While the Nazis and the Japanese built their savage empires, Great Britain, the United States, and the Soviet Union joined together in a military pact Churchill termed the Grand Alliance. Disagreements between the Soviets and the capitalist powers during the course of the war sowed mutual distrust, but there were broad areas of consensus. The Grand Alliance concurred on a policy of “Europe first.” Only after Hitler was defeated would the Allies mount an all-out attack on Japan, the lesser threat. The Allies also agreed to concentrate on immediate military needs, postponing tough political questions about the eventual peace settlement that might have divided them. To further encourage mutual trust, the Allies adopted the principle of the unconditional surrender of Germany and Japan. This policy cemented the Grand Alliance because it denied Hitler any hope of dividing his foes. It also meant that Soviet and Anglo-American armies would almost certainly be forced to invade and occupy all of Germany, and that Japan would fight to the bitter end.

The combined might of the Allies forced back the Nazi armies on all fronts (see Map 27.3). Through early 1942, heavy fighting between British and Axis forces had resulted in significant German advances in North Africa. At the Second Battle of El Alamein (el al-uh-MAYN) in October–November 1942, however, British forces decisively defeated combined German and Italian armies and halted Axis penetration of North Africa. Shortly thereafter, an Anglo-American force landed in Morocco and Algeria.

After driving the Axis powers out of North Africa, U.S. and British forces invaded Sicily in the summer of 1943 and mainland Italy that autumn. Mussolini was overthrown by a coup d’état, and the new Italian government publicly accepted unconditional surrender. In response, Nazi armies invaded and seized control of northern and central Italy, and German paratroopers rescued Mussolini in a daring raid and put him at the head of a puppet government. Facing stiff German resistance, the Allies battled their way slowly up the Italian peninsula.

The spring of 1943 brought crucial Allied victories at sea and in the air. In the first years of the war, German submarines had successfully attacked North Atlantic shipping, severely hampering the British war effort. New antisubmarine technologies favored the Allies. Soon massive convoys of hundreds of ships were streaming across the Atlantic, bringing much-needed troops and supplies from the United States to Britain.

The German air force had never really recovered from its defeat in the Battle of Britain. With almost unchallenged air superiority, the United States and Britain now mounted massive bombing raids on German cities to maim industrial production and break civilian morale.

The worst German defeats came at the hands of the Red Army on the eastern front. Although the Germans had almost captured the major cities of Moscow and Leningrad in early winter 1941, they were forced back by determined Soviet counterattacks. The Germans mounted a second and initially successful invasion of the Soviet Union in the summer of 1942, but the campaign turned into a disaster. The downfall came at the Battle of Stalingrad, when in November 1942 the Soviets surrounded and systematically destroyed the entire German Sixth Army of 300,000 men. In summer 1943 the larger, better-equipped Soviet armies took the offensive and began to push the Germans back along the entire eastern front (see Map 27.3).