The Battle of Château-Thierry was fought on July 18, 1918 and was one of the first actions of the American Expeditionary Forces (AEF) under General John J. Pershing. It was a battle in World War I as part of the Second Battle of the Marne, initially prompted by a German Spring Offensive. German and local actions at Château-Thierry recommenced on May 31 to July 22, 1918, against the AEF, an American Expeditionary Force, consisting of troops from both the United States Army and Marine Corps units. These units were the newest troops on the front in France and just barely out of training.