Master of the Watch

A Master of the Watch is a Space Marine Captain who in a Codex Astartes-compliant Chapter serves as the sentinel of the Fortress-Monastery. He is responsible for the defence of his Chapter's base of operations and home world in the absence of the Chapter Master. This title is given to the commander of the designated Company that is currently charged with the garrisoning of the fortress-monastery, which is allotted to a different company on a rotational basis.