During the Battle of Isstvan III many World Eaters went completely berserk with rage and bloodlust and only left the battlefield in chains. The Techmarines of the World Eaters later made customized suits of Terminator Armour to serve as both wargear and a means of confinement. These suits were, in effect, mechanical prison cells that could be immobilized with the press of a button.
The Red Butchers were unleashed for the first time during the Dropsite Massacre. Few survived the engagement, but they nonetheless ripped through loyalist formations. Moreover, World Eaters that went completely mad in later battles could be imprisoned within recovered suits.
- 1: The Horus Heresy Book Two - Massacre, pg. 216
- 2: Forge World: World Eaters Legion Red Butchers (last accessed 4 June 2019)
- 3: The Horus Heresy Book Six - Retribution, pg. 124