And then on July 19, out of the blue, Wallis got an urgent summons to see Lord Beaverbrook, the bright-eyed firecracker who was Minister for Aircraft Production. With “The Beaver” interested anything could happen, and probably at speed. He caught the first: train to London, cooled his heels a few minutes in an ante-room and then the big door opened and a young man said:
“Lord Beaverbrook will see you now, sir.”
Wallis jumped up, cuddling his calculations under his arm, and crossed the threshold, nervous with anticipation; and there was the little man with the wide, mobile mouth, sitting slightly hunched in his chair. It was the speed with which things happened that shook Wallis as much as the things themselves. No gracious, measured preliminaries. He was still in the middle of the floor, walking, when the little man barked:
“What’s this about a ten-ton bomb?”
Wallis told him as concisely as he could; difficult for a scientist, who always feels compelled to go into technicalities, but he kept it short and lucid and Beaverbrook was interested.
“You know how short we are of stuff,” he said. “This thing’s only a theory. We’d have to stop work on other vital things to make it and then it might be a flop.”
“It won’t be that,” Wallis said stubbornly.
“We’d still have to stop work on other things.”
“It will be worth it.”
“Take too long, wouldn’t it?” said “The Beaver.” “A ten-ton bomb and a bomber twice the size of anything else sounds like something in the distant future.”
“We can do it in stages, sir,” Wallis said. “I’ve got drawings for two-ton and six-ton bombs on the same principle. My Wellingtons can carry the two-tonner all right. The new four-engined ones can carry the six-tonner. They’ll be operating in a year.”
“Well, I’ll see my experts about it,” Beaverbrook said. “If it’s going to mean diverting too much effort I don’t like your chances.”
Little seemed to happen for a while but behind the scenes things were moving in a ponderous government way. Little snippets filtered through to Wallis, particularly from that astute ally, Arthur Tedder. Nothing much; just that So-and-so had consented to look into the idea and that So-and-so had expressed mild interest. Wallis thought the prospects were still favourable. Sir Charles Craven, managing director of Vickers, was sympathetic and felt confident enough on November I to write to Beaverbrook suggesting he give permission to go ahead on both 10-ton bomb and Victory Bomber.
Then Tedder was posted to take over the R.A.F. in the Middle East and Wallis had lost his keenest supporter in the sacred and essential precincts of Whitehall. It was soon after that Craven sent for him.
“I’m afraid I haven’t very encouraging news for you,” Craven said as kindly as he could. “Air Council seem too wary of big bombs. They still believe stick bombing is necessary.”
“But can’t they see what a really big bomb would do?” Wallis said pleadingly.
“Apparently not. They say that from experience they would rather drop four 250-pound bombs than a thousand-pounder. Much less a 22,000-pounder.”
“Could they understand my calculations, sir?”
Craven did not comment on their understanding. He said diplomatically that he doubted whether the members would have the time to go individually through all the calculations. Which was probably true. And then gently: “They say that anyone who thinks of ten-ton bombs is mad.”
Wallis went back to Weybridge in anger, but in the morning the anger had mostly gone and in its place was outraged stubbornness. He started writing a treatise on his 10-ton bomb and called it “A note on a method of attacking the Axis Powers,” the kind of obscure title so favoured by scientists; the word “note” being particularly misleading, as such things are often as long as a book.
Wallis’s was. He started by outlining his theory of crippling an enemy by destroying the sources of energy, and went on to discuss in exhaustive detail the physical qualities of the targets, shock waves, blast, penetration, bomb design, aircraft design, charge/weight ratios, aiming problems, possible effects, repair potentialities, backed up with pages of graphs and formulae and equations. It was a tour de force, explaining step by step so lucidly that a layman could follow it if he took the mathematics for granted.
The “note” took Wallis several months, and then he had it roneoed and bound and posted copies to seventy influential men in science, politics and the services.
Results were not long coming. A secret service man called on him with a copy of the “note” under his arm.
“Did you send this to Mr.–—?” he asked.
“Yes,” Wallis said. “Why?”
“I’m afraid you shouldn’t have done so, Mr. Wallis.”
“Why?”
“It’s very secret stuff. This sort of thing must be handled very carefully and only reach authorised persons. Mr.–— was very surprised when this arrived in the post. We were concerned too. I quite realise you didn’t mean to be…”
“I sent out seventy of them,” Wallis said calmly, and the Secret Service was appalled.
“Seventy!” he said. “Seventy! Who? To whom? But you shouldn’t have. This is vital and very secret ! “
“Is it? “said Wallis mildly. “When I showed it to the authorised persons they said I was mad. I’m supposed to be a crackpot and this is regarded by authorised persons as fiddle-faddle.”
The secret service man said, “Oh ! “He asked for the names of the seventy. Wallis read them out and the secret service man, who seemed a little uncertain of his ground, went back to London to investigate further.
He appeared again a couple of days later.
“Well, it’s all right,” he said, “this time. We’ve decided that as so many were sent out so openly it’s actually rather a good form of security. No one will dream it’s all so secret. But please don’t do it again.”
Wallis bowed gravely. “I hope it will not be necessary again,” he said and the incident was closed.
A few days later there was another result. A copy had reached a Group Captain Winterbotham, who had an office in the City and was used to dealing with unorthodox aspects of the war. He had found it convincing, called on Wallis, and Wallis explained more fully. Winterbotham caught some of his enthusiasm. He knew Sir Henry Tizard, who was scientific adviser to the Ministry of Aircraft Production, and drew his special attention to Wallis’s paper.
Tizard read it carefully; as a scientist he could follow the intricate calculations. He went down to see Wallis at Wey-bridge and was impressed.
“I’d better form a committee to study this more fully,” he said. “It would have to have pretty solid backing from expert opinion. You’ll understand, I know. It would divert effort from other important things if we were to go ahead with it and we’ve got to be reasonably sure it would be worth while.”
“Of course,” Wallis said. He felt like singing.
Not long after, Wallis met the committee. At the head was Dr. Pye, Director of Scientific Research at the Ministry of Supply, and the others were scientists too. Wallis explained his ideas and described the probable effect on Germany’s war industries if the dams were breached. There was only one really worthwhile time of the year to breach them, and that was in May, when the storage lakes were full after the winter thaw and spring rains, and before the sluice gates were opened to water the country and canals for summer. Then you would get the greatest floods, the most serious loss of water and power. Dr. Pye said the committee would be a few days considering.
A week later Wallis faced the committee to hear theirfind-ings. His worst fears were soon over; the report was fa vour-able, but, as they read on, a little disappointingly so. They thought that the dams showed possibilities and the upshot was another committee. This one focused the aim more definitely; it was to be called “The Air Attack on Dams Committee.”
The members were again scientists and engineers and in a mood to be interested in something new because even German bomb
s, though they were more efficient than R.A.F. bombs and killed thousands of civilians, had demonstrated the limitations of small bombs.
“With this big bomb,” Wallis earnestly impressed on them, “you don’t have to get a direct hit. I think a ten-ton bomb dropped fifty feet away stands a good chance of knocking a hole in a dam like the Moehne. A near miss like that ought to be simple enough to organise.”
One of the members, Dr. Glanville, of the Road Research Laboratories at Harmondsworth, suggested building a model dam and testing the theories with scaled-down charges of explosive. Wallis accepted delightedly.
Over the next few months, whenever he could spare time from his arduous work at Vickers, Wallis helped Glanville design and painstakingly build a model dam one-fiftieth the size of the Moehne with tiny cubes of concrete, scale models of the huge masonry blocks in the real dam. The model was about 30 feet long, 33 inches high and up to 2 feet thick, a low wall arched between earthern banks, secluded from prying outside eyes in a walled garden.
They flooded the ground at one side to simulate the lake, and Wallis exploded a few ounces of gelignite under the surface 4 feet from the model to give the effect of a 10-tonner going off 200 feet away. There was a commotion on the water and a couple of patches of concrete flaked and chipped.
“Not so good there,” Wallis said. “Let’s try it closer.”
He exploded more gelignite 3 feet from the dam, and there was a little more damage. He set off another charge 2 feet away and still found only minor chipping.
At a distance of 12 inches (representing a 10-tonner 50 feet from the dam) the gelignite caused a couple of cracks in the outer structure; but they were small cracks, not enough to harm the dam significantly. They tried several more charges but the cumulative effect was not encouraging.
Months had passed since the first hopeful meeting of the committee, and Wallis could see that their early co-operation was freezing. Glanville built another model, and Wallis tried bigger charges to see what would smash the models at a distance. One day a few extra ounces of gelignite a foot away sent a mushroom of water spraying over the wall round the garden and as the spume cleared they saw the water of the little lake gushing through the burst dam. Slabs of concrete had cracked and spilled out and there was the breach that Wallis had been wanting. He calculated the scaled-up charge which, dropped 50 feet away, would smash such a hole in the Moehne. The answer was something like 30,000 Ib. of the new explosive RDX, and the gentle scientist did not need pencil and paper to estimate the significance.
Thirty thousand pounds was nearly 14 tons. That was the explosive alone. Add the weight of the thick case of special steel—another 40,000 odd Ib. It meant a bomb weighing 70,000 Ib.—over 30 tons, and the Victory Bomber, still only on paper and straining the limits of feasible aircraft construction, would carry only a 10-tonner.
The next meeting of the Air Attack on Dams Committee was in a fortnight and it required little thought to foresee it would be the last meeting.
Wallis would not give up.
Supposing, he thought, a bomb could be exploded under water against the dam wall. The shock wave punch would be much greater. So the explosive needed would be smaller. So would the bomb casing.
But how to get a big bomb in the exact spot—deep enough for the shock punch and pressed against the wall to make the most of it? Or, as it might require more than one bomb, how could you get them all in the exact spot? A torpedo? But the dams had heavy torpedo netting in front of them, and so torpedoes were out. You could drop a bomb from very low level for accuracy, but bombs don’t simply “drop “. Just after release they carry a lot of forward speed, giving them almost a horizontal trajectory for a while. If you dropped a bomb— even a whopper—from very low to get the accuracy it would simply skid off the water ; so that was no good. If you dropped it high enough to enter the water cleanly, you only had about one chance in a thousand of putting it right in the exact spot.
Wallis probed at this problem for days and every time he probed he came slap up against the same old problem—the only way would be to drop something from very, very low and somehow make it stay where it was supposed to. But that seemed to be impossible. He remembered his last holiday with the youngsters just before the war began when they had been skipping stones across the smooth water of a little pon,d. How on earth, he thought, could one toss a stone low like that and stop it skipping. Drop any shape of bomb very low at a couple of hundred miles an hour and heaven knows where it would skip to. When dams are full there is practically no space between the level of the water and the top of the dam wall and in his wry imagination he visualised a series of grotesque bombs hurdling over the dam wall and flying harmlessly downstream. What a pity, he thought idly, that you couldn’t make a torpedo do a bit of hurdling—over an anti-torpedo net for instance.
Hullo! That was an idea! If a bomb could hurdle a dam wall it could also hurdle an anti-torpedo net. Such nets were a good hundred yards away from dam walls to keep any explosions at arm’s length. A bomb didn’t have to keep skipping for ever. May be it could be so judged to skip the torpedo net and not skip the dam wall. Hang it all, why not? He felt sudden excitement surging inside him. There would probably be three or four feet of dam wall above the water. Supposing the skipping of the bomb were timed (if it could be done) so that it was slithering to a stop on the water as it reached the wall. Why then, the wall would stop it dead and it would simply sink into the water, by the wall, as deep as you like. You could have the fuse fixed with a hydrostatic trigger so that the bomb would go off when the water pressure reached the right amount. Set in for fifty feet down or a hundred and fifty feet down. Please yourself. Hang it, the more he thought about it the more he liked the idea, even if it did sound a bit odd.
Wallis went home, dragged a tub into the garden of his house at Effingham and filled it right to the top with water. Then he rigged up a catapult a few feet away just a few inches above the level of the water. A few feet on the other side of the tub he stretched a string between a couple of sticks so that the string was also just above the level of the water. Then he borrowed a marble from his young daughter, Elizabeth, and shot it from the catapult at the water. It skipped off and cleared the string by several inches. Elizabeth and the other children looked on, wondering what he was up to. Elizabeth brought the marble back and Wallis fired it again, this time with a little less tension on the rubber of the catapult. The marble zipped off the water and only just cleared the string. “Ah,” thought Wallis, “that’s it.”
He and the youngsters spent the whole morning playing with the marbles and the water and the catapult and the string, trying different combinations of power and height while Wallis was finding out how much he could control the skip. To his deep joy he found out that with a regular shape and weight like a marble on smooth water he could control it quite well. At least well enough for it to be distinctly encouraging. But could he control several skips, which might be necessary? Aha, that remained to be seen. They went into lunch eventually, all thoroughly splashed. Wallis was very cheerful, and also, the children thought, very mysterious about it all.
Always sensitive to ridicule, Wallis told no one the details, not even his friend Mutt Summers, chief test pilot for Vickers and the man who had tested his old warhorse, the Wellington. Captain Summers was a hefty extrovert and not the type to take a freak idea seriously.
The day of the meeting of the Air Attack on Dams Committee Wallis went early to London, buttonholed the chairman, Dr. Pye, and privately explained his new theory, so earnestly that Pye did not laugh though he looked a little sideways.
“I’d rather you didn’t tell the others yet,” Wallis said. “They might think it a bit far-fetched.”
“Yes,” said Dr. Pye. “I see that. What do you want me to do?”
“Give me time to find out how much RDX will blow a hole in the Moehne Dam if it’s pressed up against the wall.”
Pye talked eloquently to the committee without giving Wallis’s s
ecret away. The members were reluctant when they heard the results of the last model’s test and Wallis was like a cat on hot bricks till they consented to one more experiment.
Glanville built him a new model dam, and Wallis started with small charges, sinking them in the water and exploding them when they were lying against the slabs of concrete. The effect was shattering—literally. He smashed wall after wall seeking the smallest charge needed, and soon he knew that in a contact explosion tamped by water a tiny plug of a few ounces of gelignite blasted a satisfying hole through a concrete wall 6 inches thick. From that he calculated he would need only 6,000 Ib. of RDX to breach the Moehne Dam. With his new idea he could cut the case weight down to a little over 3,000 Ib., making the complete bomb about 9,500 Ib. Less than 5 tons. The new four-engined Lancasters would carry that to the Ruhr without trouble.
CHAPTER III THE GREEN LIGHT
ARMED with sums and theories, Wallis faced the task of convincing officials in their brick and stone lairs along Whitehall and other influential thoroughfares that he could put his bomb in the exact spot. He called on Professor Patrick Blackett, director of an “operational research” branch, and Blackett, a spare, rather intense man, listened to his ideas, carefully examined the calculations, riffled them back into a neat pile and said quietly:
“We’ve been looking for this for two years.”
Wallis was electrified.
“I’d like you to leave these with me for a while,” Blackett said. “There are one or two people I know who would be interested.”
Blackett moved fast. As soon as Wallis had left he went to see Sir Henry Tizard and told him what he had heard. Tizard also moved with unorthodox haste, driving down to Weybridge next morning, where Wallis eagerly explained it all again.
“It seems,” Tizard said when he had finished, “that the main thing to establish is whether this freak of yours will really work, and if so how we go about putting it into practice.”
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