World War II

Allied designations for the various theaters of operations.

World War II (1931-1945) was the most destructive global war in human history, killing 53 million people. World War II in Asia was foreshadowed by the Japanese invasion of Manchuria in 1931 and began formally with the invasion of China by Japan of 1937. World War II in Europe arguably began with the ascension of Adolf Hitler and the Nazi Party to power in Germany in 1933, although many Western governments did not immediately understand the nature of the growing threat from the Nazis. World War II in Europe also should not be regarded as entirely separate from the Spanish Civil War (1936–39), whose 200,000 fatalities due to systematic murder, mob violence, and torture provided a breeding ground for mass atrocities later committed the Nazis. World War II also included the Holocaust, the state-sponsored murder of 6 million Jews by the Nazis, who also systematically murdered (or placed in camps to die) many more millions of people besides Jews, including political prisoners, Roma, Soviet prisoners of war, homosexuals, criminals, Jehovah’s Witnesses, and handicapped people living in institutions.

With battles in Europe, Africa, Asia and the South Pacific, the "Allies" (led mainly by the UK, US, and Soviet Union) eventually stopped the aggressively expanding "Axis" (mainly Germany and Japan). Hostilities in Europe formally ended after Nazi Germany collapsed in May of 1945. And in August of 1945, the United States destroyed the Japanese cities of Hiroshima and Nagasaki with newly developed atomic bombs, killing around 355,000 civilians and leading to Japan's total surrender.

This war, more than any other, propelled nations towards total war, a complete social, political, military, and economic commitment of a nation to war. Thus the war stimulated unprecedented levels of productivity and generated a wide variety of new technologies. The nations had been mobilized in the interests of many opposing ideologies, often seeking the unconditional surrender of their enemies. As whole populations were materially and politically, if not militarily, invested in the war effort, the distinction between combatant and non-combatant became blurred. Furthermore, many of these ideologies preached ideas of racism and genocide. Thus the level of civilian causalities in this war far surpasses any other in human history.

This war also marks the end of European domination of the globe and the rise of a bi-polar world dominated by two superpowers, the United States and the Soviet Union. The war also broke the ability of the remaining colonial powers (mainly Great Britain, France, Japan, and the Netherlands) to hold and maintain their empires. Thus the war also sparked a period of decolonization afterward. In the Commonwealth nations, official histories of the war use the term Second World War. This style also follows literally translations of other nations' official designation for the conflict, e.g. Zweiter Weltkrieg in German. The official histories of the United States refer to the conflict as World War II or World War Two, and that term is now often used in Canada and the UK as well. Parts of the world, especially Latin America, were largely unaffected directly by the conflict, with significant concentrations of activity in the European, north African, Russian, and Pacific theaters.