How did World War 2 begin in Europe and why did the US enter the war?

Answer 1

The main cause of World War II in Europe was Adolf Hitler's invasion of Poland. When Hitler came to power, he immediately began expanding Germany into Austria and Chezhoslovakia. Before these two countries had been taken under German control, the larger European powers of Britain and France had employed a policy of appeasement, allowing Hitler to make whatever choices he felt would improve the state of affairs in Germany. However, after Czechoslovakia was invaded and taken under German control, this policy changed to one of deterrence, and Britain and France threatened to declare war if Hitler attempted to invade Poland and thus continue this kind of expansion. Thinking he would be calling their bluff, Hitler invaded Poland on September 1, 1939, and Great Britain declared war on Germany, setting the conflict that would eventually become World War II into motion.

Answer 2

They had no choice, because on 11th December 1941, Germany declared war on the US and started attacking US shipping in the Atlantic.

Answer 3

yes it did, and they entered the war to help Europe because they felt they needed to. I think they felt that if they helped at that time then at the time of need they would help them.