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Researching the Dambusters raid

John Sweetman is the author of the recently published book, The Dambusters Experience. Learn about his research into the history of Operation Chastise.

Writing to The New Statesman after the release of The Dam Busters film in 1955, Air Marshal Sir Robert Saundby complained that Barnes Wallis "invented the weapon ... but he did not originate the idea." Attacking the German dams had been conceived by the Air Staff pre-war. This was the starting point for my research.


The Moehne and Sorpe dams had, indeed, been identified as targets in 1937. A year later the 'Achilles' heel, whose destruction was of ‘"rgent and pressing importance", breach the dams and the loss of water in their reservoirs would severely affect, if not paralyse, armament production in the Ruhr.

Two years later, the seven dams on the draft operation order in 1943 were highlighted: five connected with the Ruhr industries and, further east, two with transport via the inland waterway system. Strenuous efforts were made to devise a means of destroying these targets, including torpedoes, rockets, a seaplane packed with explosives floated over the water, even a remotely-controlled drone. But guaranteed accuracy and a weapon of sufficient destructive power proved elusive, until Wallis devised his 'bouncing bomb' in 1942.

Test and trials

Official documents, though, lack the human dimension. My first port of call was Whitehill House, Effingham, where Sir Barnes Wallis allowed unfettered access to the multitude of papers, sketches and reports connected with his work. Through him, I met members of his staff and Bob Handasyde one of the test pilots, who explained their involvement in the lengthy series of tests and trials, from firing small shapes across Silvermere Lake, near Cobham to full-size drops of Upkeep (codename for Wallis’s unique weapon) off Reculver on the North Kent coast.

A.R. 'Dick' Collins a Road Research Laboratory scientist, who was in charge of the tests on scale models of the Moehne Dam at Garston and Harmondsworth, proved another mine of priceless information. Crucially, he calculated the amount of explosives to be detonated in contact with a dam. Sir Arthur Harris, Sir Ralph Cochrane and Air Commodore Harry Satterly, who composed the operation order, provided invaluable Service insights.

Many of survivors of the operation and members of their families, either in person or by correspondence, gave lengthy and often moving accounts of their experiences to complete the picture of this extraordinary operation. Nothing should deflect from the courage and professionalism of the crews on the night. Hans Rumpf, a high-ranking Nazi official, declared their achievement "precision bombing of a high order". Without Barnes Wallis, dubbed "our wizard boffin" by Harris, they would not have had the means to succeed.

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