Ortan Cassius - Deathwatch Service: Chaplain Cassius is exceptional even amongst the ranks of the Ultramarines. After learning many horrible truths about the nature of the xenos menace during his tenure in the Deathwatch Chapter, he was discharged with full honours. The Chaplain returned to the Ultramarines Chapter, bringing back the secrets he had uncovered over the course of his Long Vigil.While still only a Chaplain, it was Ortan Cassius that led an Aquila Kill-team -- Kill-team Cassius -- to Ghosar Quintus in ca. 681.M41 after the suspicious disappearance of Inquisitor Chaegryn, uncovering the Genestealer Cult known as the Cult of the Four-Armed Emperor that secretly festered beneath the Mining World's surface. This was the first Imperial encounter with the existence of Genestealer Cults and it was Kill-team Cassius which learned the truth of exactly how far the cults' corruption had spread thoughout the Human-settled galaxy. Since that fell discovery he has made it a personal crusade to prove the spirituality of Mankind superior to the perversion of religion that erupts before a Tyranid invasion.In 745.M41 Hive Fleet Behemoth made the Tyranids' first contact with humanity when its massive swarms assaulted the Eastern Fringe of the Imperium of Man, and made rapid progress towards the heavily populated Realm of Ultramar. This conflict would come to be known as the First Tyrannic War. Upon learning of the threat posed by the monstrous xenos, the Ultramarines' Chapter Master Marneus Calgar (always "young Calgar" to Cassius) drew up plans to defend his Chapter's realm. Deeming Macragge as the star system most vulnerable to the Tyranid menace, Calgar ordered the already formidable defences of Macragge to be further improved.Calgar declared that the Hive Fleet would be halted at Macragge before it consumed more of Ultramar or drove deeper into the heart of the Imperium. Only scant weeks later, the outrider vessels of the Tyranid Hive Fleet attacked the Ultramarines' homeworld and unleashed the infamous Battle of Macragge. The Hive Fleet was defeated after the Emperor-class Battleship Dominus Astra intentionally detonated its Warp-Drive, creating a Warp vortex that destroyed the majority of the Hive Fleet. Calgar's surviving starships then came about and roared back to Macragge to try to save the Chapter's beleaguered polar garrisons.Chaplain Cassius led the attempt to rescue the doomed 1st Company at the northern polar fortress of Macragge. Few of Cassius' companions emerged unscathed from the terrible close quarters fighting. Only at a great cost in life did the Ultramarines hunt down the Tyranid invaders and exterminate them, though their victory proved pyrrhic at best. Cassius himself was laid low by a rampaging Carnifex, his life sustained only by his own formidable strength of will.After a long convalescence, the Chapter's Apothecaries rebuilt the Chaplain's shattered body with extensive cybernetics, eventually enabling Cassius to return to his duties. Filled with new fire and purpose, the ancient Chaplain felt that he had been blessed with a revelation as he lay dying.He came to believe that the Tyranids' assault represented a rightful punishment for Mankind's lack of vigilance, and in Cassius' eyes there was no greater calling than to purge the vile xenos from the galaxy. To this end, Cassius forged a new force, chosen from the survivors of the Tyrannic Wars, to specialise in hunting down and destroying the Tyranid menace.Though initially few in number, each fresh clash with the Hive Fleets provides new followers to his cause. As the movement has grown, Cassius has become more focused, and his followers an ever more influential faction within the Chapter.