World War 2

World War II (abbreviated WWII), or the Second World War, was a worldwide conflict which lasted from 1939 to 1945. Caused by the expansionist and hegemonic ambitions of Germany, Italy, and Japan, World War II was a confluence of two conflicts respectively started in China (the Second Sino-Japanese War), and in Poland (the Invasion of Poland). This global conflict split a majority of the world's nations into two opposing camps: the Allies and the Axis. Spanning much of the globe, World War II resulted in the deaths of over 72 million people, making it the deadliest conflict in human history.

Not only fought between nations, World War II was the first large ideological war in history, which helps to explain why resistance and collaboration groups in occupied Europe and Asia could still operate in spite of contrary national governments and armies, or how a resistance could exist in the heart of Nazi Germany.

World War II was the most widespread war humanity has ever experienced, mobilizing over 100 million soldiers from 61 nations, with hostilities covering over 20 million km². Total war erased the distinction between civil and military resources and saw the complete mobilization of a nation's economic, industrial, and scientific capabilities for the purposes of the war effort; nearly two-thirds of those killed in the war were civilians. Massive air raids against civilian targets, initially by the Axis in Europe (Coventry, England, Rotterdam, Netherlands) and in Asia (Shanghai and Chongqing, China), then by the Allies (Tokyo, Japan, Dresden (35,000 dead) and Hamburg, Germany), took additional lives. And, for the first and so far only time, nuclear weapons were used in combat: two atomic bombs released by the United States over Japan devastated Hiroshima and, three days later, Nagasaki.

Totaling the amount of destruction is difficult, but it has certainly not been exceeded, in any single conflict, since the war's conclusion. The moral damage caused by the atrocities committed by both sides was an unquestionable blow to societal progress.

These atrocities include the deportation of entire populations (principally Jews, Slavs, and Roma), certain categories of people (for instance, homosexuals, Jehovah's Witnesses, or the disabled) but also political dissidents (for instance, Socialists, Communists or Labour Unionists) to labour, concentration, and extermination camps by the Nazis, the forced conscription of millions of East Asians living under the rule of Imperial Japan into military, labour and sexual service, the forced internment of Japanese-Americans within the U.S., and specific exactions such as the Nanking and Manila massacres. Other infamous actions include the reprisals against various uprisings, the experiments on human beings which Nazi doctors, such as SS Josef Mengele, and the Japanese Unit 731 conducted.

As a result of World War II, the United States and Soviet Union emerged as the world's two leading superpowers, dominating the world's stage for the next 40 years. The dominance of Europe faded due to the rise of Asian, Arabian, and eventually African decolonization/independence movements, which was roughly complete by the 1960s. Paradoxically, while World War II was the last, and probably worst, conflict in European history, it has led to a desire for unification in order to avoid future conflicts, which has transformed the difficult process of reconstruction into an unprecedented opportunity for prosperity.