Promoted to brigadier general in April 1940, Béthouart led the Franco-Polish expeditionary force that took part in the Norwegian Campaign of that spring. After France surrendered to Germany in June 1940, he initially remained with Vichy forces and took over the Casablanca Division in southern Morocco. By late 1942, Béthouart was prepared to collaborate with U.S. forces invading North Africa, and he negotiated with American representatives, including U.S. civilian Robert Murphy. Béthouart promised that men under his command would occupy all key points and welcome the invaders. At the last moment in the confused meetings and negotiations, he also informed his superior, Governor-General Charles Noguès, of events. Noguès had earlier warned the Americans that his forces would oppose them, and he ordered Béthouart and a subordinate arrested and tried for treason. Noguès then ordered their execution, a command U.S. Army Major General George S. Patton Jr. was able to countermand following the American landing.
From December 1942, Béthouart headed the French mission in Washington, negotiating large-scale military aid from the United States. Returning to Algiers, he became chief of the National Defense Staff, organizing the French Army of Africa in preparation for the invasion of France. In August 1944, Béthouart commanded I Corps of the First French Army in the invasion of southern France, through the Vosges Mountains into Alsace and across the Rhine as far as the southern bank of the Danube. His men saw particularly heavy action in the Colmar region.
Béthouart subsequently headed French occupation forces in Austria. In 1949, he became a full general. After retiring in 1955, he entered politics and became a senator. Béthouart died in Fréjus in southern France, on 17 October 1982.
Aglion, Raoul. De Gaulle et Roosevelt: La France Libre aux États-Unis. Paris: Plon, 1984.; Béthouart, M. E. Cinq années d'espérance, 1939–45. Paris: Plon, 1968.; Béthouart, M. E. Dès hécatombes glorieuses au désastre (1914–1940). Paris: Plon, 1972.; Lemaigre-Dubreuil, Jacques. Les relations franco-américains et la politique des généraux. Paris: Publications Elysées, 1949.; Paxton, Robert O. Parades and Politics at Vichy: The French Officer Corps under Marshal Pétain. Princeton, NJ: Princeton University Press, 1966.