Nachtjagdgeschwader 1 (NJG 1) was a German Luftwaffe night fighter-wing of World War II. NJG 1 was formed on 22 June 1940 and comprised four Gruppen (groups). NJG 1 was created as an air defence unit for the Defence of the Reich campaign; an aerial war waged by the Luftwaffe against the bombing of the German Reich by RAF Bomber Command and the United States Air Force. In 1941 airborne radar was introduced with radar operators, and standardised in 1942 and 1943. Consequently, a large number of German night fighter aces existed within NJG 1.