Today marks the 71st anniversary of Operation Chastise. Better known as the Dambusters raid, this attack on German dams was one of the greatest technical achievements of WWII.
The Ruhr area was Germany’s industrial heartland, providing hydro-electric energy and pure water for steel-making, alongside water for the canal transport system. It was absolutely key to the manufacture of Germany’s war munitions and the Dambusters raid aimed to cripple it by destroying the Moehne, Eder and Sorpe dams.
The purpose-built bomb was designed by Barnes Wallis and his Vickers team, in a bid to damage the German war effort. They created a barrel-shaped bomb that would bounce along the surface of water. With an accurate drop, the bomb could bypass the dam’s defences and explode against the dam.
BRE in Watford built a scale model of the Moehne dam in secluded woodland, to be used to figure out the weight of the explosives needed. The model was used for explosive testing in 1941 and was badly damaged, but is now intact after being repaired.
A series of subsequent tests were carried out at the Road Research Laboratory at Harmondsworth, using simplified versions of the model. Dr A R Collins concluded that a full-size dam could be breached using 3,400 kg of explosive, detonated 9m below the water level.
‘After me, the flood’
While the bomb was being prepared, a newly formed Royal Air Force squadron, No. 617, went into rigorous training. The attack called for such precision that they trained for both night flying and low-altitude flying.
Over two nights, the Dambusters breached both the Moehne and Eder dams – the largest in Europe – causing a catastrophic flooding of the Ruhr Valley in Germany, destroying two hydro-electric power plants and damaging others. The Sorpe dam sustained only minor damage. Every bridge for 30 miles below the Moehne dam was destroyed, and buildings were damaged 40 miles away. An estimated 1,600 people drowned. In the short term, businesses and homes lost electricity and it’s estimated that coal production dropped by some 400,000 tons, but the damage was quickly repaired.
Casualties for the British raid were high. Eight of the original 19 Lancaster bombers were damaged or shot down. Fifty-three of the 133 airmen who took part were killed, and three were captured.RAF No. 617 squadron remained together, though, and adopted the motto ‘Apres-moi, la deluge’ (‘After me, the flood’).