Brotherhood of the Knife

The Brotherhood of the Knife is a Chaos Cult that was raised by and supported the Word Bearers Traitor Legion and is still used to provide support for the Heretic Astartes' military operations in the Long War against the Imperium of Man.

The brotherhood's was called Ushmetar Kaul in the ancient tongue of the Word Bearers' homeworld of Colchis, which translated literally into Low Gothic as "sharp edge by which false reality may be slit and pulled away to reveal god."

Its cultists wore long robes, as if in parody of ancient monastic orders.

History
The Brotherhood of the Knife was first raised by the Word Bearers to provide cannon fodder support for their surprise assault upon the Ultramarines Legion in the Battle of Calth during the Horus Heresy. The brotherhood's cultists conducted several massed attacks on those Ultramarines defending strategic positions after the Word Bearers' initial attack, including the Ultramarines' 21st Company that was guarding the railway approach to Numinus City.

Although its cultists were not well-disciplined, the brotherhood's numbers and suicidal tactics caused several grave casualties among the Ultramarines, weakening them in advance of the main assault launched by the World Bearers' Traitor Marines. During the fighting on Calth and elsewhere in Ultramar, the brotherhood was infamous for the sheer scale of the atrocities they committed against civilians.

The Brotherhood of the Knife continued to exist in the years after the Heresy. Large numbers of brotherhood cultists were deployed by the Dark Cardinal Kor Phaeron to fight alongside the Word Bearers during the Talledus War in the Talledus System after the birth of the Great Rift.