Running from 832 to 845.M41 the Black Sun Crusade takes its name from the Black Sun of Medrengard, fortress world of Perturabo. It retrospect it seems clear that the incursion in force was the intended first blow of a new Black Crusade. Had Perturabo achieved a full warp transition of Medrengard and established himself in Aliris Sector it would have been possible for Abbaddon's forces to avoid the defenses around the Eye and drive directly for Holy Terra.