Map of the World showing the participants in World War I. Those fighting on the side of the Triple Entente (at one point or another) are depicted in green, the Central Powers in orange, and neutral countries in grey.
This is a list of countries that participated in World War I, sorted by alphabetical order.
The Entente Powers[]
Note: The "Entente Powers" are also known as the Allies of World War I or the Allies.
Andorra
Belgium (Belgian colonial empire)
Brazil- Republic of China
- Costa Rica
- Cuba
- Czechoslovak Legions
- France (French colonial empire)
- Kingdom of Greece
- Guatemala
- Haiti
- Honduras
- Kingdom of Italy
- Japan
- Liberia
- Kingdom of Montenegro
- Nepal
- Nicaragua
- Panama
- Portugal (Portuguese colonial empire)
- Kingdom of Romania
- Russian Empire
- San Marino
- Kingdom of Serbia
- Siam (now Thailand)
- United Kingdom of Great Britain and Ireland (British Empire[1])
- Canada
- British India (now India, Bangladesh, Burma and Pakistan)
- Newfoundland
- Australia
- New Zealand
- Malta
- Union of South Africa
- Rhodesia (now Zimbabwe and Zambia), administered by the British South Africa Company
- British crown colonies
- United States
- Alaska
- Hawaii
- Philippines
- Puerto Rico
- Other unincorporated territories
The Central Powers[]
- Austria-Hungary (now Austria, Bosnia and Herzegovina, Croatia, Czech Republic, Hungary, parts of northeast Italy, northern Serbia, partially Poland, Romania, Slovakia, Slovenia and Ukraine)
- Azerbaijan (now Azerbaijan and Eastern Armenia)
- Kingdom of Bulgaria (now Bulgaria, partially Greece, partially Republic of Macedonia)
- Dervish State (now parts of Somalia)
- German Empire (German colonial empire, at the time the empire occupied Burundi, Cameroon, small parts of China, partially Gabon, Germany, Ghana, Marshall Islands, Federated States of Micronesia, Namibia, northeastern Nigeria, Palau, northern Papua New Guinea, partially Poland, Republic of the Congo, Rwanda, Samoa, mainland Tanzania, and Togo)
- Jabal Shammar (now most of Saudi Arabia, parts of Iraq and Jordan)
- Ottoman Empire (now Iraq, Israel, Jordan, Lebanon, partially Saudi Arabia, Syria, most of Turkey, and other territories it lost before the war.)
Neutral countries[]
- Afghanistan - received a German diplomatic mission trying to convince it to act against the British in India
- Argentina
- Bolivia
- Bhutan
- Chile
- Colombia
- Denmark - Denmark was terrorized by Germany leading to their entry on the Allied side near the end of the war.
- El Salvador
- Ethiopian Empire - received a German diplomatic mission trying to convince it to act against Italy, United Kingdom and France in East Africa
- Liechtenstein - Had a customs and monetary union with Austria-Hungary.
- Luxembourg - Never declared war on the Central Powers despite being invaded and occupied by Germany.
- Bogd Khaanate of Mongolia -
- / Mexico - Declined an alliance with Germany (see Zimmermann Telegram).
- Netherlands - An ally of the United Kingdom by treaty. Traded with both sides.
- Norway - Gave naval assistance to the United Kingdom.
- Paraguay
- Persia - Occupied by Turkish, British and Russian troops.
- Spain - Also treaty-bound ally to the United Kingdom.
- Sweden - Non-belligerent.
- Switzerland - Switzerland did declare a "state of siege".
- Venezuela - Supplied the Allies with oil.
Declarations of War[]
European military alliances prior to the war.
Allies and Central Powers, early August 1914.
Allies and Central Powers, mid 1918.
The following table shows the timeline of the several declarations of war among the belligerent powers. Entries on a yellow background show severed diplomatic relations only, not actual declarations of war.
| Date | Declarer | On |
|---|---|---|
| 1914 | ||
| July 28 |  Austria-Hungary
|
 Serbia
|
| August 1 |  Germany
|
 Russia
|
| August 3 | Germany
|
 France
|
| August 4 | Germany
|
 Belgium
|
 United Kingdom
|
Germany
| |
| August 5 |  Montenegro
|
Austria-Hungary
|
| August 6 | Austria-Hungary
|
Russia
|
| Serbia
|
Germany
| |
| August 9 | Montenegro
|
Germany
|
| August 11 | France
|
Austria-Hungary
|
| August 12 | United Kingdom
|
Austria-Hungary
|
| August 22 | Austria-Hungary
|
Belgium
|
| August 23 |  Japan
|
Germany
|
| August 25 | Japan
|
Austria-Hungary
|
| November 1 | Russia
|
 Ottoman Empire
|
| November 2 | Serbia
|
Ottoman Empire
|
| November 3 | Montenegro
|
Ottoman Empire
|
| November 5 | United Kingdom France
|
Ottoman Empire
|
| 1915 | ||
| May 23 |  Italy
|
Austria-Hungary
|
| June 3 |  San Marino
|
Austria-Hungary
|
| August 21 | Italy
|
Ottoman Empire
|
| October 14 |  Bulgaria
|
Serbia
|
| October 15 | United Kingdom Montenegro
|
Bulgaria
|
| October 16 | France
|
Bulgaria
|
| October 19 | Italy Russia
|
Bulgaria
|
| 1916 | ||
| March 9 | Germany
|
 Portugal
|
| March 15 | Austria-Hungary
|
Portugal
|
| August 27 |  Romania
|
Austria-Hungary
|
| Italy
|
Germany
| |
| August 28 | Germany
|
Romania
|
| August 30 | Ottoman Empire
|
Romania
|
| November 1 | Bulgaria
|
Romania
|
| 1917 | ||
| April 6 |  United States
|
Germany
|
| April 7 |  Cuba Panama
|
Germany
|
| April 10 | Bulgaria
|
United States
|
| April 13 |  Bolivia
|
Germany
|
| April 20 | Ottoman Empire
|
United States
|
| July 2 |  Greece
|
Germany Austria-Hungary Ottoman Empire Bulgaria
|
| July 22 |  Siam
|
Germany Austria-Hungary
|
| August 4 |  Liberia
|
Germany
|
| August 14 |  China
|
Germany Austria-Hungary
|
| October 6 |  Peru
|
Germany
|
| October 7 |  Uruguay
|
Germany
|
| October 26 |  Brazil
|
Germany
|
| December 7 | United States
|
Austria-Hungary
|
| December 7 |  Ecuador
|
Germany
|
| December 10 | Panama
|
Austria-Hungary
|
| December 16 | Cuba
|
Austria-Hungary
|
| 1918 | ||
| April 23 |  Guatemala
|
Germany
|
| May 8 |  Nicaragua
|
Germany Austria-Hungary
|
| May 23 |  Costa Rica
|
Germany
|
| July 12 |  Haiti
|
Germany
|
| July 19 |  Honduras
|
Germany
|
| November 10 | Romania
|
Germany
|
See also[]
References[]
Notes[]
- ^ The British Empire was the common term for the United Kingdom and its overseas possessions at this time. The term refers to the colonies it controlled, to the Indian Empire, which, while not officially designated a colony, was functionally indistinguishable from one, and the British Dominions - former colonies which were self-governing in most respects but whose foreign policy was controlled by London; Australia, Canada, Newfoundland, New Zealand and South Africa. At that time, the United Kingdom of Great Britain and Ireland also included the entire island of Ireland.
The original article can be found at Participants in World War I and the edit history here.