1943: 19 aircraft of 617 Squadron, specially formed from some of the most experienced crews in Bomber Command, took off in the evening for Operation Chastise - an attempt to attack the Ruhr dams using Barnes Wallis' novel "bouncing bomb" - codenamed Upkeep. The delivery of the weapon, designed to skip over defensive anti-torpedo nets in the reservoirs and come to rest against the dam walls, required precision low flying over water at only sixty feet at night. Of the 19 Lancasters, five crashed or were shot down en route to the target at low level. A sixth was badly damaged and had to return home, as did another aircraft which was unable to find a dam in misty weather. However, five crews led by Wing Commander Gibson successfully breached the Mohne Dam, in the face of significant anti-aircraft fire. Gibson, his own bomb already used, then led three other crews to the Eder Dam, which was also breached. Three more aircraft bombed the Sorpe and Schwelme Dams, but were unable to breach them. On the way home, a further three Lancasters were lost; a total of 8 out of 19, with 53 aircrew killed and three captured. Gibson was awarded the Victoria Cross. The two dams breached contained between them 370 million tons of water, and were important suppliers of water and hydro-electric power for the German industrial heartland. The long-term effects of the destruction and disruption caused by the huge floods have perhaps been exaggerated on occasion, but the raid was nevertheless recognised as a very significant achievement, despite the high losses.
With thanks to Mr FM for this post