World War II

The deadliest international conflict in history, World War II was fought from 1939 to 1945 between two major alliances: the Axis (primarily Nazi Germany, fascist Italy, and Imperial Japan) and the Allies (primarily the United Kingdom, the Soviet Union, the United States, and France). An estimated 60 million people--military personnel and civilians worldwide--were killed during the war.

The outbreak of World War II was triggered by Nazi Germany's 1938 annexations of Austria and the Sudetenland, followed by its invasion of Poland in September 1939. The war spread rapidly as a result of aggressive expansionism on behalf of Germany and the other Axis powers. Using "Blitzkrieg" tactics, Germany had occupied much of Western Europe by mid-1941. The Nazi invasion of the Soviet Union in 1941 and the Japanese attack on Pearl Harbor in the same year created a conflict on a global scale, drawing the Soviet Union and the United States into the war on the side of the Allies.

The conflict spanned multiple geographical regions, including Europe, the Pacific, North Africa, and Asia. In Europe, Nazi Germany rapidly conquered much of the continent, including France, Denmark, Norway, and the Low Countries. The brutal Eastern Front became one of the deadliest theaters of the war. Brutal military campaigns resulted in millions of casualties on both sides. Behind the front civilians were subject to significant atrocities and genocide, most notably the systematic murder of six million Jews in the Holocaust, along with millions of others deemed undesirable by the Nazi regime. The Pacific theater witnessed intense naval battles, island-hopping campaigns, and the use of devastating new weapons like the atomic bomb.

In Europe, the Soviet victory at Stalingrad in 1943 and the Allied invasion at Normandy on June 6, 1944 (D-Day), marked a turning point in the war, opening a Western Front and forcing the gradual retreat of Axis forces. In April 1945, as the Allies closed in on Germany from both east and west, Hitler committed suicide, and Germany surrendered in May 1945, ending the war in Europe. Intense fighting in the Pacific continued until August, when the United States dropped atomic bombs on Hiroshima and Nagasaki, forcing Japan's surrender on August 15.

World War II left a profound legacy, reshaping the global balance of power and leading to the emergence of the United States and the Soviet Union as superpowers. It also laid the foundation for the establishment of the United Nations and the Cold War between the Western Allies and the Soviet Union.