How did World War 2 begin?
The question "How did World War 2 start?" or "What started World War 2?" can be considered distinct from "What caused World War 2?" For the latter, see the Related Question link.
There are many views on exactly when and where World War 2 started, and what started it.
One view is that there was only one world war. It started in 1914 and finished in 1945, with a break from 1918-1939 while the Germans regrouped. (Kaiser Wilhelm, or at least the German General Staff, had similar foreign policy aims to those of Hitler: a vast program of expansion with visions of world domination.) However, this view of one long war, with a 20 year truce is often not meant literally, and needs treating with caution. Hindsight easily distorts. It is inaccurate to view the whole of the interwar period as one vast build-up to World War 2.More commonly, people believe World War 2 started in 1939. On 1 September 1939, Hitler and the Nazis faked a Polish attack on a minor German radio station in order to justify a German invasion of Poland. An hour later Hitler declared war on Poland stating one of his reasons for the invasion was because of "the attack by regular Polish troops on the Gleiwitz transmitter."
France and Britain had a defensive pact with Poland. This forced France and Britain to declare war on Germany, which they did on September 3.
Japan had long been coveting mainland resources, invading China and (en route) Korea for centuries. Under the guise of The Co-Prosperity Sphere (8-Lands Under One Umbrella), 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 Oriental conquest. Hoping to keep the US Air Force out of Japan's way, Admiral Yamamoto led the attack on Pearl Harbor. Unfortunately they opened fire 30 minutes before the proclamation of war was officially delivered, so many viewed it as a violation of military convention (Adm. Yamamoto regretted this fact; he admired Western military practices).
Note that one reason many people say WWII started in 1939 by Hitler's invasion of Poland instead of by Japan in 1937 is because the former is the moment when the first main Allied nation declared war on an Axis nation (Britain declares war on Germany). Rather than be specific and say the first shots of origin started with Japan's invasion, it is pointed out that no main Allied nation had declared war at that time.
Here's more from Wiki s contributors:
- For the European Theater it began with Germany's attack on Poland which drew England and France into the fray. Pearl Harbor marked the start of the Pacific Theater. Germany's declaration of war against the US folded them together into a worldwide conflict.
- It began when Britain and France declared war on Germany in response to Germany's invasion of Poland.
Japan bombed US planes and installation at Pearl Harbor, drawing the US into the war.