The famous “Dam Busters” raid conducted by the Royal Air Force (RAF) during the World War II was a major highlight of Allied air operations. A crucial personality behind the scenes was Barnes Wallis, a scientist, engineer and inventor who designed the unique bouncing bombs that breached Germany’s Möhne and Edersee dams, causing catastrophic flooding in the Ruhr valley and also damaged the Sorpe Dam.

Barnes Neville Wallis was born on September 26, 1887, in Derbyshire, England. At 17, he joined an engineering works as an apprentice. Meanwhile, he learned much of the theory needed for his career. In 1913 an opportunity arose for him to work on airship design and then aircraft design. He was an important figure in developing the airships of the 1920s and early 1930s. His key achievement was a geodesic structure for the Vicker’s R.100 airship that was later adapted for conventional aircraft. It gave planes a better chance of survival even after a direct hit from anti-aircraft fire.

In 1922, when the painfully shy Wallis was 35, he met his charming 17-year-old second cousin, Molly Bloxam. Her father first strictly forbade their friendship, but relented enough to permit them to correspond on the subject of mathematics, which Molly was grappling with for her university science course. During the next three years, the pair exchanged over 250 letters, with Wallis patiently explaining the intricacies of calculus and trigonometry, interspersed with more tender topics, and encouraging her to excel in mathematics. On Molly’s 20th birthday, Wallis mustered up enough courage to propose to her and they were married in April 1925.

When the World War II started in 1939, Wallis felt that the best option to defeat the Germans would be a strategic bombing campaign against their industrial heartland. Referring to their power supply facilities he wrote, “If their destruction or paralysis can be accomplished, they offer a means of rendering the enemy utterly incapable of continuing to prosecute the war.” The problem was the gross inaccuracy of high-level aerial bombing where less than ten per cent of bombs were expected to fall anywhere near their target. He began designing huge bombs of up to ten tonnes weight with enough explosive force to destroy large industrial targets that would otherwise not suffer greatly. Since the existing bombers could not carry such loads, he proposed a large plane which he called the “Victory Bomber”.

Hydroelectric dams were attractive targets mainly because they were massive fixed structures. However, Germany’s dams were well constructed and heavily defended. Any air raid would be immediately picked up on radar and neutralised by the German air defence. It was calculated that a huge amount of explosive power would be needed to breach a dam unless the explosion took place in contact with the wall. After mulling over the puzzle for some time, Wallis arrived at a solution which was to train a team of crack pilots to drop specially designed bombs with enhanced accuracy and send them in too low for radar detection.

Accordingly, he designed a bomb named ‘Upkeep’ that was powerful enough to break the concrete structure of a dam. After being released at ultra-low level some distance from target, the drum-shaped bomb would make a series of bounces on the water surface till it hit the dam, then roll down the dam’s wall and explode at its base. Upkeep was programmed to detonate only on sinking to a certain depth. It was also designed to lag well behind the dropping bomber to prevent the attacking aircraft being damaged by the force of the explosion below. Initial tests were rather discouraging, but Wallis quickly analysed the reasons and within months, was able to produce a bomb suitable for the intended mission.

“Operation Chastise” was mounted on the night of May 16/17, 1943, by 19 Lancaster bombers of No. 617 Squadron, led by Wing Commander Guy Gibson. Due to the breached dams, at least two hydroelectric power stations, 25 bridges and 11 factories were destroyed, plus significant damage inflicted on other industrial infrastructure. Casualties on the ground were around 1,300. The bomber fleet sustained heavy losses with eight aircraft shot down and 53 of the 56 aircrew killed. Although the hardworking Germans were able to eventually rebuild the facilities, the raid provided a huge morale boost to the Allied nations that were growing weary of military setbacks.

Barnes Wallis later turned to much heavier “earthquake” bombs like Tallboy and Grand Slam. These were used against the German U-boat pens and V-weapon facilities with devastating effect. After the War, he continued working on novel aircraft designs till his retirement in 1971. He died on October 30, 1979, with Molly by his side.