There are a countless number of decisions made during World War II that helped shape and change the course of history. There were events starting from Japan's invasion of Manchuria to Hitler's invasion of Poland to the dropping of the Atomic bombs on Hiroshima and Nagasaki. Every decision made by every general and field marshal made up what we would come to know as World War II.
One event that turned out to be a turning point in the war was Japan's decision to bomb Pearl Harbor, and execution of the plan. This was a turning point because before the bombing, the U.S. was divided between the isolationists and the people who wanted to go to war. Through bombing Pearl Harbor, Japan had hoped to scare the U.S. out of joining the war, because some of them knew that the U.S.' economic might could readily crush their new empire.
Instead of scaring the U.S., the bombing unified a divided America against the Axis powers. FDR did not know whether or not he should ask congress to declare war before the bombing, because he was afraid that he would not have enough popular support. The Japanese bombing at Pearl Harbor made up his mind for him. After the U.S. entered the war, many knew that it would only be a matter of time before the Japanese, Italians, and Germans would concede defeat. The U.S. declaration of war against the axis powers was only the first wave in the change of tides in the war.
Another event that was a turning point in the war was the defeat of the Japanese at the Battle of Midway. At Midway, the Japanese hoped to take over the small U.S. base at Dutch Harbor in the Aleutian islands. To ready themselves for their...