Declarations of War

Austria against Belgium Aug. 28, 1914 Austria against Japan Aug. 27, 1914 Austria against Montenegro Aug. 9, 1914 Austria against Russia Aug. 6, 1914 Austria against Serbia July 28, 1914 Belgium against Germany Aug. 4, 1914 Brazil against Germany Oct. 26, 1917 Bulgaria against Rumania Sept. 1, 1916 Bulgaria against Serbia Oct. 14, 1915 China against Austria Aug. 14, 1917 China against Germany Aug. 14, 1917 Costa Rica against Germany May 23, 1918 Cuba against Austria Dec. 16, 1917 Cuba against Germany April 7, 1917 France against Austria Aug. 12, 1914 France against Bulgaria Oct. 16, 1915 France against Germany Aug. 3, 1914 France against Turkey Nov. 5, 1914 Germany against Belgium Aug. 4, 1914 Germany against France Aug. 3, 1914 Germany against Portugal March 9, 1916 Germany against Rumania Aug. 28, 1916 Germany against Russia Aug. 1, 1914 Great Britain against Austria Aug. 13, 1914 Great Britain against Bulgaria Oct. 15, 1915 Great Britain against Germany Aug. 4, 1914 Great Britain against Turkey Nov. 5, 1914 Greece against Bulgaria Nov. 28, 1916 (Provisional government) Greece against Bulgaria July 2, 1917 (Government of Alexander) Greece against Germany Nov. 28, 1916 (Provisional government) Greece against Germany July 2, 1917 (Government of Alexander) Guatemala against Germany April 21, 1918 Haiti against Germany July 15, 1918 Honduras against Germany July 19, 1918 Italy against Austria May 24, 1915 Italy against Bulgaria Oct. 19, 1915 Italy against Germany Aug. 28, 1916 Italy against Turkey Aug. 21, 1915 Japan against Germany Aug. 23, 1914 Liberia against Germany Aug. 4, 1917 Montenegro against Austria Aug. 8, 1914 Montenegro against Germany Aug. 9, 1914 Nicaraugua against Austria May 6, 1918 Nicaraugua against Germany May 6, 1918 Panama against Austria Dec. 10, 1917 Panama against Germany April 7, 1917 Portugal against Germany Nov. 23, 1914 (Resolution passed authorizing military intervention as ally of England) Portugal against Germany May 19, 1915 (Military aid granted)

Rumania against Austria Aug. 27, 1916 (Allies of Austria also consider it a declaration) Russia against Bulgaria Oct. 19, 1915 Russia against Germany Aug. 7, 1914 Russia against Turkey Nov. 3, 1914 San Marino against Austria May 24, 1915 Serbia against Bulgaria Oct. 16, 1915 Serbia against Germany Aug. 6, 1914 Serbia against Turkey Dec. 2, 1914 Siam against Austria July 22, 1917 Siam against Germany July 22, 1917 Turkey against Allies Nov. 11, 1914 Turkey against Rumania Aug. 29, 1916 United States against Germany April 6, 1917