countless numbers of traitors across the galaxy. He finally died in 522.M36.