Varus Castamon
Varus Castamon is a Lieutenant in the Ultramarines Chapter's First Company. He was the commander of the Imperial forces defending Regium, which is a cornerstone of the Sanctus Line.[1a]
History
A decorated veteran, Castamon is famed for his intellect, rationality, diligence and savagery in battle. He would use these abilities after he was given command of an Imperial strike force, that was charged with turning Regium into a fortified and secured world of the Sanctus Line[1a]. This led the strike force to then execute the world's corrupt Planetary Governor[1b], shatter the separatist movement threatening the world[1a] and also forcibly convert the worshipers of the goddess Aureus Nahor into the Imperial Creed[1b]. All this was done, while Castamon also led the forces under his command with the same rationality and diligence he applied to every situation. He also studied the histories of the various high ranking officers serving him and learned how to manage their personalities, as well as the allegiances and rivalries they had made with each other.[1a]
This allowed Castamon to forge Regium into an important part of the Sanctus Line and also defeat a heretic fleet that attempted to conquer the world, in order to forge a path towards the Segmentum Solar. However sometime afterwards, during the Fourth Tyrannic War, the remnants of a Tyranid Leviathan Splinter Fleet, entered Regium's System and in doing so began casting the Shadow in the Warp. This wreaked havoc across Regium, as some of its population began rioting and the defeated separatists began attacking again. Castamon knew the true threat was the Splinter Fleet though and once it was destroyed its Shadow would disappear as well. But he would need to end the Xenos' threat before the fleet could renew itself by gorging on Regium's neighboring worlds. He initially planned to personally lead his warfleet against the Tyranids, with the entirety of his Ultramarines as part of the attack, but Regium's new Planetary Governor, Seroc, objected to this. The Governor explained that since Regium's safety was paramount to the integrity of the Sanctus Line, Castamon could not leave it unattended nor without the protection of the Ultramarines. Castamon agreed with this and he instead gave the command of the attack to his Battle Brother, Lieutenant Tyrus. While most of the Ultramarines would join Tyrus, the small remainder would remain on Regium under Castamon's command.[1a]
Amongst them was Sergeant Tanaro and the Librarian Zuthis Abarim, who was a friend of Castamon. After Tyrus had led his warfleet to hunt the Tyranids, though the Librarian privately vented to the Lieutenant about his battle plan. Abarim felt sure that the mortal troops under Castamon's command would not be up to the task of defending Regium from its rioting population and the separatists' attacks. He also felt that Seroc was not strong enough to serve as the world's Planetary Governor in this trying time. Castamon disagreed though and tried to assure the Librarian that he was mistaken in his beliefs. However not matter what the Lieutenant said, Abarim was not left assured by his friends' words.[1a]
Ultimately, the Ultramarines were unable to prevent the Tyranids from overrunning the defenses of Regium. Still determined to prevent Tyranid victory, Castamon and the rest of his squad sought to destroy the entire planet to deny the Xenos biomass. Apothecary Vultis concluded that the world could be destroyed by overloading the plasma reactor cores of its geoengines.[1c] As they plunged beneath Regium's surface to react the reactor core, they were pursued by a Norn Emissary and Castamon was gravely wounded but survived by putting himself in a self-induced catatonic state for recovery.[1d] In the end, the Veteran Baraca plunged both himself and the Norm Emissary into the plasma core, causing a chain reaction that resulted in Regium's destruction along with much of the Tyranid host.[1d]
Vultis was able to survive the destruction of Regium with the still-catatonic Castamon and a number of civilians.[1e]
