Describe the major in the European Pacific Theater that either led to World War 2 or happened in the beginning of World War 2?

Answer 1

If you mean what caused the conflict in the Pacific Theater during World War II, well, that's easy.

The Japanese thought they got cheated during World War 1, because although they fought with the good guys (US, Britain, etc.), they gained much less territory from the German commonwealth (colonies). They only gained what is now North and South Korea.

So they needed more land to expand, so they attacked the Chinese colony of Manchuria, which the League of Nations (a sort of United Nations for after World War 1) strongly opposed. However, Japan eventually took control of most of eastern China and most of the Pacific Islands, which were either unoccupied or only had primitive natives living on them.

Now early in World War II, Japan was running out of supplies because the US and several other key production countries cut off supplies to Japan. Germany wasn't one of them, so the Japanese thought, "Hey, if we can make allies with Germany, we can get all these awesome weapons!" So Germany allowed Japan to join the Axis, along with Italy.

Now the main conflict of the Pacific was the US-Japanese conflict. All along with Europe being taken over by Germany and Italy, the US was like, "No! We won't join that bloody fight!" But when the Japanese attacked Pearl Harbor, which the US was furious of because Japan hadn't declared war. Anyway, the US declared war, and according to the Axis' alliance, Germany and Italy declared war on the US. So the US began a rapid assault on the Japanese-controlled Pacific Islands to win the war.