Declarations of War: World War One

Austria - Hungary

1.28th July 1914: Serbia
2. 5th August 1914: Montenegro
3. 6th August 1914: Russia
4. 11th August 1914: France
5. 12th August 1914: United Kingdom
6. 22nd August 1914: Belgium
7. 25th August 1914: Japan
8. 23rd May 1915: Italy
9. 3rd June 1915: San Marino
10.15th March 1916: Portugal
11. 27th August 1916: Romania
12. 2nd July 1917: Greece
13. 22nd July 1917: Siam
14. 14th August 1917: China
15. 7th December 1917: United States
16. 10th December 1917: Panama
17. 16th December 1917: Cuba
18. 8th May 1918: Nicaragua

Serbia

1. 28th July 1914: Austria-Hungary
2. 6th August 1914: Germany
3. 2nd November 1914: Ottoman Empire
4. 14th October 1914: Bulgaria

Germany

1. 1st August 1914: Russia
2. 3rd August 1914: France
3. 4th August 1914: Belgium
4. 4th August 1914: United Kingdom
5. 6th August 1914: Serbia
6 .9th August 1914: Montenegro
7. 23rd August 1914: Japan
8. 9th March 1916: Portugal
9. 27th August 1916: Italy
10. 28th August 1916: Romania
11. 6th April 1917: United States
12. 7th April 1917: Cuba
13. 7th April 1917: Panama
14. 13th April 1917: Bolivia
15. 2nd July 1917: Greece
16. 22nd July 1917: Siam
17. 6th October 1917: Peru
18. 7th October 1917: Uruguay
19. 26th October 1917: Brazil
20. 7th December 1917: Ecuador
21. 23rd April 1918: Guatemala
22. 8th May 1918: Nicaragua
23. 23rd May 1918: Costa Rica
24. 12th July 1918: Haiti
25. 19th July 1918: Honduras
26. 10th November 1918: Romania

Russia

1. 1st August 1914: Germany
2. 6th August 1914: Austria-Hungary
3. 1st November 1914: Ottoman Empire
4.19th October 1915: Bulgaria

France

1. 3rd August 1914: Germany
2. 11th August 1914: Austria - Hungary
3. 5th November 1914: Ottoman Empire
4. 16th October 1915: Bulgaria

 Belgium

1. 4th August 1914: Germany
2. 22nd August 1914: Austria-Hungary

United Kingdom

1. 4th August 1914: Germany
2. 12th August 1914: Austria-Hungary
3. 5th November 1914: Ottoman Empire
4. 15th October 1915: Bulgaria

Ottoman Empire

1. 1st November 1914: Russia
2. 2nd November 1914: Serbia
3. 3rd November 1914: Montengro
4. 5th November 1914: United Kingdom
5. 5th November 1914: France
6. 21st August 1915: Italy
7. 30th August 1916: Romania
8. 2nd July 1917: Greece
9. 22nd July 1917: Siam

Italy

1. 23rd May 1916: Austria-Hungary
2. 21st August 1916: Ottoman Empire
3. 19th October 1916: Bulgaria
4. 27th August 1917: Germany

Bulgaria

1. 14th October 1916: Serbia
2. 15th October 1916: United Kingdom
3. 15th October 1916: Montengro
4. 16th October 1916: France
5. 19th October 1916: Russia
6. 19th October 1916: Italy
7. 10th April 1917: United States
8. 2nd July 1917: Greece

United States

1. 6th April 1917: Germany
2. 10th April 1917: Bulgaria
3. 20th April 1917: Ottoman Empire
4. 7th December 1917: Austria-Hungary

Countries that Declared War on Germany, Austria-Hungary, Ottoman Empire and Bulgaria

1. Serbia
2. Russia
3. France
4. United Kingdom
5. Montenegro
6. Italy
7. Romania
8. United States
9. Greece

Countries that Declared War only with Germany

1. Bolivia
2. Liberia
3. Peru
4. Uruguay
5. Brazil
6. Ecuador
7. Guatamala
8. Costa Rica
9. Haiti
10. Honduras

Countries that Declared War with Germany and Austria - Hungary

1. Belgium
2. Japan
3. Portugal
4. Cuba
5. Panama
6. China
7. Nicaragua

Countries that Declared War with Germany, Austria-Hungary and the Ottoman Empire

1. Siam