A triangular division is a designation given to the way military divisions are organized. In a triangular organization, the division's main body is composed of three regimental maneuver elements. These regiments may be controlled by a brigade headquarters (more typical in World War I) or directly subordinated to the division commander. By contrast, in a square division, there were typically two brigades of two regiments. Other structures are possible, such as a pentomic division, where the division commander controls five maneuver elements, which was used in the United States Army in the late 1950s, with the regiments replaced by combined arms battlegroups.