The Allies won World War I. The primary members of the Allies were the British Empire, France, Italy (after 1915) and the Russian Empire, although Russia pulled out before the end of the war. Japan, Greece, Belgium, Serbia, Montenegro, Romania and several other nations contributed to the Allied cause. The United States fought alongside Allied troops but never formally entered the alliance.
The Allied Powers defeated the Central Powers, whose major members were Germany, Austria-Hungary and the Ottoman Empire, along with Bulgaria. The war took place between 1914 and 1918 and resulted in the deaths of at least 10 million soldiers.