夜間戰鬥機
Despite the Germans having only a fledgling defence, most of Bomber Command's operations against Germany in 1940–1941 failed. In the second half of 1940 170 RAF bombers failed to return. Only 72 of these were due to growing German competence in night fighting; 42 were claimed by the Luftwaffe and 30 by AAA units. The rest simply ran out of fuel. Most of these cases were caused by poor navigation training in the pre-war era. RAF loss rates were twice those of the Luftwaffe during The Blitz in the period, July 1940 and June 1941. The night offensives were defeated by a force of less than 60 aircraft in 16 "Staffeln" (Squadrons). Night fighter defences claimed 421 RAF bombers in 1941.