See main article: Participants of World War II
Axis Powers (signers of the Tripartite Treaty)
Co-signatories of the Tripartite Treaty
Countries that were annexed by, or at war with, Axis Powers before World War II
Allied Powers/Allied Forces
Countries that were attacked, occupied, or switched sides during the war
(Most countries below had declared their neutrality before being assaulted. Note that countries already listed above are not listed here)
- Albania (occupied by Italy April 7th 1939, by Germany September 26th 1943)
- Belgium (invaded by Germany May 10th 1940)
- Czechoslovakia(1) (Bohemia and Moravia occupied by Germany March 15th 1939)
- Denmark (occupied by Germany April 9th 1940. Greenland stayed officially under Danish souvereignity, but was under American protection since April 9th 1941. The small Greenland Army was created to repel German invaders early 1943.)
- Estonia (annexed by the Soviet Union June 18th 1940, occupied by Germany September 5th 1941, re-annexed by the Soviet Union in 1944)
- Finland (attacked by the Soviet Union November 30th 1939 and June 26th 1941)
- Greece (invaded by Italy October 28th 1940, German occupation from April 6th 1941)
- Iceland (occupied by Britain May 10th 1940, by USA from July 1941)
- Iran (occupied by Britain and the Soviet Union, August 1941 to May 1946)
- Iraq (started with pro-Nazi PM, refusing military transit or base (treaty) rights to Britain, invaded by Britain 1941 to 1958)
- Latvia (annexed by the Soviet Union June 18th 1940, occupied by Germany June 25th 1941, re-annexed by the Soviet Union in 1944)
- Lithuania (annexed by the Soviet Union June 18th 1940, occupied by Germany June 22nd 1941, re-annexed by the Soviet Union in 1944)
- Luxembourg (invaded by Germany May 10th 1940)
- The Netherlands (invaded by Germany May 10th 1940)
- New Guinea (occupied by Japan, September 1942-August 1945)
- Norway (invaded by Germany April 9th 1940)
- Philippines (occupied by Japan, December 1941-June 1945)
- Syria (occupied by Free French and British, June 1940-April 1946)
- Thailand (Occupied by Japan, declared war on the United States and United Kingdom on January 25 1942)
- Tunisia (Used by Italian and German troops to attack Egypt. Later occupied by Allied forces)
Supporters of the Allies
Countries that remained nominally neutral
Notes:
- Slovakia proclaimed independence of Czechoslovakia on March 14th, 1939. Nazi German influence and Wehrmacht presence was considerable until the German occupation in September 1944. The rest of Czechoslovakia, the provinces Bohemia and Moravia, were occupied by Germany March 15th 1939, and proclaimed German protectorates. Czech nationals fought extensively on the Allied side.
- Egypt was technically neutral, but Cairo soon became a major military base for the British forces. This was because of a 1936 treaty which gave Britain the right to station troops on Egyptian soil in order to protect the Suez Canal.
- Yugoslavia began the war as a neutral but Yugoslavia's Regent signed the Tripartite Treaty on March 25th, 1941, and met an anti-Nazi coup d'état when he returned on March 27th. This led to German occupation from April 6th 1941.
- France surrendered to Germany on June 22nd 1940, and the Vichy government was installed, which cooperated with the Germans. However, substantial French forces escaped the German advance or switched sides and continued to fight on the Allied side as Free French.
- French colonies initially fought alongside their parent country. When France surrendered most recognized the Vichy government.
- A relatively unknown footnote to WW2. The Mexican Republic declared war on the axis powers after the oil tankers "Portero de Llano" and "Faja de Oro" were destroyed by German submarines. Mexico's 201st Expeditionary air force (under US command) participated in the bombing of Japanese targets in the Philippines and served as translators between US forces and Spanish-speaking Filipinos.