The Chamber Militant is the military arm of each branch of the Imperial Inquisition. The Ordo Xenos (Alien Hunters) is served by the Deathwatch Space Marines, the Ordo Malleus (Daemon Hunters) by the elite Grey Knights Chapter and the Ordo Hereticus (Witchhunters) by the Orders Militant of the Adepta Sororitas, the Sisters of Battle. Usually, these organisations are only called upon by their Ordo in cases of dire need, when all other options to deal with a given situation have been exhausted. For example, the Grey Knights are called upon only when a daemonic infestation has grown to the point that the efforts of a lone Inquisitor and his chosen Acolytes and other agents can no longer contain it.

Sources

• Dark Heresy Core Rulebook (RPG)
• Deathwatch: Core Rulebook (RPG)
• Codex: Grey Knights (5th Edition)
• Dark Heresy: Blood of Martyrs (RPG)