The war in Europe involved aid to Britain, her allies, and the Soviet Union, with the US supplying munitions until it could ready an invasion force. US forces were first tested to a limited degree in the North African Campaign and then employed more significantly with British Forces in Italy in 1943–45, where US forces, representing about a third of the Allied forces deployed, bogged down after Italy surrendered and the Germans took over. Finally the main invasion of France took place in June 1944, under General Dwight D. Eisenhower. Meanwhile, the US Army Air Forces and the British Royal Air Force engaged in the area bombardment of German cities and systematically targeted German transportation links and synthetic oil plants, as it knocked out what was left of the Luftwaffe post Battle of Britain in 1944. Being invaded from all sides, it became clear that Germany would lose the war. Berlin fell to the Soviets in May 1945, and with Adolf Hitler dead, the Germans surrendered.