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
Western European Union Luxembourg, and the Netherlands on 17 March 1948, establishing the Western Union (WU) - an intergovernmental defence alliance that also promoted economic, cultural and social collaboration. The need to back up the commitments of the North Atlantic Treaty with appropriate political and military structures led to the creation of the North Atlantic Treaty Organisation (NATO). In December 1950 the parties to the Treaty of Brussels decided to transfer the headquarters, personnel, and plans of the Western Union Military Organisation (WUDO) to NATO, whose Supreme Headquarters Allied Powers Europe (SHAPE) took over responsibility for the defence of Western Europe. The establishment