World War I

Allied Powers

 * France
 * British Empire
 * Russian Empire
 * Roman Republic
 * Belgium
 * Serbia
 * Japan
 * Italy (From 1915)
 * Portugal (From 1916)
 * Brazil (From 1917)
 * Siam (From 1917)

Central Powers


 * German Empire
 * Austrian Empire
 * Wallachia
 * Kingdom of Hejaz and Nejd (From 1916)