Event · M41–M42
Rift War
The Rift War is the name given to the fighting that engulfed the Imperium Nihilus after the Great Rift split the galaxy in 111.M42. The Cicatrix Maledictum’s opening severed Segmentum Solar’s authority from its northern dominions, threw astropathic communication into ruin, and drew fresh incursions from Chaos warbands, ork raiders, and roused necron dynasties against worlds already isolated from Terra. Among its principal theatres were the fortress world of Vigilus, whose strategic position made it a magnet for rival powers, and the Nachmund Gauntlet, one of the few navigable corridors through the Rift itself. Fighting on Vigilus unfolded across successive campaigns in which Imperial defenders, Chaos raiders serving the Rift’s masters, and opportunist ork and genestealer forces contested the world’s hives and orbital approaches, each seeking to deny the others a foothold so near the breach. Further afield, control of the Nachmund Gauntlet became a recurring flashpoint, as Imperial battlefleets and Space Marine Chapters fought to keep the corridor open for reinforcements and relics passing between the Imperium’s two halves, while Chaos and xenos forces sought to seal or seize it. The war had no single climactic battle; it persisted instead as a chain of engagements across the Era Indomitus, bound to the wider effort, led in part by Roboute Guilliman’s Indomitus Crusade, to restore contact between Imperium Sanctus and Imperium Nihilus. In the current era the Rift War remains unresolved: the Great Rift endures, Vigilus stays contested ground, and the Nachmund Gauntlet continues to change hands as fortunes shift. Its significance lies less in any final verdict than in what it reveals about the post-Rift Imperium, an institution compelled to fight on two fronts across a fractured galaxy while still projecting strength through crusading hosts. The Rift War thus stands as a defining condition of the Era Indomitus, binding the fates of Vigilus, the Nachmund Gauntlet, and the wider Imperium Nihilus to the still-open wound at the galaxy’s heart.
See where Rift War occurred on the galactic map in the 41st Millennium.