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.
The War in EuropeOne 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.
The War in the PacificSome say World War 2 started in 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 (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.
The War in AfricaSome people consider the war in Africa as starting with the 1935 invasion of Ethiopia by Italy. However, few Italians take the view that Italy was at war from 1935-1945.Here's more from Wiki s contributors:
Well Adolf Hitler began rearming Germany, and taking countries that he believed belonged to Germany. Great Britain and France warned him, if he invaded Poland they would declare war. Well obviously, Germany invaded and started World War Two.
While this is true, some people believe the world was feuding after World War I, and while it did technically end, it did not end in some political ways, and World War II was actually just the fighting continuing.
It began with the German invasion of Poland.
After Germany's defeat in WWI, Adolf Hitler ignored the terms of the Treaty of Versailles and gradually began building up his power-base. He invaded Austria in 1938 and Czechoslovakia in 1939, after he had already had part of Czechoslovakia handed to him by France and Britain, who wanted to avoid another war.
As tensions escalated in the lead-up to WWII, Nazi leader Adolf Hitler refused to bow to further pressure from Britain and France. At midday on 31 August, 1939, Hitler signed an order to attack Poland, and German forces move to the frontier. They staged an attack by Poland, dressing Nazi S.S. troops in Polish uniforms and leaving behind dead German prisoners in Polish uniforms as evidence of the 'Polish attack'. They used this as Propaganda to pave the way for Germany to invade Poland the next day. Within a few days, Britain declared war on Germany.
The united states watched WW2 on fold. President Roosevelt wanted to help the Allies, though most Americans did not want to join in on the war. He asked Congress to allow France and Britain to buy American Weapons. So, American ships were escorting British ships carrying guns bought from the U.S. By fall 1941, U.S. ships had the orders to fire on German submarines that threatened the ships. The U.S. and Germany were fighting an undeclared naval war.
The Allied Side: Great Britain, Canada, Australia, South Africa, France (surrendered June 1940), Poland (surrendered october 1939), New Zealand, India, Belgium (surrendered May 1940), Holland (surrendered May 1940), Norway (surrendered March 1940) and Greece (surrendered April 1941), also to a small degree nationlist China but was only at war with Japan and was never foramally a part of the western alliance- U.S entered December 1941
Axis- Germany, Italy, Japan (not at war with Britain and the other allies till December 7th), Romania, Hungary, Bulgeria, Finland and Slovakia
Communist- Soviet Union (sort of allied to Britain and the other allied nations but with a degree of independence due to ideolistic differences) and Communist China (only at war with Japan)
Before world war 2, Spain was involved in a civil war.
The United States had invaded the Philippines before they entered the World War 2.
The USA entered the war on December 7th 1941 with the bombing of Pearl harbour in Hawaii.
It wanted to stay isolated. It did not want to get involved into a 'European' affair. The German sinking of the Lusitania was a reason the U.S. entered Worl War I and the Japanese bombing of Pearl Harbor, Hawaii was the reason the U.S. entered World War II.
2 years
Before world war 2, Spain was involved in a civil war.
They entered because they wanted to EDIT: Czechoslovakia never entered World War II. It was annexed by Germany before the war began.
It was The US entered WW I on April 16th, 1917.
The United States entered the war after the bombing of Pearl Harbor.
France
the united states entered the war late on both world war 1 and world war 2 they involved most of the same countries they both affected the world greatly they both involved many countries the allied powers won both
The United States had invaded the Philippines before they entered the World War 2.
Probably top 3.
Enjoying life.
cigarettes
The USA entered the war on December 7th 1941 with the bombing of Pearl harbour in Hawaii.
The United States entered World War I on April 6, 1917, and remained in the war until it ended on November 11, 1918.