Barnes Wallis
Barnes Wallis was 53 years-old when WWII started. He had a gentle, slightly absent-minded face, as if he was always pre-occupied with scientific figures, which he probably was since he was an aircraft designer for Vickers, so people were surprised to learn that he was not just a genius, but also extremely persistent. Although Wallis had designed the most successful British dirigible and the Wellington bomber, as well as was currently designing its successor, the Warwick bomber, he was fascinated by bombs.

At that time, British bombs were both weak and extremely inaccurate because the budget for bomb production and research had been tiny during the interwar years. Production of new bombs had only started in 1938. None were larger than 500 lbs, and they were not very accurate. Both the Treasury and the upper levels of the Royal Air Force (RAF) were against the development of larger bombs because they would require larger planes, so the RAF only placed orders for 1,000lb bombs six months after the war started.

Convinced that well-designed factories and dams would only be scratched by small bombs, Wallis began to consider how to make more powerful bombs and the planes to carry them. Since his day job was dealing with problems related to the Warwick's tail, he did all of his research during his lunch hour and evenings, instead of spending time with his family. Wallis quickly decided that Germany's coal mines were too deep to be seriously damaged by bombs while oil fields were too far away. However, three huge German dams in the Ruhr Valley, the Moehne, the Eder, and the Sorpe, were worthwhile targets because they controlled the levels of the waterways that carried the endless flow of barges to the foundries in the Ruhr Valley. Destroying these dams would not only deprive the foundries of both power and water, but also wreck the transportation network of roads, bridges, and railways that supplied the German military machine with tanks, guns and planes. 500lb bombs were essentially useless against these dams since the base of the Moehne was 112 feet thick, while the Eder was even bigger.

Through his research, Wallis found that when a bomb was dropped in water the shockwave greatly magnified the power of the bomb. The advantage of such a bomb was that even if it missed, the resulting shockwave would most likely destroy the target or shatter its foundation.

When Wallis presented his designs to people in the RAF and the Ministry of Aircraft Production shortly after Dunkirk, the usual reaction was scepticism and/or derision, but Air Vice Marshal Arthur Tedder was interested. Pre-occupied with the practical demands of preparing for a German invasion, the decision-makers in the RAF naturally had little time or patience for revolutionary yet still theoretical ideas. However, Wallis survived an interview with the famously short-tempered Lord Beaverbrook, the Minister for Aircraft Production, and convinced him to consider diverting vital resources to developing two-ton and six-ton bombs that could be carried by existing bombers. The Blitz had started by this time, so bombing experts were interested in the idea of hitting Germany back.

When Tedder was assigned to be the head of the RAF in the Middle East Wallis lost his strongest supporter, and he learned that the key decision-makers in the British government did not understand his calculations, so they would prefer to rely on dropping many little bombs rather than a handful of huge bombs. Instead of giving up in frustration, he spent several months preparing a book-long 'note' explaining his theories in a manner that could be understood by laymen, and then sent the 'note' to roughly seventy influential men in science, politics and the military. The mass-market mailing approach produced results and he finally attracted the attention of the Ministry of Aircraft Production, which resulted in him making presentations to a series of committees.

A side-effect of the German bombing of English factories was that the people in charge of production had seen firsthand that 250lb or 500lb bombs, no matter how many, were still relatively ineffective since factories could be repaired and operational almost immediately after being bombed. He won permission to conduct tests on scale models but he found that in reality a 30-ton bomb would be required, which even he realized was impossible. Wallis seemed to have reached an impasse until he remembered watching his children skipping stones. He tested the basic theory in a tub outside his house that a bomb of only 9,500lb would do the job, if he could figure out how to control the dropping of a bomb so that it skipped correctly and impacted the dam.

Fortunately, Professor Patrick Blackett, head of an operational research branch, was interested in the idea and arranged for more advanced testing in a huge ship-testing tank hundreds of feet long. It took until mid-1942 to figure out that the missile needed to be shaped like a chubby barrel and dropped with a certain amount of backspin to ensure that it stayed on the same axis through its skips. However, solving the physical problems proved to be easier than persuading those officials with decision-making power to understand the potential of his theories. Wallis hit a polite, respectful, but unmoving wall until a chance encounter with a key official to discuss a different idea won him permission to build a half-dozen prototypes. He only needed the first two to fine tune the process and he had not used all six before he gave a presentation to a room full of admirals, who were not that interested in dams, but were bursting with excitement, as much as senior admirals can be, at the prospect of putting the German super-battleship, the Tirpitz, out of their misery.

After a great deal of behind the scenes maneuvering, Prime Minister Winston Churchill decided in February 1943 that the dams, not the Tirpitz, would be the first target. The mission had to launch in May to cause the greatest possible damage, so it was a tight deadline. When the project was suddenly cancelled eight days later, Wallis sank two airtight glass containers in the giant tank, and persuaded a trusting young woman to go in one of them and film the bomb smashing the other container. He then braved a meeting with Air Marshal 'Bomber' Harris, Chief of Bomber Command, that produced a Lancaster bomber for testing. Harris' support played an important role in pushing through against the entrenched bureaucracy, which despised the nonsense about the dams. The project was restarted and the race was on to produce working versions of the bombs in time for the mission. While the bombs were being produced, fighter planes took daily photos of the area around the dams to gain accurate measurements of rising water levels and to map out the anti-aircraft defenses.

Barnes Wallis was not the only man to realize that the shock waves of a bomb exploded underwater could destroy the dams. Oberburgermeister Dillgardt had figured out the basic theories and worried that the Allies would drop bombs on the dams, therefore they had to be strengthened. The military authorities responsible for the Ruhr Valley did not share his concerns and refused to provide the extra anti-aircraft batteries, smokescreens and searchlights that he politely and persistently requested.

The Dam Busters Raid
Formed specifically for the raid, 617 Squadron was made up of experienced crews that had finished their tours and had accepted another tour, giving up the six months of break from combat they had been promised. When squadron commander Guy Gibson was informed that his squadron would have to master low-level night flying, he requested Micky Martin, an expert in low-flying. Night after night the pilots practiced low-level flying. Gibson had never commanded a squadron before and had to learn the countless details needed to keep 21 bombers operational.

The first meeting between Gibson and Wallis was embarrassing since Wallis could not explain about the dams because Gibson's name was not on the tiny list of need-to-know, so Gibson only learned that he would drop a bomb that would create a shockwave.

A major setback occurred on April 15 when a test bomb broke apart after impacting the water and the second only bounced 100 yards. The bombs would either shatter or not bounce enough at 150 feet, so Gibson agreed to try flying at 60 feet, and the bomb worked perfectly at that height during a test run. Gauging height had been a key obstacle until the problem was solved by placing a spotlight under the nose and another one under the belly of the plane set to converge at 150 feet below the plane.

Sad that he could not take Nigger, his beloved black Labrador, with him on the operation, Gibson decided that the code word for success would be "Nigger." However, Nigger was run over and killed by a car the night before the raid.

The pilots and navigators only found out the target the night before the raid and spent the evening planning the best approaches. The dams were almost full with water when the raid happened. Any later and the dams would have started to release the water for farmers to water their crops.

The squadron was divided into three groups. Gibson led nine planes to attack the Moehne Dam, and any planes that still had bombs would continue on to the Eder. The second group consisted of five planes led by Joe McCarthy, and their target was the Sorpe. They were to approach the area from a different direction to distract the German defences. The remaining five planes were a mobile reserve.

While the pilots were in the air Wallis and Harris were pacing in the squadron's operations room. They would have been even more worried if they knew that two of the five planes intended for the Sorpe raid had been damaged by flak and had to turn back, while another two had been shot down, leaving only McCarthy. One of Gibson's planes simply disappeared on the way to the Moehne. Gibson made the first run but failed to destroy the dam. The second plane was blown up by by flak going in and blew up. It took two more runs before a bomb punched a hole in the dam and water poured through. After sending the code "Nigger," Gibson and the four planes that still had bombs moved onto the Eder.

Father Berkenkopf, the priest of a village located three kilometres down the valley, was awakened by the noise and rang his bell to warn the villagers to run for safety. It is unknown if any villagers actually survived but the priest was still ringing his bell when he died. A number of villages were wiped out by the water.

The layout of the valley made the Eder Dam a harder target and one plane was destroyed when it dropped its bomb too close, but the dam was broken as well.

McCarthy found himself having to deal with the Sorpe alone, but he managed to knock a big hole in the dam. Three planes in the mobile reserve were directed to the Sorpe, although one of the planes had disappeared. Mist prevented the other two from breaking the dam. The remaining two bombers were assigned to two smaller dams and one plane hit its target but the other plane was never heard from.

Coal mines fifty miles from the Moehne and from the Eder were flooded and factories and power stations had been demolished, while roads, bridges and railways had ceased to exist. 125 factories were destroyed and 1,294 people drowned, mostly Russian POWs.

Ten of the nineteen bombers had survived the raid. Distressed that 56 out of 133 men did not make it back, Wallis broke down crying while the rest of the pilots got drunk to celebrate success and survival. The crews received seven days of leave but Gibson spent two days personally writing letters of condolences to the next-of-kin.

On the train ride up to be formally presented to the King to receive their awards, the younger officers proceeded to get drunk and remove the pants of any officer who tried to interfere with their fun. Thanks to the strenuous efforts of the adjutant, the officers all made it to Buckingham Palace but they were in rough shape.

Post-Dambusters
Gibson was told that he had done enough missions and had to give up command to Squadron Leader George Holden.

The squadron was a victim of its success, no one wanted to waste it on unimportant targets but there were no more targets until Allied intelligence learned that Hitler was using slave-labor to construct blockhouses with walls sixteen feet thick and roofs twenty feet thick to protect the launching sites for V1 and V2 rockets. Unsure of exactly how much damage these rockets could cause to London, the War Cabinet decided to not find out, so they asked Wallis to explain his shock-wave bomb. Wallis replied that it would take months to develop six-ton and ten-ton bombs. Lancaster bombers had to be strengthened, new methods of casting had to be developed, and even the entire process of loading them onto the bombers required special trucks and winches.

While the new bombs were being prepared, the squadron launched a raid against the vital Dortmund-Ems Canal, losing a total of six planes and failing to destroy the canal. Holden died during the raid, so he was replaced by Martin, who focused on rebuilding the squadron. Many experienced pilots refused to serve in the squadron, believing it was a death sentence, even though only roughly one out of every ten crews survived a tour in regular squadrons.

Bomber Harris decided to make 617 Squadron a special operations squadron that would be trained to carry out accurate bombing, since the senior air force generals knew that night bombing was incredibly inaccurate. Although the Propaganda Department had successfully convinced people that British bombers were taking revenge for the Blitz, the raids actually did little if any damage. More important to Harris, the raids wasted the lives of bomber crews. The odds were that a squadron of twenty planes would lose every plane during a tour of thirty raids. Any survivors had six months of leave and then started over.

Accuracy would be improved with the introduction of the Stabilising Automatic Bomb Sight, which had a gyroscope. Martin was told that his pilots would have to be accurate within a hundred yards at 20,000 feet. The crews were trained in the use of the bomb sight by an officer with such a fanatical love of the bomb sight that he was physically incapable of discussing any other topic. The crews trained day and night for weeks until they could do it regularly. Whenever they had a free evening, most of the pilots would get drunk to relieve the pressure.

The site of the heavy rockets was demolished by 600 bombers following Gibson's master of ceremonies approach, which he had developed during the raid on the Moehne Dam, where one bomber flew low around the target while directing the bombing runs. Aware that he had failed to properly protect the site, Hitler's chief of night-fighters committed suicide.

Martin had only been intended as a temporary commander, so he was replaced by Wing Commander Leonard Chesire, who had accepted a drop in rank from group captain to command the squadron. Worried about Hitler's rocket launching sites, the War Cabinet decided that Wallis should stop working on the ten-ton bombs, although he won permission to continue with a lighter version of 12,000lbs, which was called Tallboy. The prototype Tallboys were 21 feet long and weighed 12,000 pounds. Designed to spin like a top, the bomb was incredibly accurate, and fell so fast that it broke the sound barrier.

The accuracy of night-bombing increased when the squadron finally developed a method of dropping flares on the target and then dive-bombing the target to ensure accuracy, instead of the traditional method of dropping bombs from higher altitudes. Dive-bombing with a four-engine Lancaster was not for the faint-hearted but the squadron's pilots were used to risks and they cratered several rocket launching sites. The squadron had become so accurate that it was able to bomb an air-engine factory in France without hitting the civilian houses nearby. A bomber had even buzzed the factory several times to give the workers time to evacuate the factory.

Despite failing three times to destroy a railroad bridge over a viaduct in Italy, 617 Squadron continued to perfect its bomb-dropping accuracy, and they made two runs on factories in France in early March, where they destroyed the factories without hitting any of the nearby civilian buildings. Incendiary bombs would be dropped to highlight the target for the bombers, and the squadron managed to demolish three workshops of a Michelin tire factory without touching the workers' canteen right next to the workshops.

In the space of a month, the squadron had dropped 473 tons of bombs without hitting any civilians. It is good that the squadron's pilots were continuing to improve their game because the Germans were building bomb-proof rocket and long-range gun bases. Unknown to the Allied leadership, the bases would also have long-range artillery with shafts that went 500 feet into the ground at 50 degree angles, but they did know that rockets from the bases could destroy London and make an invasion fail, so they had to be knocked out before the invasion started.

Squadron Commander Chesire realized that marking the target would be much easier in a Mosquito fighter than a Lancaster bomber. After practicing with the Mosquito, Chesire led an entire group of bombers, not just 617 Squadron, to flatten an aircraft factory near Toulouse on April 5. The fighter was able to dodge the flak and drop the markers on the exact spot without taking any damage from flak. On April 18, five Mosquitos marked the target for 6 Group against the railway yards near Paris, putting the yard out of operation until after the war. Several days later, the squadron's Mosquitos led one group of bombers, 200 planes, against railway yards at Munich. The Mosquitos marked the target, 617 dropped incendiaries and then the rest of group's planes dropped the real bombs, which transformed the railway yards into a cratered landscape. The technique was still new so one marker had been dropped near civilian houses, which had been destroyed but Chesire learned to drop fewer markers to avoid confusion. Bomber Harris was so pleased that he assigned 617 squadron to train a Mosquito squadron and two Pathfinder squadrons of Lancasters in their methods, so that 617 could go back to special operations.

Normandy Landings
617 Squadron set a new record in low-level flying when they fooled German radar into thinking that they were a convoy of ships heading to Calais in order to divert attention from the Normandy landings. The planes had to fly on one course for 35 seconds, turn, fly a reverse course for 32 seconds, and then turn back to the original course. For eight hours. The month of precision flying practice was so tedious that the crews seized any opportunity, no matter how hazardous, to blow off steam. Worried that the Germans might drop parachute troops on British airfields, Chesire had decided to issue the crews with pistols, Sten guns and grenades. Three days later, fed up with drunken target practice on the lawn near the mess and grenade-throwing competitions, he reclaimed the weapons. However, during the night of the invasion the squadron carried out the operation flawlessly, and the Germans believed that Calais was the target.

Two days after the invasion, 617 squadron had the opportunity to use the Tallboys to destroy a railway tunnel that would be used by a Panzer division to help stop the invasion. The bombs were not very exciting to watch explode because they simply burrowed deep into the ground, so the crews flew home disappointed. The next day, the recon photos showed that the bombs had produced craters 100 feet wide and 70 feet deep.

On June 14, the squadron, followed by 400 Lancasters, demolished the harbour sheltering dozens of E-boats that had preyed on the ships supplying the invasion. 617 dropped Tallboys, and the other bombers dropped 1,000lb bombs. The huge shockwave of water shattered the small boats, while several Tallboys destroyed the concrete pens meant to shelter the boats. The next night, they repeated the process on another E-boat base, sinking a total of 133 small ships.

However, the Germans had already started launching V1 rockets against London, and it seemed that the V2s would start soon, so 617 was told to hit the launching areas. Since the raids were carried out during daylight, the pilots were able to see the bombs in action for the first time. Bad weather stopped the squadron from hitting all of the sites, but they knocked out a storage area for rockets in a cave on July 4. The next day, they hit the cannon with 500 feet-long barrels sunk into the earth.

After the raid, Chesire, and his three flight commanders, David Shannon, Les Munro and Joe McCarthy, were taken off active duty. Chesire had flown 100 missions and long since should have been dead based on casualty rates. Wing Commander J. B. Tait took over 617. Despite hazy weather and murderous flak, the squadron destroyed the bomb-launching sites before Allied troops could reach them. 300 workers who thought that they were safe at the bottom of a shaft were entombed.

Harris wanted to destroy the U-boats pens in Germany that could resist even Tallboys, so Wallis was finally permitted to produce his ten-ton bombs.

Raids with Tallboys damaged the U-boat pens at Brest, which had concrete roofs sixteen-feet-thick, forcing the Germans to abandon the French ports.

The Tirpitz
While Wallis worked on his ten-ton bomb, Cochrane told Tait to sink the Tirpitz. It was too far to fly directly from Britain, so they flew to Russia on September 10. 617 was joined by 9 Squadron, which had become almost as accurate. The landing field in Russia was hard to find, and six bombers ended up as write-offs after landing in marshes. Several days were spent drinking vodka and battling bugs while the planes were repaired and the weather cleared. The two squadrons reached the Tirpitz but smoke machines quickly concealed the battleship, and none of the Tallboys hit the target. Worse, one plane did not return from the mission. Later, they learned that the Tirpitz had been badly damaged by one Tallboy Several nights later, 617 Squadron and 5 Squadron bombed the Dortmund-Ems Canal. The water drained from the damaged canal, trapping barges transporting vital war supplies such as coal and pre-fabricated U-boats.

617 and 5 Squadrons made another attempt to sink the Tirpitz, although the planes needed extra fuel tanks, and machine gun turrets were removed to reduce weight. Unexpected cloud cover meant that they were unable to hit the ship. However, the third time was the charm and several Tallboys hit the ship, causing it to keel over.

End of the War
The war was still going, so 617 squadron launched several raids against U-boat pens. The bombs did not completely penetrate the roofs, but their explosions brought down hundreds of tons of concrete that destroyed some U-boats and badly damaged more.

Meanwhile, the Grand Slam Bomb had finally been finished. 25-feet-long, it weighed 22,000lb. Tallboys had been dropped on the Bielefeld Viaduct, the key transportation link between the German army defending the Ruhr and the production centres in north-west Germany, but the narrow viaduct proved impossible to target accurately, even for 617 squadron, so the viaduct was surrounded by craters but still firmly rooted. When the Grand Slam Bomb was dropped near the viaduct, Wallis' theories were proven correct. Although dropped 30 metres from the viaduct, the bomb had burrowed roughly a hundred feet into the ground, and the resulting shockwave had caused the arches to vibrate to the cracking point, while the explosion had produced a giant cavity that destroyed the foundation of the arches, so that a hundred metres of arches simply collapsed.

617 carried out several raids on bridges with Tallboys and Grand Slams. One by one, every bridge crossing the Ruhr was destroyed. With the bridges eliminated, 617 returned to hitting U-boat pens. The pen at Farge was the largest concrete structure in the world with a roof twenty-three-feet-thick, but on March 27 two Grand Slams burst through the roof and several Tallboys damaged the pen so badly that it could not be used. The construction of the pen had required two years and the labour of 7,000 slaves, but it was destroyed in a matter of minutes.

Although most bombing missions were not bothered by enemy fighters, flak still took a toll of the planes, and planes were occasionally lost, while planes often returned home badly damaged. 617's last mission was an attempt to destroy Eagle's Nest and kill Hitler. Unknown to the squadron, he was in Berlin at the time. The target was concealed by a heavy snowfall, but the squadron demolished the barracks of Hitler's SS bodyguard.

Actually, 617 and another squadron were supposed to drop Tall Boys and Grand Slams on the bridges connecting Kyushu with Honshu to assist the American invasion of Japan, which was planned for January 1946, but the Japanese had surrendered by then.

Related Movies:
The Dam Busters (1955)
Directed by Michael Anderson, starring Michael Redgrave and Richard Todd
Faced with the need to destroy massive German dams during WWII, British inventor Barnes Wallis designs bombs that skip along the water. (please click here to read the review)

Further Reading:
The Dam Busters-Paul Brickhill, Pan Books: London, 1983.

It is an excellent book, which presents Wallis' dogged determination, and the desperate struggle to invent new, more powerful bombs, as well as the need to develop new methods of aiming and delivering the bombs. Brickhill's brief character sketches achieve the impressive feat of making the key players, basically Wallis, Cochrane, and the various squadron commanders, come to life. He does not hesitate to show the many bureaucratic obstacles that had to be overcome and the pilots' heavy drinking, both of which were probably less accepted at the time than they are now. My sole complaint is Brickhill's refusal to provide dates. Everything is a few days later or soon after, so that it becomes difficult to keep track of which month he is referring to, never mind which year.


Share this page with others: