German forces invaded Poland. Following the 1939 aerial Battle of the Heligoland Bight, Royal Air Force (RAF) attacks shifted to the cover of darkness, initiating the Defence of the Reich campaign. By mid-1940, Generalmajor (Brigadier General) Josef Kammhuber had established a night air defense system dubbed the Kammhuber Line. It consisted of a series of control sectors equipped with radars and searchlights and an associated night fighter. Each sector named a Himmelbett (canopy bed) would direct the night fighter into visual range with target bombers. In 1941, the Luftwaffe started equipping night fighters with airborne radar such as the Lichtenstein radar. This airborne radar did not come into general use until early 1942. Night fighter career In October 1942, Kraft was posted to II. Gruppe (2nd group) of Nachtjagdgeschwader 4 (NJG 4—4th Night Fighter Wing). In January 1943, he was again transferred then serving with II. Gruppe of Nachtjagdgeschwader 5 (NJG 5—5th Night Fighter Wing). Kraft claimed his first air victory on 27/28 August 1943, an Avro Lancaster bomber shot down west of Nuremberg For this, he was awarded the Iron Cross 2nd Class () on 1 September and the Iron Cross 1st Class () on 15 November. Kraft was promoted to Oberleutnant (first lieutenant) on 1 February 1944 and received the Honor Goblet of the Luftwaffe () on 31 March. In May, II. Gruppe was subordinated to Nachtjagdgeschwader 6 (NJG 6—6th Night Fighter Wing) and moved Hungary on the southern sector of the Eastern Front. He was awarded the German Cross in Gold () on 23 July 1944. By September 1944, his number of aerial victories had increased to 44 for which he received the Knight's Cross of the Iron Cross () on 30 September. In February and March 1945, he claimed his last aerial victories, increasing his total to 56. For which he was awarded the Knight's Cross of the Iron Cross with Oak Leaves () on 17 April, the 838th officer or soldier of the Wehrmacht so honored. At the end of war he was taken prisoner of war by British forces and was released in August 1945. Later life Following the Wiederbewaffnung (rearmament) of the Federal Republic of Germany, Kraft joined the German Air Force in 1956. From 1 October 1 to 31 March 1980, he commanded the Luftwaffenversorgungsregiment 2 and retired holding the rank of Oberst (colonel). Kraft died on 16 October 1994 in Fürstenfeldbruck.