Key events from 1939–1945 · Simple explanations · Quiz · Grades 5–8
World War II was the largest and deadliest conflict in human history, lasting from 1939 to 1945. It involved countries from every continent and resulted in an estimated 70 to 85 million deaths. The war was fought between two major alliances: the Allied Powers (including the United States, United Kingdom, Soviet Union, and France) and the Axis Powers (Germany, Italy, and Japan).
The war began when Nazi Germany, led by Adolf Hitler, invaded Poland on September 1, 1939. Key events include the Battle of Britain in 1940, Germany's invasion of the Soviet Union in 1941, Japan's attack on Pearl Harbor that brought the United States into the war in December 1941, and the D-Day invasion of Normandy on June 6, 1944. The war in Europe ended on May 8, 1945, and the war in the Pacific ended on August 15, 1945.
The war led to enormous changes in the world, including the founding of the United Nations, the beginning of the Cold War between the United States and the Soviet Union, and the start of the civil rights movement. The Holocaust, in which six million Jewish people were murdered by the Nazi regime, remains one of the most important lessons in human history about the dangers of hatred and prejudice.
This interactive timeline lets students explore the major events of World War II year by year, learn about key figures and battles, and understand how the war shaped the modern world. Suitable for history students in grades 5 through 8.
Last reviewed: April 2026