Allied Powers:
- Belgium
- British Empire
- France
- Greece (from 1917)
- Italy (from 1915)
- Japan
- Montenegro
- Portugal
- Russian Empire (until 1918)
- Romania (from 1916)
- Serbia
- United States (from 1917)
Central Powers:
- Austro-Hungarian Empire
- Bulgaria (from 1915)
- German Empire
- Ottoman Empire