In June 1940, Germany's leader Adolf Hitler had triumphed in what he called "the most famous victory in history"—the fall of France. British craft evacuated to England over 338,000 Allied troops trapped along the northern coast of France (including much of the British Expeditionary Force (BEF)) in the Dunkirk evacuation (27 May to 4 June). British planners reported to Prime Minister Winston Churchill on 4 October that even with the help of other Commonwealth countries and the United States, it would not be possible to regain a foothold in continental Europe in the near future. After the Axis invaded the Soviet Union in June 1941, Soviet leader Joseph Stalin began pressing for a in Western Europe. Churchill declined because he felt that even with American help the British did not have adequate forces for such a strike, and he wished to avoid costly frontal assaults such as those that had occurred at the Somme and Passchendaele in World War I. Two tentative plans code-named Operation Roundup and Operation Sledgehammer were put forward for 1942–43, but neither was deemed by the British to be practical or likely to succeed. Instead, the Allies expanded their activity in the Mediterranean, launching the invasion of French North Africa in November 1942, the invasion of Sicily in July 1943, and invading Italy in September. These campaigns provided the troops with valuable experience in amphibious warfare.