No. 5 Group RAF effective squadrons of Bomber Command, personified by No 617 Squadron the "Dambusters", formed from 5 Group aircrew in March 1943. Most of the group's main airfields were around Lincoln, including RAF Scampton. By the end of the war the group had grown to 15 squadrons. The group was noted for its high accuracy bombing, being involved the sinking of the "Tirpitz" in November 1944 and the shattering of the strategic Bielefeld railway viaduct in March 1945. The Group introduced new weapons operationally, including Barnes Wallis's "bouncing" and his Tallboy and Grand Slam "earthquake" bombs. The group was disbanded on 15
No. 421 (Reconnaissance) Flight RAF No. 421 (Reconnaissance) Flight RAF No. 421 (Reconnaissance) Flight was a specialist RAF fighter flight created on 21 September 1940 to patrol the Channel and provide early warning of the types of incoming Luftwaffe raids from occupied France. It was later expanded to full squadron strength and renumbered as No. 91 Squadron on 11 January 1941. Its role led to its pilots being nicknamed "Jim Crows". In late September 1940, Air Chief Marshal Hugh Dowding was faced with two problems. The first was a change in Luftwaffe tactics. Until then the main daylight striking force had been the German bombers,