Event · M35
Twelfth Founding
The Twelfth Founding is a stage in the Imperium’s sequence of Space Marine Foundings, the periodic creation of Chapters under the Codex Astartes. Following Roboute Guilliman’s Second Founding, which divided the loyalist Space Marine Legions into a thousand Chapters after the Horus Heresy, the Imperium continued to sanction further Foundings across the succeeding millennia to offset losses and extend its military reach. Terra, as the seat of the Adeptus Terra and the administrative heart of the Imperium, remains the point from which such Foundings are authorised, tying the Twelfth Founding to the wider Imperial chronology anchored at the Throneworld. Each Founding draws on preserved gene-seed stocks, assigns a Chapter Master, and allots a home world or fleet basis before a new Chapter is formally recognised by the Adeptus Astartes and the High Lords. The Twelfth Founding falls among the numbered Foundings whose full roster of resulting Chapters is not uniformly preserved in surviving Imperial records; accounts differ on which Chapters trace their origin to this specific Founding, in contrast to the more thoroughly documented Second Founding and the notorious Twenty-First, or ‘Cursed’, Founding of the thirty-second millennium. What is consistently recorded is its place in sequence, situated between the Imperium’s earliest post-Heresy reorganisation and the later Foundings that would eventually draw on flawed or diminished gene-seed lines. As with other lesser-documented Foundings, the Chapters attributed to the Twelfth Founding, where their lineage is remembered at all, have long since dispersed into the Imperium’s wider order of battle, serving alongside older First and Second Founding Chapters on campaigns across the galaxy. The Founding itself endures chiefly as a marker in Astartes genealogical record-keeping, cited by Chapter serfs and Adeptus Terra archivists tracing a Chapter’s descent back toward the Second Founding and, ultimately, to Guilliman’s original Codex reforms. Its significance today lies less in specific deeds than in its place within the timeline of Astartes expansion, a lineage anchor point for Chapters whose fuller histories remain, in many cases, unrecorded.
See where Twelfth Founding occurred on the galactic map in the 41st Millennium.