Astral Claws
The Astral Claws were a Space Marine chapter until the Badab War of the early 900s.M41
Its leader, Lufgt Huron ordered the Astral Claws to destroy an Imperial Investigation Fleet which had come to find out why the chapter had not sent its usual 5% tithe of gene-seed and how they had got themselves into such a huge debt in planetary tithes.
The Astral Claws were then joined by the Executioners, Lamenters and Mantis Warriors. Eventually, the weight of the Imperium crushed the rebels and Badab was liberated.
The Astral Claws are said to have left the planet during the blockade and fled to the Maelstrom where they became the Red Corsair pirates. They took the broken body of their master with them, and he is said to lead them in raids on the Imperium, although he is more machine than man now.