The Ordon Rift Crusade was a campaign undertaken by the Red Scorpions Space Marine Chapter into the perilous Ordon Rift region deep within the interstellar wilderness of the southwestern regions of the Segmentum Tempestus in the 39th Millennium. Filled with spatial rapids, gravitic storms and other lethal phenomena, the exact circumstances of the Red Scorpions' extended voyage into this hazardous area remain unknown.
For more than 300 Terran years, the Chapter remained out of contact with the Imperium and were thought lost. The Red Scorpions have a reputation for fighting alone as often as they have fought alongside the ranks of the Imperium's other warriors, and although they have faced defeat several times, they have always returned again from the abyss to draw their blades in the Emperor's service.
After the Red Scorpions' triumphant reappearance during the Battle of the Grey Sisters against the Night Lords Traitor Legion on Oriflame, it was established that the Chapter had founded an orbital battle station named Vigil around the Feral World of Zaebus Minoris deep within the Ordon Rift as a permanent base.
Since its discovery, the Red Scorpions and a handful of high-ranking members of the Administratum have kept the exact location of the Zaebus System, and the safe routes through the treacherous passages required to reach it, a secret, thus ensuring their security and the safety of their recruiting stock.
- Imperial Armour Volume Nine - The Badab War - Part One, pp. 82-83