On 25 March 1943, Munro, along with Flight Lieutenant Joe McCarthy and Squadron Leader David Maltby, were transferred to 617 Squadron to be part of the secretive Dambusters raid forming at RAF Scampton. The squadron was created to attack the dams of the Ruhr in an effort to wreck the industrial capacity of Germany. It was initially called Squadron "X", as the speed of its formation outstripped the RAF process for naming squadrons. Twenty-one bomber crews were selected from existing squadrons in 5 Group. These crews included RAF personnel of several different nationalities, as well as members of the Royal Australian Air Force (RAAF), Royal Canadian Air Force (RCAF) and Royal New Zealand Air Force (RNZAF), who were frequently attached to RAF squadrons under the British Commonwealth Air Training Plan.