1-2. A command post is a unit headquarters where the commander and staff perform their activities. The headquarters design, combined with robust communications, gives commanders a flexible mission command structure consisting of a main CP, a tactical CP, and a command group for brigades, divisions, and corps. Combined arms battalions are also resourced with a combat trains CP and a field trains CP. Theater army headquarters are resourced with a main CP and a contingency CP. (See appropriate echelon publications for doctrine on specific types of CPs and headquarters organizations.)