World War II is generally held to have begun on September 1, 1939, with the German invasion of Poland, and Britain and France declared war on Germany two days later. The war continued until 1945, though the Treaty of Peace with Japan was not signed until 1951. The Commonwealth remained the only major force continuing the fight against the Axis in North Africa and in extensive naval warfare. In June 1941, the European Axis invaded the Soviet Union, opening the largest land theatre of war in history and tying down the major part of Axis military power. In December 1941, Japan, already at war with China since 1937 and aiming to establish dominance over East Asia and Southeast Asia, attacked the United States and European possessions in the Pacific Ocean and quickly conquered a significant part of the region. The Axis advance was stopped in 1942 after Japan's defeat in a series of naval battles and the devastating defeats of European Axis troops in North Africa and at Stalingrad. In 1943, after a series of German defeats in Eastern Europe, the Allied invasion of Fascist Italy, and American victories in the Pacific, the Axis lost strategic initiative and passed to strategic retreat on all fronts. In 1944, the Western Allies invaded France, while the Soviet Union regained all territorial losses and invaded the territory of Germany and its allies. The war in Europe ended with the capture of Berlin by Soviet troops and Germany's unconditional surrender on May 8, 1945. By that time, the Japanese Navy had been defeated by the United States, and invasion of the Japanese archipelago, the Home Islands, had become imminent. The war ended with total Allied victory over Germany and Japan in 1945. It significantly altered the world's political alignment and social structure: the United Nations was established to foster international cooperation and prevent future conflicts, the Soviet Union and the United States emerged as rival superpowers and set the stage for the Cold War, the influence of European great powers began to decline, decolonization began in Asia and Africa, and many countries whose industries had been badly damaged moved toward economic recovery as political integration emerged across the world in an effort to stabilize postwar relations peacefully.