The Dam Busters

  At Teddington, he said, was a huge ship-testing tank which would be ideal for experiments. He also thought there should be more tests to check how much explosive would theoretically punch a hole in a dam.

  “I think I know just the thing,” said Wallis, whose “damology” researches had been fanatical. “There’s a small disused dam in Radnorshire; no earthly use any more as a dam and won’t ever be. We could try and knock it down.”

  “Who owns it?” Tizard asked.

  “Birmingham Corporation.” Wallis knew all the answers.

  “We’ll try them,” Tizard said, and Birmingham Corporation, with a little prodding, said yes.

  It was a nice little dam, about 150 feet long and quite thick, curving gracefully across the mouth of a reach of Rhayader Lake, high in the Welsh hills west of Leominster. The corporation had built a bigger dam across the mouth of the lake to feed a little river that tumbled out of the hills.

  Wallis estimated that the old dam would have a fifth of the resistance of the Moehne, an ideal test model. He calculated the smallest charge that should knock it down and set off with a packet of RDX and some explosives engineers. Wrapped against the raw mountain wind, he wasted little time, measured out the charge, tamped it in a sealed casing and lowered it deep into the water against the dam wall. Behind the rocks, his mouth dry with anxiety, he pressed the plunger and the lulls echoed with sound. Water spurted a hundred feet high, the lake whipped into fury, and as the water plunged back into the void, the concrete crumbled and a hissing flood burst into the main lake. Wallis, pink with glee, saw there was a ragged hole in the dam 15 feet across and about 12 feet deep.

  For the next five months he experimented whenever he could in the tank at Teddington, an enormous thing well over a hundred feet long. He wanted to find out exactly how to control a skipping missile, so that after a given number of bounces over a given distance he could make it reach a certain given point at a certain minimum speed and height. At this ultimate spot the missile would have to be either slithering across the water or only just a fraction above it. He had to find out the best shape to use and the best combination of weight of missile, and height, speed and power of release. And what a headache it was, too. He had a spring-loaded catapult so that he could measure the force behind it, and began to accumulate an extraordinary number of combinations of heights, shapes, weights, speeds and distances. Hundreds and hundreds of times he shot his little missiles across the surface of the water and they skipped and skipped and skipped in little splashes, some of them foundering in mid-stream, some of them foundering three-quarters of the way along, some of them cracking against the end of the tank nearly fifty yards away at this height or that height, and one or two even bouncing over the end. And all this time Wallis was also trying to do his usual work at Vickers.

  He filled notebook after notebook with his records and calculations and slowly, as he pored over them at nights assessing the results, certain conclusions began to emerge from all the figures and facts. For one thing some sort of regular shaped missile gave the most consistent results. Something, for instance, like a round ball, such as a golf ball, because every time it skipped and came down and hit the water again it was the same shaped surface that hit the water. That was the only thing that enabled one to predict a bounce. Any irregular shape would only give irregular bounces. He took to concentrating on firing golf balls and bit by bit found he could so adjust the height and strength of his catapult that he could make a ball slither neatly up to the far wall of the tank. There are ways of calculating from scale experiments how a full-sized object will perform. Or that is, how a full-sized object should perform if everything goes according to plan and nothing has been overlooked. By the middle of 1942 Wallis was satisfied he knew enough to make a 5-ton bomb skip under control for half a mile ! It would look something like a big round ball of steel and he didn’t quite know whether to call it a mine or a bomb.

  Tizard was pleased, but Tizard was an adviser, not all-powerful; the task was to get executive officials keen. Wallis saw several officials, received tea and courtesy, even compliments, but not enough action to please him. Two high executives in particular who could have started things moving seemed irritatingly cautious.

  Then one of the several government operational research committees gave Wallis permission to build six half-size prototypes of his new bomb, purely for experiment, and told him he could convert a Wellington to drop them.

  In a few weeks the casings were finished, big steel balls about four feet across. Wallis filled them with a harmless substitute the same weight as RDX, and at 3 p.m. on December 4, 1942, the converted Wellington took off from Weybridge with the first bomb on board and Mutt Summers in the pilot’s seat, Wallis crouched in the nose as bomb-aimer, to test-drop off Chesil Beach on the south coast. They were not going to worry too much this time about precise speed and height. About fifty feet up and about 200 m.p.h. and, for the time being, never mind exactly how far the bomb went. It should, however, bounce cleanly about half-a-mile. Something near enough to that would do for the first test. The first thing was to see whether a few tons of steel ball would bounce according to theory.

  Off Chesil Beach Summers dived low over the water, Wallis pressed the button and watched the big black bomb rattle clear of its stowage. It took so long it seemed like slow-motion, and then it hit and vanished in a sheet of hissing white spray. Staring tensely down out of the bomb-aimer’s compartment Wallis watched with painful anxiety for it to appear. Just for a moment nothing seemed to happen and then out of the spray lurched the black ball looking somehow misshapen. It fell back into the water quite quickly, lurched drunkenly up again, hit once more, skipped another short distance and then slithered a few yards and vanished into the green depths. It didn’t seem to have travelled more than about two hundred yards and Wallis looked down, puzzled, not quite knowing what to think. It had worked but not the way it was supposed to. Something was wrong. Summers turned the aeroplane back towards Weybridge and Wallis, on the way back, trying to imagine what could have gone wrong, remembered the misshapen look about the bomb. He decided that the casing had not been strong enough. It must have crushed a little under the impact, making the bounces unpredictable and sluggish. When they landed he ordered the cases of the remaining bombs to be strengthened.

  On December 12 he and Summers took off with a strengthened bomb. Off Chesil Beach, Wallis watched the bomb going down, holding his breath, and feeling his mouth dry with anxiety. Again the hissing sheet of spray as it hit, and then: Oh the thrill, out of the spray the black ball came soaring a hundred yards across the water, hit with another flashing white feather of spray and soared out again, hit again, and again, the distances shortening every time until at last, after what looked like nearly hah0 a mile, it slithered to a foaming stop and sank. Summers had banked the aeroplane round and they could both look down on that glorious sight of the long necklace of white foaming scars on the water where the bomb had hit. Wallis had seldom known such a moment of glad triumph. He crawled half-way out of the nose to look up and grin at Summers above in the cockpit. The engines were making too much noise to talk but Summers grinned down at him, gave him the thumbs-up sign and an enormous wink.

  In the next three days he and Summers dropped three more bombs and they worked every time. They took a movie cameraman with them on these flights and got undeniable evidence that it worked.

  On the strength of that Winterbotham arranged an interview for Wallis with the Ministry of Supply’s scientific tribunal to assess new weapons. The tribunal watched his films and let it be known that the report would be favourable.

  With his films Wallis made a new assault on the two cautious officials. They were still non-committal, but it seemed to Wallis a little less inflexibly so.

  Slowly the weeks dragged by with no break-through, and Wallis was sinking into despair again when one day he got a call from one of the two cautious ones, giving him permission to go ahead with the preliminary design of a full-si
zed bomb. The official tempered his joy by telling him not to expect too much.

  Further work would depend on whether it would dislocate work on a new bomber.

  This was early February, 1943, and the best time to smash the dams was in May, when they were full. There was still just time. Wallis worked late over his plans and on the eighth day had them virtually finished when the bombshell dropped. One of the cautious ones ‘phoned, ordering him to stop work on the big bomb. There was to be no further action on it.

  Wallis went grimly next day to the big tank at Teddington, sank two glass air-tight tanks in the water, putting an arc-light in one and inducing a slight young woman to go into the other with a movie camera. She and the camera could just fit in. He fired a missile across the water, and as it slithered against the end of the tank and sank, the girl filmed its under-water progress. It was a beautiful film; clearly it showed the little sphere rolling down what would represent the dam wall deep under the water to the bottom of the tank.

  Next he bailed up Summers and demanded an interview with Air Marshal Sir Arthur Harris, chief of Bomber Command. Summers had known Harris for years, well enough to call him by his first name, which few people dared to do. Harris, it was freely acknowledged, could crush a seaside landlady with a look.

  Summers and Wallis drove into the wood outside High Wycombe where Harris had his headquarters, and as Wallis put his foot on the threshold of Harris’s office the booming voice hit him like a shock wave.

  “What is it you want? I’ve no time for you inventors. My boys’ lives are too precious to be wasted by your crazy notions ! “

  It was enough to strike fear into the heart of the sturdiest inventor. Wallis almost baulked, then pressed on and there was the bulky figure of Harris, grey eyes staring coldly over the half-moon glasses perched on his nose.

  “Well?” Harris was a man of few words and forceful ones.

  “I have an idea for destroying German dams,” Wallis said. “The effects on Germany would be enormous.”

  “I’ve heard about it. It’s far-fetched.”

  Wallis said he’d like to explain it, and Harris gave a grunt which Wallis took for yes and went ahead, trying not to be too involved and yet show how he had proved the theory. At the end the bomber chief had absorbed it all. Not that there was any encouraging reaction. Harris said bluntly:

  “If you think you’re going to walk in and get a squadron of Lancasters out of me you’ve made a mistake. You’re not ! “

  Waiiis started to bristle and Summers, who knew Wallis’s obstinacy and Harris’s explosive temperament, kicked Wallis’s shin under the desk. Wallis controlled himself.

  “We don’t want a squadron,” he said, “… yet. We’d like a chance to prove it in trials with one Lancaster first.”

  Harris eyed him stonily. “Maybe,” he said. “You really think you can knock a dam down with that thing.”

  “Yes,” Wallis said. “Or it may take three or four. We can put them all in the same place.”

  Summers said peaceably, “We’ll prove it’ll work, Bert.”

  “Prove it and I’ll arrange a squadron,” Harris said, and then with his old fierceness, staring at Wallis, “but I’m tired of half-baked inventors trying to run things.”

  Summers kicked Wallis once more under the desk and broke the tension by saying, “We’ve got some films here that show clearly how it works.”

  “All right. Let’s see them.” They trooped out to the Command projection room, picking up Harris’s chief lieutenant, Air Vice-Marshal Saundby, on the way. Harris curtly told the projectionist to clear out. “If it’s as good as you say,” he told Wallis, “there’s no point letting everyone know. Saundby can run the films through.”

  Saundby’s training had not concentrated much on film projection work and for a while there was a tangle of celluloid, but eventually he sorted it out, clicked the lights off and they watched in silence the antics of the bombs dropped at Chesil Beach and the tricks of the model under the water at Teddington.

  When the lights went up Harris had his poker face on. “Very interesting,” he grunted. “I’ll think it over.”

  Not long after, Wallis got a summons to a senior executive whom he knew quite well and who in the past had encouraged his bomb work.

  “Wallis,” he said, “I’ve been asked by––” (one of the two cautious ones) “to tell you to stop your nonsense about destroying dams. He tells me you’re making a nuisance of yourself at the Ministry.”

  For a moment Wallis was stunned, then recovered and answered quietly, “If you think I’m not acting in the best interests of the war effort, I think I should offer to resign from all my work and try something else.”

  For the fast and last time he saw the executive lose his temper. The man shot to his feet, smashed his fist on the desk and shouted “Mutiny!” Smashed his fist down again with another “Mutiny!” And again with a third explosive “Mutiny!” He subsided, red and quivering, and Wallis walked out of the room. He had lunch somewhere but does not remember where, and afterwards went and told the whole story to Sir Thomas Merton, one of the Supply Ministry’s inventions tribunal. Merton promised support, but Wallis came away still depressed, knowing of nothing more he could do; it seemed too late now to organise things for the coming May, and after a couple of days he was resigned to it.

  That was the day, February 26, he got a summons to the office of one of the cautious ones, and there he also found the senior executive who had shouted “Mutiny!” Proceedings opened by the cautious one saying, a little stiffly:

  “Mr. Wallis, orders have been received that your dams project is to go ahead immediately with a view to an operation at all costs no later than May.”

  CHAPTER IV A SQUADRON IS BORN

  AFTER battling for so long, Wallis, in the weeks that followed, sometimes ruefully thought he had got more action than he could stand. Life was work from dawn till midnight, planning, draughting, thinking and discussing, grabbing a sandwich with one hand while the work went on.

  He told his workers briefly what he wanted them to do, but not what the bombs were to do, or when, or where. Only he, Harris and a selected few others knew that, and apart from them a curtain of secrecy came down. Each craftsman worked on one part and knew nothing of the others. One of the first things Wallis himself had to do was to work out at exactly what speed and height the aeroplane should fly when they dropped the bombs, so that the bombs would reach the dam wall at the right height and speed.

  The full-size bomb was to be a steel sphere seven feet in girth. Roy Chadwick, chief Avro designer, started taking the bomb doors off Lancasters and doing other strange things to them so they could carry it. Explosives experts, tactical authorities, secret service men and hundreds of others had a part in it, and over Germany every day a fast Mosquito flew 25,000 feet over the dams taking photographs. Deep in the underground vaults of Bomber Command men studied the photographs through thick magnifying glasses to check the level of the rising water and the defences. If the secret leaked out they would see the extra flak and the raid would have to be called off. It was going to be suicidal enough as it was. There seemed to be at least six gun positions around the Moehne alone, and that was no matter for comfort because the bombs would have to be dropped from very low level, so low that a pilot could lean out and almost dangle his fingers in the water. They would have to fly between two towers on top of the dam, and some of the guns were in these towers.

  The Mosquitoes flew a devious way and crossed the dams as though by accident so the Germans would not be suspicious. An ugly sign appeared in the first few days: photographs showed the anti-torpedo boom in front of the Moehne was being repaired; it had been loose and untidy, and now it was being tightened. Nothing else appeared to be happening though, and after a while it was reasonable to assume that it was only a periodical check. While the work pressed on in England, it seemed that the Germans were doing nothing significant.

  At his headquarters in the wood Air Marshal
Arthur Harris (“Bert” to his friends and “Bomber” to the public) had been pondering how the attack should be made—and who should make it. On March 15 he sent for Air Vice-Marshal the Honourable Ralph Cochrane, who two days before had become Air Officer Commanding No,. 5 (Bomber) Group.

  “I’ve got a job for you, Cocky,” Harris said and told him about Wallis’s weird bomb and what he proposed to do with it. At the end he said: “I know it sounds far-fetched, but I think it has a good chance.”

  Cochrane said: “Well, sir, I’ve known Walk’s for twenty-five years. He’s a wonderful engineer and I’ve never known him not to produce what he says he will.”

  “I hope he does it again now,” Harris said. “You know how he works. I want you to organise the raid. Ask for anything you want, as long as it’s reasonable.”

  Cochrane thought for a moment.

  “It’s going to need some good aircrews,” he said. “I think I’d better screen one of my squadrons right away and start them on intensive training.”

  “I don’t want to do that,” Harris said. “I don’t want to take a single squadron out of the line if I can help it, or interfere with any of the main force. What I have in mind is a new squadron, say, of experienced people who’re just finishing a tour. Some of the keen chaps won’t mind doing another trip. Can you find enough in your group?”

  “Yes, sir.” Cochrane asked Harris if he wanted anyone in particular to command the new squadron, and Harris said:

  “Yes, Gibson.”

  Cochrane nodded in satisfaction, and ten minutes later, deep in thought, he was driving back to the old Victorian mansion outside Grantham that was 5 Group Headquarters. There could probably have been no better choice than Cochrane for planning the raid. A spare man with a lean face, his manner was crisp and decisive, perfectly reflecting his mind. The third son of a noble Scottish family, he was climbing to the top on his own ability; he had perhaps the most incisive brain in the R.A.F. His god was efficiency and he sought it uncompromisingly—almost ruthlessly according to some of his men, who were afraid of him, but his aircrews would do anything he asked, knowing that it would be meticulously planned.