The American Expeditionary Force (AEF) was created in the summer of 1917, and by the spring of 1918 more than a million American soldiers were already stationed in France. The expeditionary forces consisted of infantry divisions and marines.
Commanded by General John Joseph Pershing, American soldiers fought alongside units from the French, British, Canadian, New Zealand and Australian armies. Pershing wanted the AEF to be able to act independently, without the help of the Allies, and eventually, when the training and combat experience of American soldiers reached the required level, it became possible.
US losses in this war was more than 320,000 killed and wounded American soldiers. Nevertheless, by the time the war ended in November 1918, the U.S. Expeditionary Forces were a fairly modern and battle-hardened army with a high level of motorization, and many considered it one of the best armies in the world.