The Second Battle of the Marne marked the turning of the tide in World War I. It began with the last German offensive of the conflict and was quickly followed by the first allied offensive victory of 1918. The American Expeditionary Force with over 250,000 men fighting under overall French command played key roles both in the initial defense and the later advances. In the Second Battle of Marne with 30,000 killed and wounded, the United States started suffering casualties on the enormous scale usually associated with the battles of the Great War.