The Steel Brethren, also known as the Steel Brotherhood, are a warband of Chaos Space Marines drawn from the Iron Warriors Traitor Legion. Following their parent legion's path, they are dedicated to Chaos Undivided. They have been noted to make extensive use of gunship transports and Drop Pods in their planetary assaults. The Steel Brethren, like all warbands of the Iron Warriors, possess extraordinary skill and experience in siege warfare. The Steel Brethren, when away from the Iron Warriors' Daemon World of Medrengard, operate from the Chaos Cruiser identified as the Ferrum Invictus.