Who fought World War I?

The World War which started in August 1914 went on for 4 years to end November 1918. On one side were the two empires of Germany and Austria-Hungary, later joined by Bulgaria and Turkey. They were called the Central Powers. Against them were Allies-the Russian Empire to the east, the French to the west, the British and the Belgium. Later the Italy, the Japan, United States, and many smaller nations joined the Allies. Because so many countries were involved, it later came to be called a World War.

After four years, these nations that had started the war were weary and exhausted. More than ten million soldiers had been killed. By coming fresh into the struggle, the United States tipped the scale, and the Central powers collapsed in defeat.