The United States Army Air Forces (USAAF) targeted the German aircraft industry on 17 August 1943 in the Schweinfurt–Regensburg mission. Two Boeing B-17 Flying Fortress bombers from the 4th Bombardment Wing had been forced to leave their formation on their way to Regensburg. The B-17 "Picklepuss" piloted by Captain Robert M. Knox from the 100th Bomb Group headed back to England when it came under attack by three Messerschmitt Bf 110 night fighters south of Aachen. Von Bonin, accompanied by "Oberleutnant" Walter Barte and "Leutnant" Hans Witzke had taken off from Sint-Truiden—Saint-Trond in the French pronunciation—to intercept any stragglers to and from the target area. Von Bonin shot down the B-17 on his first attack but one of his engines was also hit be the left waist gunner. While seven of the ten crew members of the B-17 were killed in action, von Bonin landed safely on one engine at Saint-Trond.