Axis Alliance
World War II involved most of the world's nations. The war was fought chiefly between two major alliances: the Axis and the Allies. The Tripartite Pact of September 27, 1940, allied Germany, Italy, and Japan and became known as the Berlin-Rome-Tokyo Axis, or Axis alliance. These three countries recognized German hegemony over most of continental Europe; Italian hegemony over the Mediterranean; and Japanese hegemony over East Asia and the Pacific.
During World War II, the Axis came to include Slovakia (November 1940), Hungary (November 1940), Romania (November 1940), and Bulgaria (March 1941). Finland fought with Germany against the Soviet Union but did not sign the Tripartite Pact and was not technically part of the Axis alliance. Yugoslavia joined the Axis alliance on March 25, 1941, but withdrew two days later after an anti-German coup. After Germany and its allies invaded and partitioned Yugoslavia, the newly established fascist satellite state of Croatia joined the Axis on June 15, 1941. Although an anti-democratic state sympathetic to the Axis, Spain refused either to join the Axis alliance or to enter the war with the Allies.
World War II began in Europe with the German invasion of Poland on September 1, 1939. Great Britain and France--which had agreed to defend Poland in case of attack--in response declared war on Germany on September 3. Italy entered the war on June 10, 1940. Japan, at war in Asia since the 1930s, expanded the conflict with a surprise attack on the American fleet on December 7, 1941, at Pearl Harbor in Hawaii.
The Axis was defeated in the course of World War II. Italy signed an armistice with the Allies in September 1943. Germany surrendered unconditionally to the Allies in May 1945, as did Japan in September 1945.