The Sanguinor, Exemplar of the Host, is a mysterious entity of unknown origin that is associated with the Blood Angels Space Marines Chapter, and has been named after Sanguinius, the Blood Angels' martyred Primarch. Not much is known about his origins, and what information does exist is really nothing more than speculation by the Chapter's Librarium and several Imperial scholars well-versed in the lore of the Adeptus Astartes. The Sanguinor often appears during the Blood Angels' periods of greatest need, usually during a combat situation. To many among the Battle-Brothers of the Chapter he is no more than a myth, as few ever survive the battles where he has manifested, but the initiates of the Blood Angels' Reclusiam know differently, having kept detailed records of his manifestations down through the centuries. While the Sanguinor's deeds are unquestioned, there has always been much debate concerning his origin and identity. The members of the Blood Angels' Chapter Council argue that the Sanguinor is the manifestation of Sanguinius' own better nature, lost to the Chapter with his death at the hands of Horus aboard the Warmaster's Battle Barge during the climax of the Battle of Terra. The Sanguinary Guard do not believe that the Sanguinor is the Chapter's Primarch but that he is Azkaellon, the original founder of the Sanguinary Guard, who has been preserved beyond time by the divine will of the Emperor. The Inquisition's savants have their own opinions about the matter, theorizing that the Sanguinor is some sort of psychic construct born of the Warp through the collective desires and needs of Blood Angels Space Marines when groups of them are under extreme duress. This only further supports the beliefs of some members of the Inquisition that the Blood Angels as a Chapter have come perilously close to mutation, corruption and ultimately heresy. Whatever the reality of the matter, the Sanguinor is an honoured part of the heritage of the Blood Angels Chapter, as integral to their identities as servants of the Emperor of Mankind as the rest of their traditions and rituals.
None know from where the Sanguinor comes, yet there are two credible possibilities. The first is that the Sanguinor is the last member of the Blood Angels' Sanguinary Guard to have survived the Horus Heresy, Azkaellon, although this seems implausible, even with the long life-spans granted to Space Marines by their genetic alterations. The second, and more widely accepted, possibility is that when the Primarch Sanguinius was slain by Horus, his soul split in two: that half which was full of anguish, pain and doubt over his actions during the Horus Heresy became the Flaws that torture the Blood Angels to this day, while that part which was noble and righteous formed into the Sanguinor within the Immaterium. However the Sanguinor came into existence, the Blood Angels of the present day always see his coming as a harbinger of hope and the Emperor's divine will.
The Sanguinor rarely appears on the field of battle, only arriving when the Blood Angels are in dire need of his aid. The Sanguinor will not simply use his power to provide an instant victory, but he will aid the Blood Angels in carrying out combat tasks that without his aid would simply have been impossible to achieve. Over the millennia, the records of his appearances illustrate that he has never provided his aid to the Chapter lightly, and will not appear just because some Blood Angels face difficulties in combat. The situation must be both dire and of great import to both the Chapter and the Imperium itself before the Sanguinor will manifest.
The Khartas Incident
During a battle between the Blood Angels and Ork pirates on the planet Khartas, the crashed Ork flagship's Warp-Drive malfunctioned, opening a Warp-gate into the Immaterium, out of which countless daemons poured, including the lord of the Bloodthirsters: Ka'Bandha, the daemon who had once bested Sanguinius himself. This Greater Daemon of Khorne faced only 30 Space Marines and the Captain of the Blood Angels' 4th Company. In a duel, Ka'Bandha quickly killed the officer, and his hordes of Khornate Lesser Daemons proceeded to attack the remaining Astartes. Ka'Bandha spread his massive bat-like wings wide and attacked the strongest point of the Marines' defence: five Tactical Space Marines holed up in a ruined cathedral dedicated to the Emperor. It was then that, like the divine hand of the Emperor himself, the Sanguinor, appearing from nowhere, struck Ka'Bandha out of the skies. Then followed a great duel between the angel and the daemon, in which neither could gain the upper hand, though the Sanguinor broke the infernal beast's potent Khornate battleaxe. Then the Sanguinor stabbed the daemon with his sword, and used his jump pack to rise high into the sky, taking the daemon with him. When the Sanguinor had reached the apogee of his flight many thousands of metres above the surface of Khartas, he released the impotently flailing daemon, which hurtled to the ground and dug a crater into the ground filled with daemonic gore even as Ka'Bandha's spirit was banished to the Warp for 1,000 standard years. Shortly afterwards, the remaining Space Marines destroyed the Orks' malfunctioning Warp-Drive, and slew the remaining daemons of Khorne. When the Blood Angels' Stormravens finally arrived at Khartas to recover the surviving Astartes after receiving their distress signal, only six Battle-Brothers had survived, and the Sanguinor had vanished from wherever he had come.
- Codex: Blood Angels (5th Edition), pp. 51, 66, 82