Kingdom of Belgium Kingdom of Serbia France Russian Empire (until March 1917) British Empire Kingdom of Italy (from April 1915) Canada United States (from 1917) Kingdom of Montenegro Empire of Japan Portuguese Republic (from March 1916) Kingdom of Romania (August 1916-May 1918) Kingdom of Greece (from June 1917) Albania Brazil (from October 1917) Armenia (from May 1918) Czechoslovakia Finland (from October 1918r) Kingdom of Siam San Marino (from June 1915) China (from August 1917)
Austro-Hungarian Empire German Empire (including German colonial forces) Ottoman Empire Kingdom of Bulgaria
Russian SFSR Ukrainian SSR Revolutionary Insurrectionary Army of Ukraine
Central Powers (until 1918): Austro-Hungarian Empire German Empire (including German colonial forces) Ottoman Empire Allied Forces (from 1918): Czechoslovakia China Estonia Finland France Greece Kingdom of Italy Empire of Japan Latvia Lithuania Poland Kingdom of Romania Kingdom of Serbia United Kingdom Australia Canada United States
Weimar Republic
Bavarian Soviet Republic Spartacus League German Communist movements
Democratic Republic of Georgia
Ottoman Empire (1918 only) Russian SFSR (from April 1920) Turkish Revolutionaries (from April 1920)
Republic of Mountainous Armenia Nagorno-Karabakh rebels British Empire (1918 only) Centrocaspian Dictatorship (1918 only)
White Russia Latvia United Kingdom Ingria Ober Ost Finnish, Swedish and Danish volunteers
Estonian Commune Latvian SSR
Estonia Poland United Kingdom France
Latvian SSR
Baltic nobility
Lithuanian-Byelorussian SSR
British Empire Kingdom of Greece France Kingdom of Italy Democratic Republic of Armenia Ottoman Empire
India
Free State of Fiume
Ukrainian People's Republic
Ukrainian SSR
Czechoslovakia Kingdom of Romania France
Slovak Soviet Republic
French Syria
Spain
Fengtian clique
Turkish revolutionaries
Poland
British Empire
United States
Tribal supporters British Empire (from 1929)
Forces of Habibullah Ghazi
British Colonial Forces
Part of Chinese Civil War
Fatherland's Front
Kingdom of Italy Germany Portugal
International Brigades Soviet Union Mexico
Communist Party of China United States (from 1941) British Empire (from 1941)
Manchukuo
Empire of Japan
Mongolia
From 1939 Poland Australia France New Zealand British Empire Nepal Union of South Africa Canada Czechoslovakia (government-in-exile) From 1940 Norway Belgium Luxembourg Netherlands Free France Kingdom of Greece Kingdom of Yugoslavia From 1941 Soviet Union Panama Costa Rica Dominican Republic El Salvador Haiti Honduras Nicaragua United States Republic of China Guatemala Cuba Philippines From 1942 Indian Empire Mexico Brazil Ethiopia From 1943 Iraq Bolivia Colombia Iran Yugoslavia From 1944 Liberia Peru Kingdom of Italy (formerly a member of the Axis) Kingdom of Romania (formerly a member of the Axis) Bulgaria (formerly a member of the Axis) San Marino (formerly a member of the Axis) Albania 1945 Only Ecuador Paraguay Uruguay Venezuela Turkey Egypt Lebanon Syria Saudi Arabia Argentina Chile
Germany Kingdom of Italy Hungary (from 1940) Empire of Japan (from 1941) Bulgaria (1940-1944)
Kingdom of Romania (1941-1944) Non-Axis Co-belligerents: Manchukuo Mengjiang Finland (1941-1944) Kingdom of Iraq (1941 only) Thailand (1942-1945)
French Indochina
India Palestine
Germany Kingdom of Italy
United Kingdom