The Dambusters 75 years on: How marbles inspired the Second World War's most daring bombing raid
This week marks the 75th anniversary of Operation Chastise, in which the Royal Air Force (RAF) secured a crucial victory at the height of the Second World War by dropping Barnes Wallis’s “bouncing bomb” on German dams.
The 19 Lancaster bombers of 617 Squadron, led by Wing Commander Guy Gibson, took out both the Mohne and Edersee dams to flood the Ruhr valley in North Rhine-Westphalia, Germany’s industrial heartland, destroying two hydroelectric power plants and damaging 125 armaments factories and several coal mines vital to the Nazi war effort.
Fifty-three British airmen lost their lives in the eight planes that were shot down or crashed during the surprise attack on the night of 16 May 1943, while approximately 1,600 civilians were killed – Allied prisoners of war and forced labourers among them. One of the targets, the Sorpe dam, sustained only a minor hit. The events of that night are nevertheless celebrated as one of the pivotal triumphs of the conflict.
Wallis’s innovation and the Lancaster’s huge bomb bay meant 9,000lb explosives could be skimmed along the surface of the river, to evade the submerged torpedo nets that guarded against underwater attacks as they spun en route to their target. The idea was derived from skipping marbles across a tub of still water in the inventor’s back garden in Surrey.
Tested on models in Watford and then on the disused Nant-y-Gro dam in Wales and at Chesil Beach in Dorset, Wallis’s idea encountered opposition from Ministry of Aircraft Production personnel who thought it too madcap and improbable to work before finally before being given the go-ahead by Air Chief Marshall Charles Portal, impressed by the trials.