Participants in World War I

  Allies (at one point or another)

  Central Powers

  Neutral countries

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 (declared war on Germany but played no part in the fighting)
• Armenia
• Arab Rebels
• Belgium (Belgian colonial empire)
• Brazil
• China
• Costa Rica
• Cuba
• Czechoslovak Legions
• Emirate of Nejd and Hasa
• France (French colonial empire)
• Greece
• Guatemala
• Haiti
• Honduras
• Italy (Italian Empire)
• Japan
• Liberia
• Montenegro
• Nepal
• New Hebrides (British-French condominium)
• Nicaragua
• Panama
• Portugal (Portuguese colonial empire)
• Romania
• Russia
  • Russian Republic
  • Russian SFSR until Treaty of Brest-Litovsk
• Serbia
• San Marino
• Siam (now Thailand)
• United Kingdom (British Empire)
  • Canada
  • India (now India, Bangladesh, Burma and Pakistan)
  • Newfoundland
  • Australia
  • New Zealand
  • Malta
  • South Africa
  • Rhodesia (now Zimbabwe and Zambia), administered by the British South Africa Company
  • British crown colonies
• United States
  • Alaska
  • Hawaii
  • Philippine Islands
  • Puerto Rico
  • Other unincorporated territories
• Non Independent ethnic groups: Armenians, Assyrians, Poles, Pontic Greeks

The Central Powers

• Austria-Hungary
• Azerbaijan Democratic Republic
• Bulgaria
• Banat Republic
• Duchy of Courland and Semigallia (satellite state)
• Dervish State
• Democratic Republic of Georgia
• Germany
  • German colonial empire
• Jabal Shammar
• Kingdom of Lithuania (satellite state)
• Ottoman Empire
• South African Republic
• Senussi
• Kingdom of Poland (satellite state)
• Sultanate of Darfur
• Ukrainian State

Neutral countries

• Afghanistan – received a German diplomatic mission trying to convince it to act against the British in India
• Principality of Albania – In political chaos since the beginning of the war, the country was occupied by both Central and Allied powers but never declared war on either side
• Argentina
• Bolivia
• Bhutan
• Chile
• Colombia
• Denmark
• Ecuador
• El Salvador
• Ethiopia – 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)
• Monaco
• The Netherlands (Dutch Empire) – An ally of the United Kingdom by treaty. Traded with both sides.
• Norway – Gave naval assistance to the United Kingdom.
• Paraguay
• Peru
• Iran – Civil dispute and Allied Campaign against Ottomans
• Spain (Spanish Territories in Africa)
• Spitsbergen – Danish-Norwegian co-dominium
• Sweden – Non-belligerent
• Switzerland – Switzerland did declare a "state of siege"
• Uruguay
• 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 Ottoman Empire
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

• Allies of World War I
• Triple Entente
• Triple Alliance
• Central Powers
• Participants in World War II

Notes and references

1. ^ 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.