The Astra Militarum is a vast fighting formation and for its operations to go smoothly a substantial command structure is needed. Company Commanders are escorted by a hand-picked retinue of battle-scarred veterans who support their leader in the field. Depending on the situation, they can either lead the charge into the enemy or form the immovable centre of the Astra Militarum line.

Though much of an infantry regiment is made up of rank-and-file Guardsmen, those soldiers with an affinity for bulky and more complicated weaponry are often gathered together within a dedicated heavy weapons company. Individual squads are then assigned to other companies as platoon-support units, where they bolster the battle line and provide close fire support.