The Tripartite Pact, also called the Three-Power Pact, Axis Pact, Three-way Pact or Tripartite Treaty was a pact signed in Berlin, Germany on September 27, 1940, which set up the Axis Powers of World War II. At first September 27 of 1940, it was signed by three countries: Germany, Italy, and Japan.
And Hungary (November 20 of 1940), Romania (November 23 of 1940), Slovakia (November 24 of 1940), Bulgaria (March 1 of 1941), Yugoslavia (March 25 of 1941) and Croatia (April 10 of 1941) joined the pact by 1940/1941. This included some countries that were under Japanese control.
The countries signing the pact agreed that they would help one another for ten years in political, economic and military scope. They also said that if any country who signed the pact was attacked by another country which hadn't joined the war by then, excluding the Soviet Union, the country would face war from all countries who signed the pact.
Since 1943, the Tripartite Pact began to fall. Many countries were out of the war or changed to the Allies side. Although the pact remained in effect until Japan's surrender in August 1945, German defeat three months earlier made the pact little meaning.