In France, the Air Service of the American Expeditionary Force, a separate entity under commanding General John J. Pershing that conducted the combat operations of U.S. military aviation, began field service in the spring of 1918. By the end of the war, the Air Service used 45 squadrons to cover 137 kilometers (85 miles) of front from Pont-à-Mousson to Sedan. 71 pursuit pilots were credited with shooting down five or more German aircraft while in American service. Overall the Air Service destroyed 756 enemy aircraft and 76 balloons in combat. 17 balloon companies also operated at the front, making 1,642 combat ascensions. 289 airplanes and 48 balloons were lost in battle.