to become influential in terms of Bomber Command tactics, took command of 5 Group in October 1943. Group HQ was moved to Morton Hall, at RAF Swinderby in November 1943, Using the Stabilizing Automatic Bomb Sight (SABS) and the Tallboy, 617 Sqn achieved a bombing error of only at the V Weapon launch site at Abbeville, during December 1943. During the lead-up to D-day, Cochrane was an advocate of low-level marking, to improve accuracy, and lobbied heavily to be allowed to prove the principle operationally. New systems of target-marking were developed as result and were tested by 617 Squadron – especially its commanding officer, Wing Commander Leonard Cheshire, using the de Havilland Mosquito and North American Mustang. (Cheshire was subsequently awarded the Victoria Cross and taken off active operations.) The special missions included attacks on the German battleship Tirpitz in late 1944 and the use of the Grand Slam against the strategically-important Bielefeld railway viaduct, in March 1945. 5 Group was disbanded on 15 December 1945. Notable raids First "thousand-bomber attack" on Cologne on 30 May 1942 (shared) "Dambuster" attack on the dams at the Möhne Reservoir, the Edersee and Sorpedam on 17 May 1943 (without backup) Operation Bellicose, the first ‘shuttle raid’ of the war, against rocket facilities near Lake Constance and shipping at La Spezia Naval Base via Tunisia, in June 1943. Operation Hydra against the Peenemünde Army Research Center on 17 August 1943 Attack on Königsberg, 29 August 1944 Attack on Braunschweig, 15 October 1944 (without backup) Attack on Heilbronn, 4 December 1944 (without backup) Attack on Dresden on 13 February 1945 (without backup on the first attack) Grand Slam attack on Schildesche viaduct near Bielefeld on 14 March 1945 (without backup) Attack on Würzburg, 16 March 1945 (shared) Attack on the oil refinery at Tønsberg in Southern Norway, the last raid by heavy bombers of Bomber Command in World War II. Commanders 1918 to 1919 1 April 1918 Lieutenant Colonel Frederick Halahan May 1918 Brigadier-General Charles Laverock Lambe 1937 to 1945 17 August 1937 Air Commodore William Bertram Callaway 11 September 1939 Air Vice-Marshal Arthur Travers Harris 22 November 1940 Air Vice-Marshal Norman Bottomley 12 May 1941 Air Vice-Marshal John Slessor 25 April 1942 Air Vice-Marshal Alec Coryton 28 February 1943 Air Vice-Marshal Ralph Cochrane 16 January 1945 Air Vice-Marshal Hugh Constantine See also List of Royal Air Force groups References Citations Bibliography External links RAF