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World War I Participants |
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In all, 32 nations were listed as combatants in World War I - some in name only, however. The seemingly disproportionate number of Allied nations is misleading. Germany's military and technological might enabled the Central Powers* to fight on nearly even terms for four years.
* NOTE: The Central Powers are indicated by the shaded areas in the table below.
Country | Date | Event |
Austria-Hungary | July 28, 1914 | Declared war on Serbia |
August 5, 1914 | Declared war on Russia | |
August 28, 1914 | Declared war on Belgium | |
March 15, 1916 | Declared war on Portugal | |
Belgium | August 3-4, 1914 | Invaded by Germany |
Bolivia | April 13, 1917 | Broke relations with Germany |
Brazil | April 11, 1917 | Broke relations with Germany |
October 26, 1917 | Declared war on Germany | |
Bulgaria | October 14, 1915 | Declared war on Serbia |
September 1, 1916 | Declared war on Romania | |
China | March 14, 1917 | Broke relations with German |
August 14, 1917 | Declared war on Germany | |
August 14, 1917 | Declared war on Austria-Hungary | |
Costa Rica | September 21, 1917 | Broke relations with Germany |
May 23, 1918 | Declared war on Germany | |
Cuba | April 7, 1917 | Declared war on Germany |
Ecuador | December 8, 1917 | Broke relations with Germany |
France | August 12, 1914 | Declared war on Austria-Hungary |
August 23, 1914 | Invaded by Germany | |
November 5, 1914 | Declared war on Turkey | |
October 16, 1915 | Declared war on Bulgaria | |
Germany | August 1, 1914 | Declared war on Russia |
August 3, 1914 | Declared war on France | |
August 4, 1914 | Declared war on Belgium | |
March 9, 1916 | Declared war on Portugal | |
Great Britain | August 4, 1914 | Declared war on Germany |
August 12, 1914 | Declared war on Austria-Hungary | |
November 5, 1914 | Declared war on Turkey | |
October 15, 1915 | Declared war on Bulgaria | |
Greece | June 27, 1917 | Declared war on Austria-Hungary, Bulgaria, Germany and Turkey |
Guatemala | April 23, 1918 | Declared war on Germany |
Haiti | July 12, 1918 | Declared war on Germany |
Honduras | July 19, 1918 | Declared war on Germany |
Italy | May 23, 1915 | Declared war on Austria-Hungary |
August 21, 1915 | Declared war on Turkey | |
October 19, 1915 | Declared war on Bulgaria | |
August 28, 1916 | Declared war on Germany | |
Japan | August 23, 1914 | Declared war on Germany |
August 25, 1914 | Declared war on Austria-Hungary | |
Liberia | August 4, 1914 | Declared war on Germany |
Montenegro | August 5, 1914 | Declared war on Austria-Hungary |
August 8, 1914 | Declared war on Germany | |
October 15, 1915 | Declared war on Bulgaria | |
Nicaragua | May 8, 1918 | Declared war on Germany and Austria-Hungary |
Panama | April 7, 1917 | Declared war on Germany |
December 10, 1917 | Declared war on Austria-Hungary | |
Peru | October 6, 1917 | Broke relations with Germany |
Portugal | March 9, 1916 | Object of German war declaration |
March 15, 1916 | Object of Austro-Hungarian war declaration | |
Romania | August 27, 1916 | Declared war on Austria-Hungary |
May 7, 1918 | Surrendered to Central Powers (Treaty of Bucharest) | |
November 10, 1918 | Resumed hostilities against Central Powers | |
Russia | November 2, 1914 | Declared war on Turkey |
October 19, 1915 | Declared war on Bulgaria | |
San Marino | June 3, 1915 | Declared war on Austria-Hungary |
Serbia | August 6, 1914 | Declared war on Germany |
November 2, 1914 | Declared war on Turkey | |
Siam | July 22, 1917 | Declared war on Germany and Austria-Hungary |
Turkey | August 30, 1916 | Declared war on Romania |
April 23, 1917 | Broke relations with the US | |
United States | April 6, 1917 | Declared war on Germany |
December 7, 1917 | Declared war on Austria-Hungary | |
Uruguay | October 7, 1917 | Broke relations with Germany |
See also World War I Timeline.
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