"Lafayette, we are here" - The first U.S. troops arrive in France to fight alongside Britain and France against Germany in World War I

(Wikipedia) ... The first American troops, who were often called "Doughboys", first landed in Europe in June 1917. However the AEF did not participate at the front until late October 1917, when the 1st Division, a formation of experienced regular soldiers and the first division to arrive in France, entered the trenches near Nancy.
Pershing wanted an American force that could operate independently of the other Allies, but his vision could not be realized until adequately trained troops reached Europe. In order to rush as many troops as possible to France, the AEF left its heavy weapons behind and used French and British equipment. Continued