This week is the 70th anniversary of the Dambusters raid, one of the most celebrated military operations of World War II but not very well known outside the UK. All week here in the UK there have been special documentaries about the attack, as well as news features, and showings of the 1955 movie. This afternoon my home city is celebrating with a special service at the cathedral and a flyover by a Lancaster bomber, the plane that performed so spectacularly in 1943.
The story of the Dambusters is familiar to almost every Brit but always worth retelling. During WWII, the German Ruhr Valley and its dams was identified as a strategic target. This was a heavily industrialised area and the dams supplied hydro-electric power, pure water for steel-making, and water to feed the canals–not to mention drinking water for the thousands of workers. It was calculated that repeatedly bombing the dams would breach them.
However, the degree of accuracy required was too much to maintain under enemy fire. A smaller explosive would work if it could be detonated below the surface of the water right beside the dam wall, but the dams were protected by heavy torpedo nets to prevent such an attack. Barnes Wallis (who was later knighted) had developed a bomb that when dropped from just the right height and at just the right speed, would skip across water for a significant distance in just the same way that children skip stones across a lake. The residual spin when the bomb finally reached the dam would cause it to run down the side of the bomb to its base under the water.
Trials were run on plaster models and a disused dam in Wales and were successful enough for 30 Lancaster Bombers to be assigned to the mission with just eight weeks to train.