Poland: Invaded by Germany on September 1, 1939, sparking the outbreak of World War II.
Norway: Invaded by Germany on April 9, 1940.
Denmark: Invaded by Germany on April 9, 1940.
Belgium: Invaded by Germany on May 10, 1940.
Netherlands: Invaded by Germany on May 10, 1940.
Luxembourg: Invaded by Germany on May 10, 1940.
France: The French Third Republic collapsed after the military defeat to Germany on June 25, 1940.
Yugoslavia: Invaded by Germany, Italy, Hungary, and Bulgaria on April 6, 1941.
Greece: Invaded by Italy on October 28, 1940, and joined by Germany in April 1941.
British Malaya: Invaded by Japan on December 8, 1941.
Singapore: Captured by Japan on February 15, 1942.
Dutch East Indies: Invaded by Japan on January 11, 1942.
Philippines: Invaded by Japan on December 8, 1941.
Hong Kong: Captured by Japan on December 25, 1941.
Burma: Invaded by Japan on December 11, 1941.
Thailand: Became a de facto ally of Japan after their invasion of Malaya.
Italy: Surrendered to the Allies on September 8, 1943, after the Allied invasion of Sicily and mainland Italy.
Finland: Signed an armistice agreement with the Soviet Union on September 19, 1944, ending the Continuation War.
Romania: Overthrown by a pro-Allied coup on August 23, 1944, led by King Michael I.
Bulgaria: Declared war on Germany on September 5, 1944, after Romania's defection.
Hungary: Declared war on Germany on December 21, 1944, despite being occupied by German forces.
Germany: Surrendered unconditionally to the Allies on May 8, 1945, marking the end of World War II in Europe.
Japan: Surrendered to the Allies on August 15, 1945, following the atomic bombings of Hiroshima and Nagasaki.