Event · M30

Astranii Campaign

The Astranii Campaign was a Great Crusade operation mounted against the Astranii Machine Empire, an advanced human civilisation encountered and judged by the Imperium to be hereteks. An initial Expeditionary Fleet made contact, and its scouting vessels were subsequently destroyed in an ambush from which only the Imperial Fists captain Sigismund escaped alive. In response, a far larger invasion was authorised, drawing upon the primarchs Ferrus Manus, Rogal Dorn and Horus Lupercal, with the Mechanicum lending its support after formally declaring the Astranii beyond redemption. The three primarchs disagreed sharply over the campaign’s purpose. Ferrus Manus, aligned with his Mechanicum allies, pressed for the Astranii’s outright destruction. Rogal Dorn argued instead for compliance and assimilation into the Imperium. Horus Lupercal mediated between them and, having heard Sigismund’s account of the ambush, inclined towards Dorn’s view; Ferrus consented to cooperate only for the duration of the fighting itself. Once the fighting had ended, the unresolved dispute was settled according to Imperial custom, by a duel of champions: Sigismund faced the Iron Hands centurion Thos. Sigismund prevailed, yet Thos refused to yield. Ferrus Manus then arrived and asked Sigismund whether he would slay a fellow Space Marine over the matter; Sigismund replied that he would not do so for so trivial a cause. Ferrus appeared satisfied by this and commanded Thos to stand down. The ultimate fate of the Astranii is recorded differently across accounts. One holds that the Machine Empire was eradicated outright, its domains purged and reclaimed in the Emperor’s name; another, concerned chiefly with the duel itself, leaves their final fate unstated. The episode is said to have left lasting ill feeling between Ferrus Manus and Rogal Dorn.

See where Astranii Campaign occurred on the galactic map during the Horus Heresy.

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