The Signus Campaign, also known as in some records as the Battle of Signus Prime, was a major Imperial military action conducted at the close of the Great Crusade in the early 31st Millennium by the Blood Angels Legion to cleanse the Signus Cluster — a triple star system of the Segmentum Ultima near to the galactic centre. The Primarch Sanguinius' IX Legion was ordered by the Warmaster Horus to cleanse the 7 worlds and 15 moons of the Signus Cluster of xenos invaders and release the humans settled there from their xenos-overlords. Unaware of Horus' perfidy and determination to betray the Emperor of Mankind, Sanguinius willingly obeyed his brother Primarch and immediately set out for this volatile region of space. Unbeknownst to the Blood Angels, they were blindly walking into a deadly trap