Declarations of War.
The Nations Involved in the Great War
(from the Funk & Wagnalls New Encyclopaedia, 1983, Volume 27, p 418)
Austria-Hungary
Declared war on Serbia .........July 28, 1914
Declared war on Russia ........Aug 6, 1914
Declared war on Belgium ......Aug 28, 1914
Declared war on Portugal ......March 15, 1916
Belgium
Refused German ultimatum demanding permission for German troops to cross Belgium Aug 2, 1914
Invaded by Germany .........Aug 3-4, 1914
Bolivia
Severed relations with Germany ........April 13, 1917
Brazil
Severed relations with Germany .....April 11, 1917
Declared war on Germany .......Oct 26, 1917
Bulgaria
Declared war on Serbia .......Oct 14, 1915
Declared war on Romania ......Sept 1, 1916
China
Severed relations with German .....March 14, 1917
Declared war on Germany .....Aug 14, 1917
Declared war on Austria-Hungary ....Aug 14, 1917
Costa Rica
Severed relations with Germany ....Sept 21, 1917
Declared war on Germany ...May 23, 1918
Cuba
Declared war on Germany ....April 7, 1917
Ecuador
Severed relations with Germany ....Dec 8, 1917
France
Invaded by Germany ......Aug 2, 1914
Declared war on Austria-Hungary .....Aug 12, 1914
Declared war on Turkey ....Nov 5, 1914
Declared war on Bulgaria ....Oct 16, 1915
Germany
Declared war on Russia ....Aug 1, 1914
Declared war on France ....Aug 3, 1914
Declared war on Belgium ....Aug 4, 1914
Declared war on Portugal .....March 9, 1916
Great Britain
Declared war on Germany ....Aug 4, 1914
Declared war on Austria-Hungary ....Aug 12, 1914
Declared war on Turkey ....Nov 5, 1914
Declared war on Bulgaria ....Oct 15, 1915
Greece
Declared war on Austria-Hungary, Bulgaria, Germany and Turkey ....June 27, 1917
Guatemala
Declared war on Germany ....April 23, 1918
Haiti
Declared war on Germany ....July 12, 1918
Honduras
Declared war on Germany ....July 19, 1918
Italy
Declared war on Austria-Hungary .....May 23, 1915
Declared war on Turkey .....Aug 21, 1915
Declared war on Bulgaria .....Oct 19, 1915
Declared war on Germany ......Aug 28, 1916
Japan
Liberia
Montenegro
Nicaragua
Panama
Peru
Portugal
Romania
Russia
San Marino
Serbia
Siam
Turkey
US
Uruguay