<Tr> <Th_colspan="2"> Commanders </Th> </Tr> <Tr> <Th> Commander in Chief </Th> <Td> Gen. John J. Pershing </Td> </Tr> <P> The American Expeditionary Forces (A.E.F., A.E.F. or AEF) was a formation of the United States Army on the Western Front of World War I . The AEF was established on July 5, 1917, in France under the command of Gen. John J. Pershing . It fought alongside French Army, British Army, Canadian Army, and Australian Army units against the German Empire . A minority of the AEF troops also fought alongside Italian Army units in that same year against the Austro - Hungarian Army . The AEF helped the French Army on the Western Front during the Aisne Offensive (at the Battle of Château - Thierry and Battle of Belleau Wood) in the summer of 1918, and fought its major actions in the Battle of Saint - Mihiel and the Meuse - Argonne Offensive in the latter part of 1918 . </P> <P> President Woodrow Wilson initially planned to give command of the AEF to Gen. Frederick Funston, but after Funston's sudden death, Wilson appointed Major General John J. Pershing in May 1917, and Pershing remained in command for the entire war . Pershing insisted that American soldiers be well - trained before going to Europe . As a result, few troops arrived before January 1918 . In addition, Pershing insisted that the American force would not be used merely to fill gaps in the French and British armies, and he resisted European efforts to have U.S. troops deployed as individual replacements in decimated Allied units . This approach was not always well received by the western Allied leaders who distrusted the potential of an army lacking experience in large - scale warfare . In addition, the British Empire tried to bargain with its spare shipping to make the United States put its soldiers into British ranks . </P>

What was the american expeditionary force and who led it