World War II

The conflict grew from expansionist policies pursued by Nazi Germany, Fascist Italy and Imperial Japan. Japan had invaded Manchuria in 1931 and China proper in 1937, so the war in Asia predated the commonly used European starting date. In Europe, Germany annexed Austria and dismantled Czechoslovakia before invading Poland on 1 September 1939. Britain and France declared war on Germany two days later, beginning the European war.

Germany, Italy and Japan were the central Axis powers. The Allied coalition included Britain, France, China and, after Germany invaded the Soviet Union in 1941, the Soviet Union; the United States entered the war after Japan attacked Pearl Harbor in December 1941. Fighting extended across Europe, North Africa and the Atlantic, as well as China, Southeast Asia and the Pacific. The war was not a single continuous front: occupied countries, resistance movements, colonial forces and local populations experienced it in different ways.

In 1941 Germany's invasion of the Soviet Union opened the vast Eastern Front, while Japan's attack on Pearl Harbor widened the conflict to include the United States. Allied forces began the liberation of German-occupied western Europe with the Normandy landings of 6 June 1944; Soviet forces advanced from the east. Germany surrendered in May 1945. Japan accepted surrender terms in August, after the atomic bombings of Hiroshima and Nagasaki and the Soviet Union's entry into the war against Japan; its formal surrender was signed on 2 September 1945.

The Holocaust was the Nazi German regime's systematic, state-sponsored persecution and murder of six million European Jews, carried out with allies and collaborators. Nazi Germany also persecuted and murdered millions of other people. These crimes unfolded amid occupation, forced displacement, forced labour, mass shootings, bombing and deprivation. Civilians were not simply bystanders: their experiences differed according to where they lived, the occupying power, race, religion, political status and the course of military operations.

The war left extensive physical destruction, displacement and profound political change. Germany and Japan were defeated and occupied, while the United States and Soviet Union emerged as rival superpowers, helping shape the postwar international order. In 1945, representatives of 50 countries drafted and signed the United Nations Charter; the United Nations came into existence on 24 October, with maintaining international peace among its central purposes.