-
Great Britain
Allies Of Great Britain. Britain and Belgium had a treaty to support each other if they were attacked. in 1914, Germany attacked France by moving through Belgium. Britain told Germany to retreat. -
Untied States
United States in WWI. Although World War I began in 1914, the United States did not join the war until 1917. ... The additional firepower, resources, and soldiers of the U.S. helped to tip the balance of the war in favor of the Allies.