Between 1939 and 1945, nations all over the globe fought World War II, the largest and most costly conflict in history. The war had an enormous impact on world politics, shifting the balance of power from Western Europe to the United States and the Soviet Union.
During the 1930s, dictators undermined world peace.
The early years of World War II were marked by Axis victories.
In 1942 and 1943, the tide of the war began to turn as Allied forces won key victories.
Continued Allied successes led to victory over Germany and Japan in 1945.
As the war ended, new tensions developed between the United States and the Soviet Union.