Supreme Headquarters Allied Powers Europe government offered Camp Casteau, a 2 km² Belgian Army summer training camp near Mons, which was an area in serious need of additional economic investment. In September 1966, NATO agreed that Belgium should host SHAPE at Casteau. SHAPE closed its facility at Rocquencourt near Paris on 30 March 1967, and the next day held a ceremony to mark the opening of the new headquarters at Casteau. The drawdown of the British Mediterranean Fleet, the military difficulties of the politically decided command structure, and the withdrawal of the French from the military command structure forced a rearrangement of the command arrangements
Supreme Headquarters Allied Expeditionary Force with the American 6th Army Group (6 AG) under the command of Lieutenant General Jacob L. Devers. During the invasion of southern France, the 6 AG was under the command of the Allied Forces Headquarters (AFHQ) of the Mediterranean Theatre of Operations, but after one month command passed to SHAEF. By this time, the three Army Groups had taken up the positions on the Western Front in which they would remain until the end of the war—the British 21 AG to the North, the American 12 AG in the middle and the 6 AG to the South. By December 1944,