17 May 1943: RAF 617 Sqdn. Lancaster bombers destroyed two of three targeted Ruhr Valley dams using bombs and aiming devices made expressly for that purpose.

The bombs designed by Sir Barnes Wallis weighed 9,000 lbs., were cylindrical--more like a depth charge--and employed a hydrostatic fuse to detonate them below the water's surface.

The only aircraft capable of delivering the devices was the four-engine Avro Lancaster. The mission was given to 5 Group and Wing Cdr. Guy Gibson, a highly qualified pilot with 170 bombing and night fighter missions to his credit. Gibson selected 21 crews from throughout the group and assigned them to 617 Sqdn. for the mission. Preparations were intensive as the bombs had to be delivered from a height of 60 feet and a speed of 240 at a precise distance from the target. This required a special aiming device that incorporated two lights that would converge when the aircraft reached the reached the release point. The entire mission would be flown at low level so as to avoid radar detection and reduce exposure to antiaircraft fire.'

Two Lancasters struck powerlines en route to their targets and five more were shot down during the course of the mission. Four men in the downed bombers survived and 53 perished. Gibson was awarded the Victoria Cross for remaining in the target area in an effort to draw off antiaircraft fire. Five crewmen were awarded the Distinguished Service Order, 14 got the Distinguished Flying Cross, two received Conspicuous Gallantry Medals, and 12 were given the Distinguished Flying Medal.

Those who participated in the mission were ever after called “The Dambusters.”

For details of the operation, see: https://en.wikipedia.org/wiki/Operation_Chastise

ILLUSTRATIONS: (1) 617 Sqdn. crewmen prepare to board their Lancaster for the raid on the Ruhr dams. (2) 617 Sqdn. Lancasters fly over Holland en route to the Ruhr Dams. (3) Flt. Lt. "Dinghy" Young's 617 Sqdn. Lancaster clears the Möhne Dam seconds after releasing his bomb, which severely damaged it. (4) The bomb aimer's view aboard Flt. Lt. "Dinghy" Young's Lancaster before he released their deadly cargo. (5) Plt. Off. David Maltby pulls his 617 Sqdn. Lancaster up and away after breaching the Möhne Dam. (6) Flt. Lt. John Hopgood's 617 Sqdn. Lancaster explodes after its failed attack on the Möhne Dam. (7) Plt. Off. Les Knight's 617 Sqdn. Lancaster breaches the Eder dam. (8) Flt. Sgt. Ken Brown powers away after scoring a hit on the Sorpe Dam with his 617 Sqdn. Lancaster. (9) Flt. Sgt. Ken Brown's tail gunner shoots up a locomotive from their 617 Sqdn. Lancaster. (10) Flt. Sgt. W. C. Townsend jinks his 617 Sqdn. Lancaster in an effort to avoid being hit by German flak during the flight back to England.