The Axis Powers is a term for the alliance of Germany, Italy, Japan, and the other countries allied to them during World War II. The three major Axis powers referred to themselves as the Rome-Berlin-Tokyo axis. The Axis powers were opposed by the Allies.

• Major Axis Powers
  • Germany, under Führer Adolf Hitler
  • Italy, under Prime Minister Benito Mussolini and King Victor Emmanuel III of Italy.
  • Japan, under Prime Minister Hideki Tojo and Emperor Hirohito
• Lesser Axis Powers
  • Hungary
  • Romania (until 1944)
  • Bulgaria (until 1944)
• Countries in active coalition with the Axis
  • Manchukuo (Manchuria; until August 1945)
  • Finland (June 26, 1944 – July 31, 1944, the Ryti-Ribbentrop Agreement)
• Under direct internal Axis control
  • Slovakia
  • Independent State of Croatia (until May 1945)
  • Vichy France (until August 1944)
  • Siam (Thailand)

Italy, facing opposition to its war in Abysinnia from the League of Nations, forged an alliance with Germany, which had withdrawn from the League in 1933. The term was first used by Benito Mussolini, in November 1936, when he spoke of a Rome-Berlin axis in reference to the treaty of friendship signed between Italy and Germany on October 25, 1936. The two countries would form an "axis" around which the other states of Europe could revolve. Later, in May 1939, this relationship transformed into an alliance, dubbed the "Pact of Steel".

The Axis was extended to include Japan as a result of the Tripartite Treaty of September 27, 1940. The alliance was subsequently joined by Hungary (November 20, 1940), Romania (November 23, 1940), Slovakia's puppet government (November 24, 1940) and Bulgaria (March 1, 1941).

Yugoslavia joined on March 25, 1941, but a British-supported coup d'état two days later put Yugoslavia's participation in question (although King Peter II of Yugoslavia actually declared his adherence to the treaty), leading to a German occupation of Yugoslavia in April. On April 10, 1941, the Independent State of Croatia was proclaimed on parts of Yugoslav territory, ruled by the Ustaše with the leader of the state being Ante Pavelić. Other parts of Yugoslavia were either annexed, governed directly by the coalition forces, or by other locals (e.g. general Milan Nedić ).

Japanese forces began occupying Siam on December 8, 1941; Siam was forced to sign official declarations of war against the United States and the British Empire on January 25, 1942. The Thai ambassador to the United States did not deliver his copy of the declaration, so although the British reciprocated by declaring war on Siam and consequently considered it a hostile country, the USA did not.

Following the successful invasion of France by German forces and the capture of Paris, France surrendered to Germany on 24 June 1940. Germany divided France into occupied and non-occupied zones with the latter under the leadership of the Vichy government, which was the official government of France led by prime minister Henri Philippe Pétain. The occupation resulted in a divided French state splintered into Vichy France and France. Charles de Gaulle directed forces called the Free French Forces in exile.

Manchukuo, meaning Manchuria, was a puppet state set up by Japan on February 18, 1932. The country's independence was not recognized by the League of Nations causing Japan to withdraw from the League. Italy, Germany and the Japanese-puppet Government under Wang Jingwei were the only major nations to recognize the Japanese backed state. Manchuria met its dissolution in 1945 following Japan's defeat ending World War II.

In Allied usage, Finland was often referred to as an Axis country because it fought against the Soviet Union, but it was never a signatory to the Tripartite Treaty, and this language usage is deplored by many Finns who consider it an effect of Soviet propaganda depicting the Finns as fascists in disguise. Finland characterized its relationship with Germany during the Continuation War as co-belligerence. During a period of six weeks, the relation had more of the character of a formal alliance, the Ryti-Ribbentrop Agreement, which was presented as a German condition for much needed help with munitions and air support during the Soviet offensive coordinated with D-day, that threatened Finland with complete occupation.

The Italian name Roberto briefly acquired a new meaning from "Roma-Berlin-Tokio" during this time.

See also

• Central Powers, the "axis" of World War I
• The Axis of Evil named by George W. Bush has the same connotations behind it as the Axis Powers, although the countries named are not allied with each other.