Origins of World War 2
There were actually two major starting points of how the war started. The Pacific theater started late 1931 with the Japanese invasion of Manchuria. This is sometimes referred to as the Mukden Incident. The major invasion of China by Japan was in 1937.
Japan had long been coveting mainland resources, invading China and Korea for centuries. Japan plotted an imperial takeover of Asia and the Pacific in the style of Western imperialism less than a century earlier. The US opposed this movement and placed embargoes on Japan. Searching for supplies and rebelling against US intervention, Japan embarked on its conquest. Hoping to keep the US Air Force out of Japan's way, Admiral Yamamoto led the attack on Pearl Harbor which launched the Americans into the Pacific theater conflict.
(Picture above: attack on Pearl Harbor)
The European theater started when Adolf Hitler went against the Treaty of Versailles which opressed Germany from strengthening their military force and weakened their economy. He defied the Treaty of Veresailles but reinforcing Germany's military war machine and they invaded Rhineland in 1936, annexed Austria in 1939 and reclaimed land from Czechoslovakia in 1938. While this was occuring, England and France did not do anything to precvent this. They didn't want to be involved in this. Hitler ordered a suprise attack on Poland in September 1, 1939. Since Poland signed a defensive pact with France and England, this act of aggression from Germany forced France and England to declare war on Germany, which they did on September 3, 1939. Thus launching the war in Europe.
