World War II was won by the Allied Powers, which primarily included the United States, the United Kingdom, and the Soviet Union, along with other countries such as France and China. Germany surrendered in May 1945, marking Victory in Europe Day (V-E Day), and Japan surrendered in September 1945, marking Victory over Japan Day (V-J Day)

. The Soviet Union bore the heaviest casualties and fought the largest battles on the Eastern Front, playing a crucial role in defeating Nazi Germany. The United States and the United Kingdom were also vital, with the U.S. providing significant military and economic support, including through the Lend-Lease program, and fighting major campaigns on multiple fronts. The UK and its Commonwealth forces contributed significantly in various theaters, including North Africa and the Atlantic

. In summary, the victory was a combined effort of the Allies, with the Soviet Union, the United States, and the United Kingdom as the main victors against the Axis powers of Germany, Japan, and Italy