Schräge Musik was the name the Germans gave to upward firing autocannons that the Luftwaffe mounted in night fighter aircraft. A similar fitment was used by the Imperial Japanese Army Air Service and Imperial Japanese Navy Air Service and known by a different, undocumented name in their twin-engined night fighters. The Luftwaffe and the IJN air arm had their first victories with fighter-mounted upward-firing autocannons in May 1943.
The term Schräge Musik derives from the contemporary German colloquialism for "jazz music".
Night fighters used this device to approach and attack Allied bombers from below, outside the bomber crew's usual field of view or fire. Most of the Allied bombers types of that era which were used for nocturnal bombing missions (primarily the Avro Lancaster) lacked effective ventral armament, leaving them easy prey to attacks from below, an advantage the Luftwaffe capitalized on. An attack by a Schräge Musik equipped fighter was typically a 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.