During his time with JG1, Otto Bach servedon 12, 4 and 5 Staffel. Around May 1943, he transferred to 5./JG1. He was appointed Staffelkapitän of 7./JG1 on 15 July 1944. On 26 November 1944, II./JG1 intercepted 1137 USAAF bombers attacking targets in the Ruhr area. The bombers were escorted by almost 700 fighters. Overwhelmed by superior numbers, Bach, then Staffelkapitän of 7th Staffel, was shot down and killed in combat with P-51 Mustangs over Stendal, Germany in Fw 190 A-9 (WNr 205186) yellow 15.