The Dambusters Raid of 1943

On the night of 16–17 May 1943, a squadron of the Royal Air Force conducted a daring mission deep into German territory to destroy two dams in the Ruhr valley, the industrial heartland of Germany. The subsequent flooding destroyed two hydroelectric power plants and several factories and mines, crippling Germany’s steel and coal production. The mission was codenamed Operation Chastise.

One of the targets, the Möhne dam in North Rhine-Westphalia, was the largest in Europe. It was built to help control floods and secure the water supply for much of the surrounding area. It was also used to generate hydropower. The British thought that the destruction of the dam and others in the Ruhr valley would cause massive disruption to German war production since the factories and industries in the valley relied heavily on power produced by these dams.

An illustration depicting Lancaster bombers attacking German dams during Operation Chastise. Photo: The National Archives UK/Wikimedia Commons

Germany knew that the reservoirs and dams were a weak spot in their defense, so they fiercely protected it with anti-aircraft guns and torpedo nets designed to catch any projectile released in the water and moving towards the dam wall. At first the British wanted to bomb the targets from above, but it would require an immensely large bomb to breach the dam. The same could be achieved with a smaller explosive charge if detonated against the dam wall under the water. If only there was a way to get past the torpedo nets.

Engineer Barnes Wallis came up with a solution—the bouncing bomb. Wallis devised a 4-ton bomb in the shape of a cylinder armed with a hydrostatic fuse, like in depth charges. The bomb was to be delivered by an aircraft travelling very low over the surface of the water. It was to be released with a backward spin that would cause the bomb to skip across the surface of the lake, avoiding torpedo nets, and hit the dam wall, whereupon it would sink and explode at the base of the dam. The spin would prevent the bomb from bouncing back after hitting the dam wall, and instead hug the wall surface causing maximum damage.

The attack plan. Photo: Imperial War Museum

A new squadron was formed for the mission, called No. 617 Squadron, later called the Dam Busters, led by 24-year-old Wing Commander Guy Gibson, a veteran of more than 170 bombing and night-fighter missions. His crew was made up of pilots from Britain, Canada, Australia, New Zealand and the USA, each with a lot of experience under their belt.

The RAF carried out extensive tests at sites across the country. The tests revealed that the drum-shaped bomb, codenamed “Upkeep”, needed to be dropped from a height of 60 feet and at a ground speed of 232mph, with a back-spin of 500 rpm. The delivery had to be precise, otherwise the bouncing bomb wouldn’t work. In the absence of modern technology, the RAF devised innovative solutions for each technical problem. To help determine the exact height, two spotlights were mounted under the aircrafts, one under the nose and the other under the fuselage, so that at the correct height their light beams converged on the surface of the water. To determine the exact moment of the drop, a special targeting device with strings and prongs was built.

The bouncing bomb being tested at Reculver bombing range, Kent. Photo: Imperial War Museum

On the night of 16 May 1943, 133 aircrew in 19 Lancasters took off in three waves for the three targets—the Möhne dam, the Eder dam and the Sorpe dam. The formations skillfully skirted German airbases and known flak positions, flying in and out of Germany before turning south to head for the Mohne river. To avoid radar detection, the bombers flew at only 100 feet. At one point, Flight Sergeant George Chalmers was astonished to see that his pilot was flying towards the target along a forest's firebreak, below treetop level.

It took five tries before the Möhne dam was breached. The attack left a huge hole in the dam, 77 meters across, through which floodwaters poured into the valley and swept away over a hundred factories and nearly a thousand houses, as well as dozens of roads, railways and bridges. The small city of Neheim-Hüsten was also hit with over 800 victims.

The Elder dam was not defended with anti-aircraft positions, but the topography was challenging, requiring the bombing crew to make multiple runs before they could get the angle of attack right. The dam was breached by a 70 meter wide hole, and the resulting flood inundated the valley as far as 30 km downstream.

The attack on Sorpe dam failed.

Eder Dam on the morning after the attack.

The breach in the Mohne Dam four hours after the Dambusters raid in May 1943. Photo: Flying Officer Jerry Fray RAF/Wikimedia Commons

The breach in the Mohne Dam four hours after the Dambusters raid in May 1943. Photo: Imperial War Museum

Möhne Dam after the attack. Photo: Schalber/Wikimedia Commons

The RAF flyers sustained heavy loses. Of the 19 bombers that took part in Operation Chastise, 8 were shot down and nearly half of the crew lost their lives.

It has been estimated that over 1,500 civilians lost their life, a large number of which were Russian prisoners of war held at a camp downstream from Möhne dam. With people perished thousands of cattle, pigs, horses and smaller animals like goats and sheep. The attack put an impressible dent on Germany’s coal and steel production, but the impact was not enough to change the course of the war. Steel production from Ruhr fell by a quarter, and coal production fell by 400,000 tons, mostly because the bombs knocked out the two hydroelectric power station plunging the region in darkness for two weeks. Both dams were repaired within months, and in the absence of follow-up raids to hamper reconstruction, Operation Chastise failed to bring about any long-term crisis the British War Ministry had hoped.

Wing Commander Guy Gibson with members of his crew. Photo: Imperial War Museum

The Möhne dam and reservoir today. Photo: Dominik Schäfer/Wikimedia Commons

References:
# The incredible story of the Dambusters raid, Imperial War Museum
# How successful was the Dambusters raid?, History Extra
# Wikipedia