Nomus Rhy'tan - The Horus Heresy: As news reached Nocturne of the Warmaster's betrayal and treachery at Istvaan III, Vulkan mobilized his Legion for a counterattack, but before departing for Istvaan V, the Primarch bade the Lord Chaplain to remain behind at Prometheus with the Legion's Neophytes and instructors as regent in his stead. With a heavy heart Rhy'tan obeyed, for he would not have abandoned his friend and Primarch so easily, but in doing so, Vulkan had destined Rhy'tan to survive, the future of his Legion in his hands.It is likely that in the first few solar weeks of his new position as Regent, Rhy'tan carried out his Primarch's orders to the letter, supervising the initiation and training of the Legion's Neophytes in matters of war and those of the Promethean Cult. Only when the dire news of the Drop Site Massacre reached Nocturne did matters changed.With very little information available as to the true fate of the Legion and their Primarch, Nomus Rhy'tan found himself in command of a Legion that had virtually been annihilated. Despite having ships and men at his disposal, Rhy'tan did not sally forth to aid or search for his Legion's Primarch, but chose to remain on Nocturne. Neither the news of Vulkan's unknown fate nor the rallying-cry from Rogal Dorn on distant Terra reached the Lord Chaplain.This did not mean that Rhy'tan sat idly. The Lord Chaplain assumed that it was only a matter of time before Nocturne would eventually come under attack during the galactic civil war that had now erupted. Rhy'tan began to fortify his homeworld by establishing a series of bastions on key strategic areas of Nocturne. The Legion's forges would work night and day to craft the necessary tools of wars to equip the Neophytes whose training regime was stepped-up accordingly.Many solar months after the events on Istvaan V, a Salamanders' Battle-Barge emerged from the Warp in close proximity to Nocturne -- the Charybdis -- which had transported Vulkan's body from distant Macragge back to his homeworld. When vessels of the Death Guard and Word Bearers appeared close behind, it was clear that Nocturne was under attack.The Lord Chaplain immediately mobilised his meagre forces and personally joined his Firedrake-bodyguard in an awaiting gunship. Observing the orbital battle between the Charybdis above Nocturne, Rhy'tan's gunship later located a downed Salamanders gunship. The Lord Chaplain soon realized that some of his surviving Battle-Brothers had returned to Nocturne and directed his own flight of three gunships to the crash zone.They arrived in time to save the still-unidentified survivors from the guns of a circling Fire Raptor gunship of the Death Guard Legion. As the Vox crackled into life, the Lord Chaplain learned that he had just saved the lives of First Captain Artellus Numeon and that of the Primarch himself!His joy quickly turned to ash upon learning of Vulkan's true condition. Despite Nocturne's isolation, rumours of the Primarch's death had reached them, although Rhy'tan would not allow hope to dictate his actions as it had for Numeon. Time would be made for talk and hope or grief, once the Death Guard had been defeated, for war had finally come to Nocturne and the Salamanders were ready to defend it.