Operation Chastise was an attack on
German dams carried out on 16–17 May 1943 by
Royal Air Force No. 617 Squadron, subsequently publicised as the "Dam Busters", using a specially developed "
bouncing bomb" invented and developed by Sir
Barnes Wallis. The
Möhne and
Edersee Dams were breached, causing catastrophic flooding of the
Ruhr valley and of villages in the
Eder valley; the
Sorpe dam sustained only minor damage. Two hydroelectric power stations were destroyed and several more were damaged. Factories and mines were also either damaged or destroyed. An estimated 1,600 civilians drowned: about 600 Germans and 1,000 mainly Soviet forced-labourers. The damage was mitigated by rapid repairs by the Germans, with production returning to normal in September.