The chief antagonists were Germany, Italy, and Japan — the Axis Powers — on one side and the United States, Great Britain, the Soviet Union, France, and China — the Allied Powers — on the other.

In Europe, Germany had been preparing for this war since 1933, when Adolph Hitler came to power. After his attack on Poland, he quickly conquered many European nations including Austria, Czechoslovakia, Norway, and Denmark. Germany's ally Italy was also expanding her borders by conquering Albania. Another ally, Japan, had already invaded China in 1931.

On the morning of December 7, 1941, Japan attacked Pearl Harbor, Hawaii — an American naval base. Japanese warplanes bombarded the American naval fleet stationed at Pearl Harbor, and the damage was enormous. Nineteen warships were hit and 2,323 sailors and soldiers were killed. Most important, the attack showed how vulnerable America was and gave the country a personal stake in the war. The next day, America declared war on Japan and then on Germany and Italy the following day.

Soon, war had spread over the globe. World War II was the most widespread and the most destructive war in history. Battles were fought in Europe, Asia, and Africa. Over 100 million people, both soldiers and civilians, died. It lasted from 1939 to 1945, and eventually involved all the Great Powers and most of the smaller nations of the world.

For the next four years, Allied forces fought the Axis powers. On June 6, 1944, American, British, and Canadian troops landed on the beaches of Normandy, France. It was a huge effort involving months of secret preparations, thousands of ships and troops. It was called D-Day, and it was a success. It marked the turning point in World War II when the Allied forces began to win their fight against the Axis powers.

In Europe, the war was won on May 8, 1945, nine days after Hitler committed suicide. In Japan, two atomic bombs were dropped on Hiroshima and Nagasaki on August 6 and 9. Over 140,000 people were killed instantly, and hundreds of thousands died in the following years from the effects of nuclear radiation. On September 2, 1945, the Japanese signed the official document of surrender, and World War II officially ended.

Learn about the devastation and difficulty of living during World War II from the diary of Piper Davis. To learn more about World War II, explore World War II Remembered.

WWII Timeline

September 1, 1939: Germany invades Poland. Great Britain and France declare war on Germany. May 10, 1940: Winston Churchill replaces Neville Chamberlain as prime minister of Great Britain. May thru June 1940: At Dunkirk, 350,000 British, French, and Belgian soldiers are rescued by sea from the German onslaught. November 5, 1940: Franklin Roosevelt is elected for an unprecedented third term in the United States. December 7, 1941: Japanese attack Pearl Harbor, and the United States enters the war. 1942: Battles of Midway in the Pacific (June), El Alamein in Egypt (Oct.), and Stalingrad (Sept. 1942–Feb. 1943) in Russia are turning points of the war. January 1943: Casablanca Conference to settle future Allied strategy. July 1943: Mussolini government collapses. Uprising of the Warsaw ghetto. November 1943: Tehran Conference was the first meeting of U.S. president Franklin Roosevelt, British prime minister Winston Churchill, and Soviet premier Joseph Stalin in Teheran, Iran. The leaders discussed questions of military strategy and decided that Britain and the U.S. would lead the invasion of France in June 1944. June 6, 1944: D-Day, Allied invasion of France. August 25, 1944: Liberation of Paris. February 1945: Yalta Conference to plan final months of the war. April 29, 1945: Liberation of the Dachau concentration camp. February 19 to March 16, 1945: Battle of Iwo Jima. May 8, 1945: VE Day (Victory in Europe) is celebrated when Germany surrenders. August 1945: Atomic bomb dropped on Hiroshima (August 6) and Nagasaki (August 9). Surrender of Japan (August 14).