Operation Chastise is undertaken by RAF Bomber Command with specially equipped Avro Lancasters to destroy the Mohne, Sorpe, and Eder dams in the Ruhr valley.

Operation Chastise, commonly known as the Dambusters Raid, was an attack on German dams carried out on the night of 16/17 May 1943 by 617 Squadron RAF Bomber Command, later called the Dam Busters, using special bouncing bombs developed by 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 damaged. Factories and mines were also damaged and destroyed. An estimated 1,600 civilians – about 600 Germans and 1,000 enslaved labourers, mainly Soviet – were killed by the flooding. Despite rapid repairs by the Germans, production did not return to normal until September. The RAF lost 56 aircrew, with 53 dead and three captured, amid losses of eight aircraft.

The Avro Lancaster, commonly known as the Lancaster Bomber, is a British Second World War heavy bomber. It was designed and manufactured by Avro as a contemporary of the Handley Page Halifax, both bombers having been developed to the same specification, as well as the Short Stirling, all three aircraft being four-engined heavy bombers adopted by the Royal Air Force (RAF) during the same era.

May 16 is the 136th day of the year in the Gregorian calendar; 229 days remain until the end of the year.