World War II

World War II, or the Second World War, was a global military conflict, the joining of what had initially been two separate conflicts. The first began in Asia in 1937 as the Second Sino-Japanese War; the other began in Europe in 1939 with the German invasion of Poland.

This global conflict split the majority of the world's nations into two opposing military alliances: the Allies and the Axis powers. It involved the mobilization of over 100 million military personnel, making it the most widespread war in history, and placed the participants in a state of "total war", erasing the distinction between civil and military resources. This resulted in the complete activation of a nation's economic, industrial, and scientific capabilities for the purposes of the war effort. Over 60 million people, the majority of them civilians, were killed, making it the deadliest conflict in human history. The financial cost of the war is estimated at about a trillion 1944 U.S. dollars worldwide,making it the most costly war in capital as well as lives.

The Allies were victorious, and, as a result, the Soviet Union and the United States emerged as the world's leading superpowers. This set the stage for the Cold War, which lasted for the next 45 years. The United Nations was formed in hopes of preventing another such conflict. The self determination spawned by the war accelerated decolonization movements in Asia and Africa, while Europe itself began moving toward integration.

Background

In the aftermath of World War I, the defeated German Empire signed the Treaty of Versailles. This restricted German military and territorial growth and required the payment of massive war reparations. Civil war in Russia led to the creation of the communist Soviet Union which soon fell under the control of Joseph Stalin. In Italy, Benito Mussolini seized power as a fascist dictator promising to create a "New Roman Empire".The ruling Kuomintang (KMT) party in China launched a unification campaign against rebelling warlords in the mid-1920s, but was soon embroiled in a civil war against its former Chinese communist allies. In 1931, an increasingly militaristic Japanese Empire, which had long sought influence in China as the first step of its right to rule Asia, used the Mukden Incident as justification to invade Manchuria; the two nations then fought several small conflicts until the Tanggu Truce in 1933.

German troops at the 1935 Nuremberg RallyIn 1933, National Socialist Adolf Hitler became the leader of Germany and began a massive rearming campaign. This worried France and the United Kingdom, who had lost much in the previous war, as well as Italy, which saw its territorial ambitions threatened by those of Germany. To secure its alliance, the French allowed Italy a free hand in Ethiopia, which Italy desired to conquer. The situation was aggravated in early 1935