Event · M35
Tenth Founding
The Tenth Founding is one of the numbered Foundings by which the Adeptus Astartes raised new Space Marine Chapters under the authority of the Adeptus Terra. It belongs to the long sequence of Foundings that began with the Second Founding’s division of the original Legions into smaller Chapters after the Horus Heresy, and continued at irregular intervals as the Imperium sought to replenish its Chapter Approved strength. Authority for each Founding rested with the High Lords of Terra and the Adeptus Astartes hierarchy seated on Terra itself, which vetted the stable gene-seed tithes and campaign needs that justified raising wholly new Chapters rather than merely reinforcing existing ones. Later Imperial chronology places the Tenth Founding within the thirty-fifth millennium, though, as with several of the numbered Foundings from this era, surviving Administratum records are fragmentary and accounts differ on its precise year and full roster of Chapters. Its course followed the pattern typical of such events: candidate gene-seed stocks were assessed for genetic stability, favoured Chapters and Forge Worlds were called upon to provide the raw material, and newly formed Chapters were assigned Chapter Masters, home worlds, and sectors of responsibility before being dispatched to active fronts. The Founding is remembered less for a single battle than for the institutional act of expansion itself, undertaken amid the Imperium’s continual need to answer attrition among the Adeptus Astartes with fresh strength. Chapters attributed to the Tenth Founding took their place among the wider brotherhood of the Adeptus Astartes, serving alongside Chapters raised in earlier and later Foundings and answering to the same Codex Astartes traditions where their progenitor Chapters observed it. As with much of this period’s founding history, the identities of individual Tenth Founding Chapters and their subsequent fates are not consistently recorded, and later Imperial scholars have sometimes disputed which Chapters truly originate from this wave rather than from Foundings before or after it. The event nonetheless marks a fixed point in the broader chronicle of Astartes expansion administered from Terra, linking the Founding to the parent Legions and Chapters that supplied its gene-seed and to the sectors its new Chapters were sent to defend.
See where Tenth Founding occurred on the galactic map in the 41st Millennium.