The Allies of World War I or Entente Powers were the coalition of countries led by France, Britain, Russia, Italy and Japan against the Central Powers of Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria during the First World War (1914–1918).
By the end of the first decade of the 20th century, the major European powers were divided between the Triple Entente and the Triple Alliance.
The Triple Entente was made up of France, Britain, and Russia.
The Triple Alliance was originally composed of Germany, Austria–Hungary, and Italy, which remained neutral in 1914.
As the war progressed, each coalition added new members. Japan joined the Entente in 1914. After proclaiming its neutrality at the beginning of the war, Italy also joined the Entente in 1915.
The term “Allies” became more widely used than “Entente”, although the Principal Allies of France, Britain, Russia, Italy, and Japan were sometimes known also as Quintuple Entente.
The colonies and occupations of the countries of the allies were also part of the allied powers like British India (India, Myanmar [Burma], Bangladesh, Pakistan), French Indochina (Laos, Cambodia and Vietnam) and Japanese Korea (North and South Korea).
The United States joined in 1917 (the same year in which Russia withdrew from the conflict) as an “associated power” rather than an official ally.
Other “associated members” included Serbia, Belgium, Montenegro, Asir, Nejd and Hasa, Portugal, Romania, Hejaz, Panama, Cuba, Greece, China, Siam (now Thailand), Brazil, Armenia, Guatemala, Nicaragua, Costa Rica, Haiti, Liberia and Honduras.
The treaties signed at the Paris Peace Conference, 1919 recognized the United Kingdom, France, Italy, Japan and the United States as the ‘principal Allied powers’.