Japan and China were already engaged in a military conflict before the outbreak of World War II. China was also involved in a civil war and spent most of World War II dealing with internal conflicts and repelling the advances of the Japanese.

Lasting from 1939 to the defeat of Nazi Germany in 1945, the Battle of the Atlantic was the longest continuous campaign of World War II. It pitted Nazi U-boats against North American convoys as Germany attempted to cut off Britain's vital lifeline to North America. The island nation was highly dependent on imported food and weapons. Although many ships were destroyed, the Allies gradually took control in the Battle of the Atlantic, enabling Britain to survive.

Formed from an empty munitions factory in March 1933, Dachau was the first Nazi concentration camp. According to a report made by the International Tracing Service at Arolson, Germany in 1977, there were 31,951 deaths at the main Dachau camp during its twelve year existence. Estimates for the number of deaths at Dachau, however, vary widely.

The Battle of Stalingrad was one of the bloodiest campaigns in human history. It was a blow from which the Axis powers never recovered and not only marked a turning point in the struggle to liberate the Soviet Union, but also contributed to the eventual defeat of a weakened Nazi Germany in 1945.

The Enola Gay, a B-29 Superfortress bomber piloted by Lt. Col. Paul Warfield Tibbets, Jr., was the plane that dropped the first atomic bomb on Hiroshima on August 6, 1945. A few days later, the Enola Gay flew reconnaissance as a support plane for the bombing of Nagasaki. For many years, the Enola Gay was displayed at the Smithsonian's Air and Space Museum in Washington, D.C.

With approximately 27 Million total fatalities (both military and civilian), the Soviet Union lost the most lives during World War II. China was next with approximately 11 Million total fatalities, followed by Germany with approximately 7 Million total fatalities.

On July 16, 1945, the Allied Manhattan Project successfully detonated an atomic bomb in the New Mexico desert and by August had produced atomic weapons based on two alternate designs.

Having risen to power with the support of Italy and Germany, the Franco government of Spain decided to send "volunteers" to aid Germany in its attack on the Soviet Union in the form of Division Azul (Blue Division). Spain, however, did not become directly involved in the war and remained a neutral power until the 1980s.

Operation Overlord was launched on 6 June 1944 with the Normandy landings. A 1,200-plane airborne assault preceded an amphibious assault involving more than 5,000 vessels. Nearly 160,000 troops crossed the English Channel on 6 June, and more than two million Allied troops were in France by the end of August.

Yamato and her sister ship, Musashi, were the largest battleships ever built. They were designed to counter the numerically superior battleship fleet of the United States, Japan's main rival in the Pacific.