a shortage of observers in that unit. Returning from a bombing raid on Saarbrücken, the aircraft in which Lt Thompson was operating the rear guns was attacked by German Albatross pursuit ships. He shot one down, becoming the first man in an American uniform to shoot down an enemy airplane. Later, on 28 July 1918, as a member of the 12th, he was credited with two more "kills." The 12th’s operations in the Toul Sector was a seasoning period for the squadron as it gained experience over a relatively inactive front with almost no enemy air opposition. "On the other hand," according to an Air Service report after the war, "the enemy antiaircraft fire in the sector was exceedingly dense, active and accurate. Pilots of the Group were adept at evading antiaircraft fire after a month in the sector." On 10 June, the 12th Aero Squadron moved to the Baccarat Sector and to the unfinished Flin Aerodrome, from which they supported the 42d American and 167th French Divisions. There, the 12th began to receive the latest in French observation aircraft, the Salmson 2A2. This front, too, was considered "stabilized" or quiet, but the opposing German air force, while not flying the latest types, was active and aggressive. The 12th flew visual and photographic reconnaissance, adjusted artillery fire, and staged "infantry-contact patrols" to locate the front lines. Battle of Château-Thierry By 29 June, the squadron had relocated to Saints Aerodrome in the Marne Sector to participate in the Battle of Château-Thierry. The 12th encountered intense opposition in the air from a concentration of German squadrons equipped with the most advanced Fokker aircraft. Encounters with up to 20 enemy aircraft on a patrol was a daily occurrence. On 5 July, the squadron moved again to a neighboring field at Francheville in support of the 26th Division, but because of its distance from the front, what would later be known as a "forward operating location," or FOL, was established at Ferme de Moras Aerodrome. Two 12th Squadron aircraft and two from the 88th Aero Squadron were flown to it at daybreak each day and held ready for developing requirements. The Allied counteroffensive was launched on 18 July and the squadron's support was vital in photographing targets ahead of the advance according to priorities set by corps intelligence. It was during this operation that oblique photography, sometimes from as low as 400 meters, began