The 13th Founding, also known as the Dark Founding, occurred sometime between the 35th and 36th Millennium, and is one of the very rare Foundings of Space Marine Chapters that were not recorded in exact detail. Since the Horus Heresy, the Adeptus Terra has maintained a bank of original gene-seed tithed by every single Chapter ever created, with one notable exception: the 13th Founding. There are no reliable records that indicate how many Chapters were created during the Dark Founding or what became of them. Full disclosure of the exact details of this mysterious Founding may lie buried deep within the record office of the Adeptus Terra. There is only one known Chapter that was Founded at this time -- the mysterious Exorcists Chapter, though there are two suspected Chapters created during this unrecorded Founding -- the Death Spectres and the formerly-Loyalist Crimson Sabres.
The exact nature of the Exorcists' creation and the gene-seed used in their Founding has remained classified by a special Bull Absolute of the Inquisitorial Representative issued at the time of their Founding. The Chapter has long-standing and strong links with the Inquisition and certain factions within the Ordo Malleus in particular, and it is most likely that it is the sponsorship and designs of that Ordo that has given them their unique character, and may well have specified their creation, either as a grand experiment or for some singular purpose. They are unusually resistant to both daemonic possession and Chaotic corruption. As part of their initiation into the Chapter, Exorcists Astartes are forced to serve as Daemonhosts for a short time before the possessing daemon is expelled back to the Warp by the intervention of an Inquisitor.
The Death Spectres are the second known Chapter to have been created during this unusual Founding. They are a Successor Chapter of the Raven Guard and share the same mutations as found in that Chapter's gene-seed. Like the Raven Guard, the Battle-Brothers of this Chapter possess a minor mutation that causes the Melanochromic Organ (which controls the amount of melanin in an Astartes' skin tone) to not function properly, leading to the development of albinism in Death Spectres Astartes. Differing Melanochrome gene-seed from Chapter to Chapter leads to variations in skin and hair colour, and in some Chapters all of the Space Marines may have identical colouration, such as is found in the albino warriors of the Death Spectres Chapter.
Finally, there is the Crimson Sabres Chapter. The Renegade Space Marine warband who call themselves the Crimson Slaughter were once the Crimson Sabres Chapter of Space Marines. Since their betrayal and excommunication, many have sought out the Chapter's origins, delving back into their past to find perhaps some reasoning behind their rapid decline into savage butchery. Thus far, the Inquisition has failed to reveal any conclusive evidence that links them to corrupt gene-seed or known mutagenic factors. It is surmised by many, from Inquisitors to curator-scribes, that the Crimson Sabres may have belonged to the 13th Founding, but nothing has ever been proven.
Select 13th Founding Chapters
|Exorcists||Grey Knights||Unknown||Banish||The Exorcists were Founded as part of a highly-classified Imperial experiment to create Space Marines who were unusually resistant to daemonic possession and Chaotic corruption. As part of their initiation into the Chapter each Exorcists Astartes had actually been forced to serve as a daemonhost for a short time before having the foul creature expelled back to the Warp by the intervention of an Inquisitor.|
|Death Spectres||Raven Guard||Corvus Corax||Occludus||A Successor Chapter of the Raven Guard as they share many of the same mutations as found in that Chapter's gene-seed. Stationed beyond the frontiers of the Imperium, the Death Spectres maintain a constant vigil to ensure that the supernatural inhabitants of the Ghoul Stars never again threaten the galaxy.|
|Crimson Sabres (Excommunicate Traitoris)||Unknown||Unknown||Rhoghon||Their Chapter's reputation was built on ruthless efficiency and fastidious adherence to the Codex Astartes. Soon enough, signs that things were awry appeared in their Chapter history. These problems culminated with the genocidal war on Umidia. This world proved to be the fulcrum of change for the Crimson Sabres. The fighting there proved so intense that it changed the Chapter, as they found themselves cursed by the Chaos God Khorne, forever haunted by the fell voices of the slain even after the combat had ended. Fleeing into the Eye of Terror, they were eventually corrupted into full-fledged Chaos Space Marines. Renamed the Crimson Slaughter, the voices which plague them can no longer be silenced except by the most obscene levels of carnage.|
- Codex: Armageddon (3rd Edition), pg. 18
- Codex: Eye of Terror (3rd Edition), pg. 16
- Codex: Space Marines (5th Edition), pg. 26
- Codex: Ultramarines (2nd Edition), pg. 8
- Crimson Slaughter: A Codex Chaos Space Marines Supplement (6th Edition), pg. 83
- Hammer and Bolter 2, "Exhumed" (Short Story), pg. 30
- Heroes of the Space Marines (Anthology), "Headhunted" by Steve Parker, pp. 251-304
- Imperial Armour - The Badab War - Part Two, pp. 124-131
- Warhammer 40,000 Rulebook (5th Edition)
- Headhunted (Short Story) by Steve Parker