American planners, especially Army Chief of Staff George C. Marshall, advocated a cross-Channel invasion as the best means to end the war as quickly as possible. An invasion of France by the western Allies would also relieve German pressure on the Soviet Union. British Prime Minister Winston L. S. Churchill, who feared a repetition of the bloody stalemate in Flanders during World War I, sought to commit major Allied military assets in the Mediterranean Theater and involve the United States in efforts to contain Soviet power. Chief of the Imperial General Staff General Sir Alan Brooke supported that position.
General Marshall directed Brigadier General Dwight D. Eisenhower of the War Plans Division to draw up a plan, which Marshall then presented to Roosevelt in March 1942, for a British-U.S. invasion of the French coast somewhere between Le Havre and Calais. Known as the "Marshall Memorandum," it outlined two military options. The first of these was sledgehammer. Originally conceived by the British as an emergency invasion of France to prevent a Soviet collapse (or to take advantage of the situation if German forces were defeated in the east and France become vulnerable to invasion), sledgehammer was in fact a high-risk operation. It is a matter of some debate as to whether the War Department actually considered sledgehammer viable. The second option, roundup, called for a 48-division invasion in early 1943.
Although the Marshall Memorandum emphasized that roundup in 1943 was the preferred solution, it noted that even a failed small cross-Channel invasion of France would be preferable to dispersing Allied military assets elsewhere. The U.S. planners believed that the spring of 1943 was not only the earliest possible date for an all-out invasion of France, it could be the only date, as by 1944 the Soviet Union might have been driven from the war
Churchill fought against sledgehammer and roundup, believing that a cross-Channel invasion, even in 1943, was too risky. He favored the Mediterranean strategy, known as gymnast, in which British and French forces would invade and conquer French North Africa, supposedly without prejudicing roundup. The Dieppe Raid of 19 August 1942 destroyed any illusions about the possibility of an Allied invasion of France in 1942 or even 1943. The cross-Channel invasion of France, ultimately known as Operation overlord, did not occur until June 1944.
Spencer C. Tucker
Ambrose, Stephen E. Eisenhower: Soldier, General of the Army, President-Elect. New York: Simon and Schuster, 1983.; D'Este, Carlo. Decision in Normandy. New York: E. P. Dutton, 1983.; Eisenhower, David. Eisenhower at War, 1943–1945. New York: Random House, 1986.; Hastings, Max.