Event · M30–M31
First Founding
The First Founding is the Emperor of Mankind’s creation of the twenty Space Marine Legions on Terra in the late thirtieth millennium. It marks the point at which centuries of genetic research into the Emperor’s own physiology yielded gene-seed stable enough to be implanted in selected recruits, producing the first companies of Legiones Astartes. The programme was conceived as the instrument by which Terra would reclaim humanity’s scattered colonies, and its establishment is treated in later tradition as the true beginning of the Great Crusade, preceding the recovery of the primarchs who would eventually command the Legions it raised. Recruitment drew heavily on Terra itself, supplemented in the following decades by warriors gathered as the Crusade fleets advanced, so that each Legion’s early character owed as much to its founding cadre as to the primarch later placed at its head. In this initial period the Legions answered directly to the Emperor and to the Council of Terra, fighting as unified but still primarch-less forces alongside the newly formed Legio Custodes and the Imperial Army. The reunion of each Legion with its primarch, beginning with Horus and the Luna Wolves, transformed these founding formations into the personal instruments of twenty distinct commanders, each shaping his Legion’s doctrine, culture and name in ways that endured until the Heresy. The First Founding’s legacy was decisively altered by the Horus Heresy, when half the Legions turned against Terra and the surviving loyalists were broken apart in the Second Founding that followed, replacing the old Legion structure with smaller, dispersed Chapters. Of the First Founding’s original twenty formations, only a minority persist in name and lineage into the present era, chiefly among the Loyalist Chapters still honouring their primogenitor Legion’s heraldry and doctrine, while the fate of several Traitor Legions after the Heresy is recorded with less certainty. The event remains the foundational reference point for any account of the Adeptus Astartes, anchoring the origin of Legiones Astartes to Terra and to the earliest years of the Great Crusade.
See where First Founding occurred on the galactic map during the Horus Heresy.