Schräge Musik was the name the Germans gave to upward-firing autocannons that the Luftwaffe mounted in night fighter aircraft.
Interior view of Messerschmitt Bf 110G-4 Schräge Musik installation: 1. MG FF/M 2. Main drums 3. Reserve drums 4. Pressurized container with pressure-reducing gear and stop valve 5. Spent cases container 6. FPD and FF (Radio installation) 7. Weapon mount 8. Weapon recoil dampener.
The Luftwaffe and the IJN’s air arm had their first victories with fighter-mounted upward-firing autocannons in May 1943.
The night fighters used this innovation to approach and attack Allied bombers from below—outside the bomber crew’s usual field of view. An attack by a Schräge Musik-equipped fighter was typically a complete surprise to the bomber crew, who only realized a fighter was close by when they came under fire. Particularly in the initial stage of operational use, until early 1944, Allied crews often attributed sudden fire from below to ground fire rather than a fighter.