One of the most significant events in the history of Allied Command Europe was France's withdrawal from NATO's integrated military structure, which made it necessary for SHAPE and several other ACE headquarters to leave French territory. The split between France and NATO's military structure had been developing for a number of years, as successive French governments had become increasingly dissatisfied with what they perceived as Anglo-American domination of the command structure and insufficient French influence throughout the command.
By late December 1965 French President Charles de Gaulle was ready to take action. He had just been elected for the second time, France had acquired its own nuclear capability, his attempts to establish a Franco-British–American Security Directorate and gain some French control over American nuclear weapons based in France had failed, and he sought a more independent role for France in order to maximise its global influence and status. President de Gaulle also disagreed with the United States' intention to replace the strategy of "Massive Retaliation” with "Flexible Response” because he believed that this meant a weakening of the U.S. commitment to defend Europe with nuclear weapons. Increasingly critical of the developments in NATO, he described the military integration practised at SHAPE and its subordinate headquarters as obsolete and said that it was designed to ensure French subordination to U.S. policy.
In February 1966 President de Gaulle stated that the changed world situation "stripped of justification” NATO's military integration and that France was therefore re-establishing her sovereignty over French territory. As a result, all forces within France's borders would have to come under French control by April 1969. Soon afterward, France announced that it was withdrawing from the headquarters of Allied Command Europe and that SHAPE and its subordinate headquarters Allied Forces Central Europe (AFCENT) must leave French territory by April 1967.
Despite his political differences with NATO, President de Gaulle
maintained a good relationship with SACEUR Leminitzer and
awarded him the Grand Cross of the Legion of Honour in 1967
The allies attempted unsuccessfully to persuade the French government to reconsider, and France then withdrew the vast majority of its military personnel from NATO military headquarters in July 1966. The allies moved quickly to find new hosts for the headquarters that would have to leave France. They decided to move NATO's political headquarters from French territory as well.
The Netherlands was selected to host AFCENT and Belgium became the host nation for both NATO and SHAPE. SACEUR Lyman L. Lemnitzer had hoped that SHAPE could be located near to NATO Headquarters, as had been the case in Paris but the Belgian authorities decided that SHAPE should be located at least 50 kilometers from Brussels, NATO's new location, because SHAPE was a major wartime military target. They also said that SHAPE had to be placed on land already owned by the government in order to limit costs and construction time.
The Belgian government then offered Camp Casteau, a 200-hectare Belgian Army summer training camp near Mons, a former mining area in need of additional economic investment. To overcome SHAPE's objections about the distance from Brussels, the Belgian government agreed to build a high-speed motorway connecting Mons and Brussels. In September 1966 NATO agreed that Belgium should host SHAPE at Casteau. Six and a half months remained before the French deadline for SHAPE to leave France would expire. A massive seven-day-a-week building program began, coordinated between the Belgian central and local authorities, the building consortium and SHAPE. Highest priority was given to building command and control facilities.
Closing Ceremony at Rocquencourt
Opening Ceremony 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. SACEUR Lemnitzer called the construction effort "a miracle of achievement” and praised the Belgian authorities and workmen for their efforts to ensure that SHAPE had a new headquarters in a remarkably short time.