What was World War II like?

It was the bloodiest, deadliest war the world had ever seen. More than 38 million people died, many of them innocent civilians. It also was the most destructive war in history. Fighting raged in many parts of the world. More than 50 nations took part in the war, which changed the world forever.
For Americans, World War II had a clear-cut purpose. People knew why they were fighting: to defeat tyranny. Most of Europe had been conquered by Nazi Germany, which was under the iron grip of dictator Adolf Hitler. The war in Europe began with Germany's invasion of Poland in 1939. Wherever the Nazis went, they waged a campaign of terror, mainly against Jews, but also against other minorities.
In Asia and the Pacific, Japanese armies invaded country after country, island after island. On December 7, 1941, Japanese planes bombed Pearl Harbor, Hawaii. The next day, the U.S. Congress declared war, taking the U.S. into World War II.