Caption: "U.S. Army Signalers at work during the battle for St. Mihiel. Good communications were essential in large operations of this kind." The Battle of Saint-Mihiel was a WWI battle fought from September 12-15, 1918, involving the American Expeditionary Forces and 48,000 French troops under the command of General John J. Pershing of the United States against German positions. The United States Army Air Service played a significant role in this action. This battle marked the first use of the terms "D-Day" and "H-Hour" by the Americans. It was one of the first U.S. solo offensives in WWI and the attack caught the Germans in the process of retreating. This meant that their artillery were out of place and the American attack proved more successful than expected. Their strong blow increased their stature in the eyes of the French and British forces.