Astranii Machine Empire

The Astranii Machine Empire was a region of Segmentum Pacificus encompassing an advanced human civilisation discovered during the Great Crusade. The Mechanicum, judging its technologies heretical, declared its population heretek and marked the realm for annihilation. The scouting elements of the first Expeditionary Fleet sent to assess the domain were wiped out in an Astranii ambush, with the Imperial Fists captain Sigismund the sole survivor; a larger invasion followed, the Astranii Campaign, led jointly by the primarchs Ferrus Manus, Rogal Dorn and Horus.

Among the primarchs, Ferrus Manus and the Mechanicum pressed for the civilisation’s destruction, while Dorn argued for bringing it to compliance; Horus mediated between the two positions. The matter was resolved after the fighting through an honour duel between Sigismund and Thos, a centurion of the Iron Hands. One account holds that the Astranii were ultimately eradicated and their domains purged and reclaimed in the Emperor’s name; beyond this, little is recorded of the worlds that made up the realm.