The Enslavement

After the near destruction of the Warband, the Brotherhood pledged its allegiance to Chaos in order to replenish their loses at a faster rate through the help of nearby Hellforge. Effectively, this decision ends up turning the Warband into slaves, doing the Dark Mechanicums bidding, Until war broke out between the 2 factions, the Hellforge capitulated and was forced to donate to the Astartes all gear requested by them.