Throughout July 1943, large numbers of Lancasters participated in the devastating round-the-clock raids on the city of Hamburg during Air Chief Marshal Harris's "Operation Gomorrah". A particularly famous mission performed by the Lancaster was the mission flown 16–17 May 1943, codenamed Operation Chastise, to destroy the dams of the Ruhr Valley. The operation was carried out by 617 Squadron in modified Mk IIIs carrying special drum-shaped bouncing bombs, which had been designed by British engineer Barnes Wallis. The story of the operation was later made into a film, "The Dam Busters."