The main Allied Powers in World War I were:

  • Great Britain (and the British Empire) , including dominions like Canada, Australia, New Zealand, South Africa, and India.
  • France , with its overseas colonies.
  • Russia , a key original member until its withdrawal after the 1917 revolutions.

Other major states that fought alongside them were:

  • Italy , which joined the Allies in 1915 after initially being part of the Triple Alliance with Germany and Austria-Hungary.
  • Japan , which entered the war against Germany in 1914 and seized German possessions in the Pacific and China.
  • The United States , which joined in 1917 as an “associated power,” fighting on the Allied side but not formally bound by all Allied treaties.

Many other countries also supported the Allies or associated with them, including Belgium, Serbia, Portugal, Romania, Greece, Brazil, China, and several Latin American and smaller states , contributing troops, resources, or diplomatic support.