- United States: The US entered the war in December 1941 after the attack on Pearl Harbor by the Imperial Japanese Navy. It played a crucial role in the war, providing military and economic support to its allies, and engaging in combat operations in various theaters, including the Pacific, North Africa, and Europe.
- United Kingdom: The UK was one of the main Allied Powers throughout the war. It played a vital role in the Battle of Britain, defending against German air raids in 1940, and was involved in numerous campaigns, including the North African Campaign and the D-Day landings in Normandy.
- France: France was initially defeated by Germany in 1940, but the Free French Forces continued to fight alongside the Allies. France played a significant role in the liberation of its own territory and in subsequent campaigns in Europe.
- Soviet Union: The Soviet Union was a key Allied Power and bore the brunt of the fighting on the Eastern Front against Nazi Germany. The Battle of Stalingrad in 1942-43 was a turning point in the war, and the Soviet Union played a crucial role in defeating Germany.
- China: China was involved in the war against Japan from 1937, even before the official start of World War II. It fought a long and艰苦的struggle against the Japanese occupation and received support from the Allies.
Axis Powers:
- Germany: Germany was the primary aggressor in World War II, led by Adolf Hitler and the Nazi Party. It invaded and occupied numerous countries in Europe, leading to the outbreak of war in 1939. Germany's military strategy involved Blitzkrieg tactics and rapid advances, but its expansionist ambitions eventually led to its defeat.
- Italy: Italy joined the Axis Powers in 1940 and participated in campaigns in North Africa, Eastern Europe, and the Mediterranean. Italy was defeated by Allied forces in 1943 and switched sides to join the Allies.
- Japan: Japan was the primary Axis Power in the Pacific region. It engaged in aggressive expansionism, seeking to establish a "Greater East Asia Co-Prosperity Sphere." Japan's attack on Pearl Harbor brought the US into the war, and the Allies eventually defeated Japan in 1945 with the use of atomic bombs.