No single achievement by Royal Air Force Bomber Command is collectively remembered as vividly as the raids on the Möhne, Edersee and Sorpe Dams on the night of 16th May 1943. The unit responsible - 617 Squadron - became known as "The Dambusters" and in May 2013 commemorated 70 years since the raid. Ben Montgomery reports from the Derwent Reservoir.
