World War II began on September 1, 1939, with Germany invading Poland. The United Kingdom and France declared war on Germany on September 3, 1939. On September 17, 1939, the Soviet Union joined the invasion of Poland. The Axis Powers opposed the Allied Powers.

Nazi Germany, Fascist Italy and the Empire of Japan were the Axis Powers. Führer Adolf Hitler, Germany’s dictator, and the Nazi Party, commanded the German forces. Benito Mussolini, Italy’s Prime Minister and dictator commanded the Italian forces, and Emperor Hirohito and Prime Minister Hideki Tojo commanded the Empire of Japan’s forces.

The Allied Powers were led by the United States, United Kingdom and the Soviet Union. Twenty-six other nations joined the Allies. President Franklin D. Roosevelt commanded the U.S. forces. Prime Minister Winston Churchill commanded the United Kingdom’s forces, and Joseph Stalin, the General Secretary of the Soviet Communist Party commanded the Soviet Union’s forces.

After World War I a number of restrictions were placed on Germany as a result of the Treaty of Versailles. The National Socialist German Workers Party governed Germany. It was known as the Nazi Party or the Third Reich.