In 920.M41, the Renegade Chapter of Chaos Space Marines known as the Company of the Shadow invaded the Imperial Fortress World of Mortain. The Renegade Astartes intended to perform a great Chaotic ritual that would submerge Mortain in the ethers of the Warp, transforming it into a Daemon World where their dark master could extend his influence. These vile plans were halted by the intercession of a Grey Knights strike force led by Grand Master Vorth Mordrak and Inquisitor Kracen. The Company of Shadow and their zombified thralls were swiftly defeated, and the surviving Chaos Space Marines rode the winds of the Warp back to their night-shrouded homeworld of Bastonbeil to lick their wounds. However, the victory had scarcely been gained by the Grey Knights when a fleet of Red Corsairs, led by