The Jagdgeschwader 400 group was formed for the sole purpose of flying one of the world's most revolutionary aircraft - the rocket-powered Me 163. Although the Me 163 scored relatively few kills, giving it a success rate much lower than the Me 262, it still had a massive psychological impact upon the Allies, and the technology and experiences gained in the Me 163 went on to influence the jet fighters of modern times. The introduction of jet-powered aircraft demanded massive changes in training, equipment, servicing and tactics, all of which are described and examined in this essential analysis of the story of the Me 163 in frontline service with Erprobungskommando 16 and Jagdgeschwader 400.