Plans for the Allied Invasion of France
Even though military resources in Britain were meager after the withdrawal from France in 1940, British forces soon began to plan a return to the Continent. In September 1941, the British Chiefs of Staff charged Adm. Lord Louis Mountbatten (later 1st Earl Mountbatten of Burma), who headed the Combined Operations Headquarters, with investigating the technical problems of amphibious operations. Not long afterward the British joint planners drew up the first formal plan for a cross-Channel attack. This plan, which was called Roundup, assumed a marked deterioration of German strength. Projecting the use of relatively small British forces, it was designed to disrupt German withdrawal to the homeland in the final phase of the war.
Though American military officers were in England as observers as early as October 1940, the World War II alliance between the English-speaking nations began to take definite shape only in January 1941. This was the month when American and British military officers met in Washington for conversations that became known as ABC-l. The agreements reached-that the two nations were to maintain joint planning staffs in Washington and London and that, if forced into war with both Japan and Germany, the United States would join Britain in defeating Germany first-started the chain of events that led to the eventual cross-Channel invasion and victory in Europe. It was two months later, in March, when Congress passed the Lend-Lease Act, which authorized the United States to provide war materials for nations under Axis attack. By June, with the American observers in London having become the Special Observer Group and the British having sent representatives to Washington, the two countries were in close liaison. Though the United States still was not at war, American troops replaced British troops in Iceland in July 1941, and later in the summer began to construct naval and air bases in the United Kingdom, ostensibly for British use.