Event · M36–M37
Eighteenth Founding
The Eighteenth Founding is one of the numbered Foundings by which the Adeptus Astartes was replenished, dated by Imperial record to the thirty-sixth millennium. Like every Founding after the first, it was authorised from Terra, where the Adeptus Astartes’ recruiting rolls and gene-seed stocks are held under the oversight of the High Lords, and it stands in sequence between the reorganisation of the Legions into Chapters under the Second Founding and the later, better-attested Foundings of the thirty-seventh millennium and beyond. In common with other post-Heresy Foundings, the Eighteenth drew on proven gene-seed lines to raise new Chapters to the thousand-strong Codex Astartes pattern, dispatching them to garrison or reinforce sectors the Imperium judged undermanned in that era. Imperial record-keeping of this period is uneven, and the surviving accounts do not distinguish the Eighteenth Founding’s creations as sharply as they do those of more infamous cycles, such as the so-called Cursed Founding associated with later, flawed gene-seed lines. What is recorded places the Founding firmly within the broader pattern of Chapter creation that sustained the Astartes through the middle millennia of the Imperium’s history, rather than attaching it to any single named campaign. In the present era the Eighteenth Founding survives chiefly as a chronological marker rather than a body of distinct lore: few Chapters now active trace their origin to it by name in accounts available outside specialist Administratum archives. Its significance lies in its place within the continuous sequence of Foundings issuing from Terra, linking the Second Founding’s reorganisation of the Adeptus Astartes to the later, more thoroughly documented Foundings that followed it.
See where Eighteenth Founding occurred on the galactic map in the 41st Millennium.