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
Gustave Fourreau - Major) on July 1, 1959. He was assigned to the 13th Demi-Brigade of the Foreign Legion 13 DBLE on four different occasional tours. The first assignment was at Bougie on July 22, 1960, on August 10, 1960, on November 3, 1960, then on November 17, 1961. He was then nominated to the 1st Mounted Chasseur Groupment () at Reims. He was promoted to the rank of Lieutenant-colonel, on October 1, 1964. In October, he was nominated to the Command of the general staff headquarters of Supreme Allied Armed Forces () in Europe, the Supreme Headquarters Allied Powers Europe SHAPE.