The main countries that fought in World War I were:
* Allied Powers:
* France
* United Kingdom
* Russian Empire (until 1917)
* Italy (from 1915)
* United States (from 1917)
* Japan (from 1914)
* Central Powers:
* Germany
* Austria-Hungary
* Ottoman Empire
* Bulgaria
World War II (1939-1945)
The main countries that fought in World War II were:
* Allied Powers:
* United States
* United Kingdom
* Soviet Union
* China
* France (until 1940)
* Poland (until 1939)
* Australia
* Canada
* New Zealand
* South Africa
* India
* Brazil (from 1942)
* Mexico (from 1942)
* Ethiopia (from 1941)
* Yugoslavia (from 1941)
* Czechoslovakia (from 1941)
* Greece (from 1941)
* Denmark (from 1945)
* Norway (from 1945)
* Belgium (from 1944)
* Luxembourg (from 1944)
* Netherlands (from 1944)
* Axis Powers:
* Germany
* Italy
* Japan
* Hungary (from 1941)
* Romania (from 1941)
* Bulgaria (from 1941)
* Finland (from 1940)
* Slovakia (from 1941)
* Croatia (from 1941)
* Vichy France (1940-1942)
* Thailand (from 1942)
* Burma (from 1943)
* Philippines (from 1942)
* Dutch East Indies (from 1942)
* Malaya (from 1942)
* Singapore (from 1942)
* Hong Kong (from 1941)
* Manchukuo (from 1932)
* Inner Mongolia (from 1939)