U.S. military planners and especially Army Chief of Staff George C. Marshall wanted an early U.S.-British invasion of France. They believed that a military diversion was necessary to keep the Soviet Union in the war and that the quickest way to end the war was to concentrate resources for a massive cross-Channel invasion. Toward that end, American planners wanted the earliest possible date for action. British Prime Minister Winston L. S. Churchill, who feared a repetition of the bloody stalemate in Flanders during World War I, preferred a gradual, more opportunistic approach that would commit major Allied military assets in the Mediterranean Theater. Chief of the Imperial General Staff General Sir Alan Brooke supported Churchill.
General Marshall directed Brigadier General Dwight D. Eisenhower and the War Plans Division to devise a cross-Channel invasion plan. Presented to Roosevelt as the Marshall Memorandum in March 1942, it considered two options: sledgehammer and roundup. sledgehammer was originally a British contingency cross-Channel invasion for late 1942, to be implemented only if the Soviet Union was in danger of collapsing or if German armies in the east were defeated and France became vulnerable. sledgehammer would utilize whatever forces were available. roundup, another British plan, envisioned an invasion of France by 48 divisions.
It is not clear how seriously the planners regarded sledgehammer, but roundup was actively considered. It called for 18 British and 30 U.S. divisions to invade the French coast somewhere between Le Havre and Calais in the spring of 1943. U.S. planners believed that 1943 was the earliest possible date for a large-scale invasion. They also thought it might be the only time such an invasion was possible, as by 1944, the Soviet Union might either have been driven from the war or else have been victorious and rendered unwilling to cooperate with an Allied invasion of France.
Under heavy U.S. pressure, Churchill agreed to carrying out roundup no later than April 1943. Privately, however, the British worked to scuttle the cross-Channel plan by diverting resources to more modest and, according to them, more realistic objectives. In the summer of 1942, with Roosevelt unwilling to risk defeat in Europe, the Americans reluctantly agreed to Operation gymnast, a plan to invade French North Africa, supposedly without prejudice to the future of roundup. The Dieppe raid of 19 August 1942, however, destroyed any illusions about roundup. The cross-Channel invasion of France was postponed; its final incarnation, 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.