The British Air Ministry were not the only ones milling over the problems associated with attacking the dams.
Barnes Wallis, assistant chief designer at Vickers-Armstrong's Aviation Section quite independently (and for different reasons) came up with the idea of attacking the dams of the Ruhr Valley.
Dr Barnes Wallis
For a religious, family man described as a pacifist; working with weapons and machines of destruction seemed a very bizarre occupation. To Wallis the idea of taking life was one which appalled him. Why then, was this man a leading figure in not only the dambusters raid but also the whole allied war effort?
Before the war, Wallis was a aeronautical engineer and inventor who worked in many areas especially airship design and manufacture (See Barnes Wallis page for more information). Wallis saw his work as a deterrent to war and those who sought it, however when war broke out he saw there was a greater evil in Hitler and the Nazi movement and turned his mind to means in which to shorten the war and the suffering. It was this search for means to end the war as quickly as possible that led Wallis to the dams. He too, believed that attacking the energy sources of the German war machine would not only bring the war to an end more quickly but also cause less casualties on both sides than conventional targets.
It was Wallis who eventually solved the main problem associated with attacking the dams. Before we see how, what were the problems with attacking them?
Today even with modern sophisticated war equipment; laser guided cruise missiles and 'smart' bombs, a dam would be a difficult target to hit and breach. In the 1937 when the targets were first proposed this problem was even more difficult.
On the ground, a dam may seem a mighty structure that would be easy to hit from a large distance with a marble. However from a medium bombing altitude of 10,000 feet, the dam becomes a pin head in a field. Finding the dam would be very difficult never mind trying to hit it with any accuracy.
Finding the dams would be the bombers first problem. Just before the war, exercises showed that 40% of navigators could not find a nominated British city in broad daylight in peace times. A major problem! If you can't even find the dam, your chances of hitting it are zero. If you could find the dam, the second problem was hitting it. Exercises also showed that the average bombing error from 10,000 feet was more than 100 yards (30.5 meters). In war conditions it was expected that these figures would be even greater.
In actual fact, pre-war analysts had been greatly conservative in their estimates. In 1941 it was revealed that only about 10% of bombers sent to the Ruhr (to attack factory targets) actually reached their target area and only 33% (1 in 3) aircraft dropped its bombs within 5 miles (over 8,000 meters) of the planned impact area. Moreover, the planned impact area was defined as having a 5 mile radius. Basically, British bombers were dropping their bombs over an area of 75 square miles around the planned target. Given that the radius of Greater London is less than 25 miles and the length of the Mohne dam was 850 yards (777 meters) long and only 100 feet (30.5 meters) thick the chances of hitting a structure like this dam were at most 2%.
During the last 2 years of the war great advances were made in navigational and targeting technology, however at the time of the planned dams raid these did not yet exist and the only way to hit a dam with any accuracy would be to attack from low level which presents problems in itself.
The third problem was what weapon to use assuming you could (a) - find the dams and (b) - hit them. At the start of the war the standard RAF bomb was 500lb. These bombs would hardly make a scratch on a large, solid structure like a gravity dam which the Mohne and Eder both were. (The Sorpe dam was an earth dam). Bomber Command suggested dropping many of these 500lb bombs on the dam to saturate and destroy it. It was concluded however that over 750 - 500lb bombs would be required to even stand a 2% chance of breaching the dam. More probably in excess of 5,000 bombs would be required with almost perfect accuracy to break the great structures. This would require many thousands of sorties to the dams which the RAF simply could not sustain. It was clear that a larger bomb would be required if there was any real chance of success.
Problem four was finding a way to deliver the weapon to the targets assuming a big enough bomb could be built. In 1937 up until the beginning of 1942, the RAF did not possess an aircraft capable of carrying it into the industrial heartland of Germany. Twin engine aircraft which the RAF had in service such as the Armstrong Whitley, the Handley Page Hampden and the Vickers Wellington (which Barnes Wallis designed) were simply not up to this type of job. Alternative means of attacking the dams were discussed by the British including radio controlled aircraft packed with explosives, special torpedoes which could cut their way through the Germans defensive torpedo nets in front of the dams, missiles and even extreme options such as a raid by parachuting commandoes carrying sacks filled with dynamite.
As if these problems were not enough, when war broke out in 1939, the RAF had built up its bomber force believing that attacking in large numbers would allow the squadrons to fight their way into a target, bomb it and then get out. It was one of the biggest mistakes made by the British during the war. Just four days into the war during an attack on Wilhelmshaven, 23% of the bombers on the attack were destroyed. Three weeks later 45% of the aircraft involved in a raid over Heligoland were also shot down or destroyed. If the whole of the bomber force had been committed at once and had suffered similar losses, Bomber Command would have been totally wiped out within a matter of days! The heavy, slow RAF bombers were no match for the new, fast, well armed German fighters like the Messerschmitt Bf109. The defences of the bombers were totally inadequate. The RAF could no longer sustain losses like this and by the spring of 1940, the RAF stopped daylight bombing and began night time offensives. This inevitably made finding and hitting targets more difficult.
Assuming the problems above could be solved, the raid on the dams would have to be undertaken at low levels and during the night. It was hardly surprising that although the dams had been named as possible targets by the British in 1937 they were shelved due to problems in implementing the attacks...
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