World War II History: Expert Guides and Resources

Japan's ambassadors delivered the first part of a final Japanese diplomatic note to U.S. Secretary of State Cordell Hull on December 6, 1941. On the morning of December 7, the final portion of the note arrived from Tokyo to the Japanese ambassadors. The note broke diplomatic relations with the U.S. and provided instructions to destroy the code machines in the Japanese embassy.

A number of people and events influenced the course and outcome of World War II. This helpful timeline of World War II (WWII) maps out those key figures and actions in the years surrounding the war.Examining the beginnings of World War IIOfficially, World War II began when Nazi Germany invaded Poland in September 1939 and the French and English declared war against Germany as a result of that invasion.

Officially, World War II began when Nazi Germany invaded Poland in September 1939 and the French and English declared war against Germany as a result of that invasion. But the war's beginnings came long before this invasion. World War II was the product of a lot of things coming together in just the wrong way at just the wrong time.

The admirals in both the American and Japanese navies had grown up believing that the decisive naval action in the Pacific would be one straight out of the age of sail — two big battle fleets fighting within sight of each other, with the heavily armored and armed battleship providing the decisive edge. For nearly a generation, the war plans of both nations had envisaged such an engagement — that's why both Japan and the United States built big battleships and why the disarmament efforts of the 1920s focused on reducing the size and number of battleships in the world's fleets.

The years after World War II weren't peaceful. But they didn't erupt into World War III either (cross your fingers). For much of the time after World War II, the major world powers were preoccupied with a game of nuclear standoff. The major powers, by the way, turned out to be the United States and the Soviet Union.

Even before World War II began, scientists fleeing from Nazi Germany had warned U.S. officials the Germans were working on developing a huge new bomb that would be triggered through an atomic reaction. The U.S. government then began pouring what would amount to more than $2 billion into what would be called the “Manhattan Project.

Many African Americans had hoped their service in World War I would help bring them equality in post-war America. But they were wrong. So when World War II started, some black leaders were wary. Ultimately, African Americans did gain some ground in the civil rights movement through their involvement with World War II “Our war is not against the Hitler in Europe,” editorialized one black newspaper, “but against the Hitlers in America.

Despite all the warnings of war, the United States wasn’t completely prepared when World War II broke out. The Depression had rubbed out many of the country’s machine and tool industries, the military was woefully under-supplied, and many soldiers found themselves drilling with toy guns and wooden tanks. In a way, however, the Depression was a good preparation for what was to come: Americans had learned to scrimp and persevere.