A four-month bombing campaign against the cities of the Ruhr, aiming to pulverise and paralyse the heavy industries based there and so to disrupt Germany’s war production, had begun on 5 February 1943 with the bombing of Essen. But arguably, the most crucial targets were the string of dams in the hills flanking the Ruhr. They not only generated some of the power the heavy industries required, but also supplied drinking water to the population, pure water for steel-making and other industrial processes, and the water that fed the canal system on which the Ruhr depended, both to move raw materials to the factories and to carry finished products – aircraft parts, tanks, guns and munitions – away from them.
However, attempts by Main Force – as the squadrons carrying out mass bombing raids in Bomber Command were known – to attack small targets with the required accuracy had so far proved ineffective. Where the requirement was for saturation bombing over a broad area, Main Force could be brutally effective, as the thousand-bomber raid that devastated Cologne at the end of May 1942 had already demonstrated. But regular success in bombing individual targets – particularly if they were as difficult to access and as ferociously defended as the dams – had proved elusive.
Attacks by torpedo bombers like the Bristol Beaufort and the Fairey Swordfish were foiled by a lack of suitable weapons and by heavy steel anti-torpedo nets strung across the waters of the dams to protect them. A more radical solution was needed and the British engineering genius Barnes Wallis supplied it: the Upkeep ‘bouncing bomb’, a cylindrical weapon like a heavyweight depth charge, imparted with backspin to rotate it at 500 revs a minute. If dropped at the right height and distance from the dam, the bomb would skim like a pebble thrown across the surface of the water, bounce over the top of the torpedo nets and strike the dam wall. The backspin would then hold it against the face of the dam as it sank below the water before detonating to blow, it was hoped, the dam apart.
Having demonstrated the theoretical effectiveness of the bomb, all that was needed was a squadron of bomber crews capable of delivering it with sufficient accuracy. Since no such squadron existed, it became necessary to create one – 617 Squadron – and at the end of March 1943 recruitment of suitably skilled and experienced crews began under the leadership of Wing Commander Guy Penrose Gibson. He was a man with a glowing reputation as a fearless pilot, willing to take off in even the most marginal weather and attack the most heavily defended targets, whether capital ships or military or economic targets. The head of Bomber Command, Air Marshal Arthur ‘Bomber’ Harris, later described Gibson as ‘the most full-out fighting pilot’ under his command and ‘as great a warrior as this island ever bred’.
Gibson had flown two full tours on bombers and one on night-fighters, completing the astonishing total of 172 sorties even before joining the new 617 Squadron. As a Squadron Leader and then a Wing Commander, he was as ruthless in screening his crews as he was aggressive in facing the enemy. That ruthlessness and an often abrasive and patrician manner, particularly with NCOs and ‘other ranks’, made him enemies – some of his ground crews nicknamed him ‘The Boy Emperor’ – but none could deny his courage or skill as a pilot, which were reflected by the Distinguished Flying Cross and Bar and Distinguished Service Order and Bar he had already been awarded prior to joining 617 Squadron.
Gibson was given a free hand in choosing men – all volunteers – from among crews who had already completed, or nearly completed, two tours of operations. The screening process continued even after they were chosen; Gibson posted two crews away from the squadron after deciding they were not up to the task and a third crew chose to leave after their navigator was also deemed unsatisfactory by Gibson. Intensive training of the remainder lasted for several weeks. In April 1943 alone, his crews completed over 1,000 flying hours, and at the end of that time Gibson reported that they could fly from pinpoint to pinpoint at low level in total darkness, fly over water at an altitude as low as 60 feet and carry out precision bombing with remarkable accuracy. They practised the raid itself using reservoirs in the Peak District and Rutland as substitutes for the Ruhr dams, and after a full-scale dress rehearsal on 14 May 1943, simulating the routes, topography and targets of the actual raid, Gibson pronounced it ‘completely successful’. The Dambusters – though no one yet called them that – were ready to take flight.
They had been training for six weeks in the utmost secrecy for a low-level bombing mission, but none of them knew the actual targets until the final briefing on the day the raid was to be launched. When they were told, every man in the room felt a stab of fear, ‘and if they said any different,’ says air gunner Fred Sutherland, ‘they’d be lying, because it looked like a real suicide run.’1
They were to target three dams – the Möhne, Eder and Sorpe – and their destruction would cause catastrophic flooding in the Ruhr valley and massive disruption to power generation, water supply, canal transport, agriculture, coal-mining, steel-making and arms manufacturing. If the raid successful.
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On the nights she was not on duty, telephone operator Gwyn Johnson would often lie in bed, waiting in vain for sleep to come. She could sometimes hear the low, grumbling engine note of the bombers of 617 Squadron on their nearby base breaking the stillness of the night as, one by one, each pilot fired up his Lancaster’s four Rolls-Royce Merlin engines and began to taxi from the dispersal areas to the end of the runway. She could picture them waiting until a green light flashed from the runway controller’s caravan, when each pilot in turn pushed the throttles to the stops and his heavy-laden bomber began rumbling slowly down the runway. The noise swelled as one by one they lumbered into the air before finally disappearing into the night, the roar of the engines fading again to a sound like the distant rumble of thunder from a summer storm.
Not knowing whether her husband, Bomb Aimer Sergeant George ‘Johnny’ Johnson, was flying with them on any particular night, she often fell into an uneasy, fitful sleep, and a few hours later, as dawn approached, would wake again as she heard the aircraft return, no longer in a compact formation, but spread across the sky.
Hours later – if he had time – she might meet her husband for a snatched cup of tea in a cafe. He’d tell her if he’d been flying the night before and, though he gave her only the sketchiest details of the mission he’d flown, the look on his face was enough to tell her whether his comrades had returned safely or, more often than not, when one or more aircraft would have failed to return.
Yet, says Johnson, recalling those events seventy years later, ‘Gwyn had the same confidence as me that I would always come back. We both had an absolute belief we would survive.’2 Johnson, a country boy from a small Lincolnshire village with a habit of talking out of the side of his mouth as if all his conversation was ‘hush-hush’ and on a ‘need to know’ basis, was the bomb-aimer in American pilot Joe McCarthy’s crew.
Johnson and the rest of Joe McCarthy’s crew had all finished their thirty-op tour of duty with their previous squadron, 97, two months before the Dams raid, when they took part in a mass raid on the docks at St-Nazaire. ‘I could have called it a day after my thirty ops,’ Johnson says, ‘but I wanted to go on.’ After completing a tour, it was standard practice to be given a week’s leave before returning to duty, and Johnson and his fiancée, Gwyn, had arranged to get married on 3 April 1943, during his leave. They’d met when he was at the aircrew receiving centre at Babbacombe in 1941. He was walking down the street with his mate when they saw two young ladies walking towards them, and Johnson recalls coming up with ‘the corniest chat-up line. I said, “Are you going our way?” to which one of them replied, “That depends on which your way is!” That was Gwyn, that was the start and I never looked back!’
However, the week before the wedding, McCarthy, now the proud holder of a DFC, called the crew together and told them that Wing Commander Guy Gibson had asked him to join a special squadron being formed for a single operation. His crew at once volunteered to go with him for that one trip. The first thing