The Countries Involved in World War 1

Only the main country in an empire or colonial group has been listed here; please use the link to see a full breakdown (all were involved in World War 1). This is designed to aid reference and should not be considered a slight on the nations involved. There is also an introduction and a list of all nations by continent.

• Because of the conflict's nature, not all of these countries existed at the start of the war, not all existed at the end and some are in both these categories.
• Where a nation was created by one belligerent out of another's land, either as an independent country or a colony/protectorate, it has been recognised.
• Where an agglomeration of countries was usually referred to by an umbrella name - such as the West Indies - the constituent nations have been indented.

Countries Involved:
Albania
Arabia
Austria-Hungary
Belgium and colonies
Brazil
Bulgaria
China
Costa Rica
Cuba
Czechoslovakia
Estonia
Finland
France and Empire
Great Britain and Empire
Germany and Empire
Greece
Guatemala
Haiti
Honduras
Italy and colonies
Japan
Latvia
Liberia
Lithuania
Luxembourg
Montenegro
Nicaragua
Panama
Persia
Philippines
Poland
Portugal and colonies
Romania
Russia
San Marino
Serbia
Siam
Turkey
Transcaucasia
Unites States of America