Decoy

by Dudley Pope

  Ned could imagine Yon, happy now his beloved engines were running. By now the noise from those eighteen cylinders would be deafening and Yon and the engine room artificers would be anxiously watching the various dials and gauges which revealed their secrets in the German language and metric measures. The largest dials, as big as frying pans, were the crankshaft tachometers, one high on each side of the corridor running between the two diesels. Then on each side were nine rectangular gauges mounted in a vertical bank, like a stack of large glass-fronted letter boxes, except that the dials behind the glass fronts recorded cylinder temperatures. Nine on one side, nine more on the other, each in effect an eye which revealed what was going on in the cylinders.

  Three similar-looking gauges to one side of the vertical bank told the temperature in the exhaust manifolds. Another pair of gauges, as bulky as small searchlights and arranged on each side, were the engine room telegraphs: indicators which made a penetrating noise until an outside pointer was lined up with the inner one, acknowledging the order from the control room.

  Ned had marvelled at the clever way the two huge diesels were squeezed in, each separated by the narrow corridor which ran from the control room, through a circular hatch in the bulkhead which could be shut and screwed tight to make it watertight, then into the electric room, with the two big motors which drove the propellers when the boat was submerged. Right now, with the boat surfaced and the diesels running, those motors had been turned into generators and were charging the batteries.

  To a layman, the control section for each diesel was a bewildering mass of control wheels, from a few inches to a couple of feet in diameter, with so many different-sized pipes that no plumber’s feverish nightmare could equal it. Yet standing in one position an ERA could see the heat of every one of the nine cylinders for which he was responsible, the temperature of the exhaust gases, the crankshaft revolutions, the speed ordered by the captain for his particular engine (and propeller shaft), and a dozen other things ranging from the temperature and flow of the cooling water to the flow of fuel. Just beside him, fans encased in bulky trunking supplied the vast amount of air the diesels needed.

  The next section aft was, by comparison, as clean and antiseptic as a medical laboratory: there each of the two big electric motors had its own control panel – ammeters and voltmeters as big as soup plates, telegraphs like those at the diesel positions, tachometers showing the shaft speeds, the rate of discharge of the batteries when the motors were driving the boat, the rate of charge when they were being turned by the diesels and making electricity.

  Up on the tiny bridge, Ned felt like a man standing on the chimney of an enormous house: below him, unseen dozens of people slept, ate, talked, as remote inside the hull of the boat as they would be below a tiled roof.

  Below and slightly aft on the waterline, the diesels’ exhausts alternately thundered and mumbled as waves surged over the vents, reminding Ned of an asthmatic lion lying in the corner of a cage, now roaring, now wheezing. He thought how every turn of the two propeller shafts spun the generators and sent amperes surging back into the batteries: he could picture the needles on the voltmeter dials, as big as dinner plates, gradually moving back up again. Yon will have to check the specific gravity of the electrolyte in the batteries – or, rather, someone will lift up floor plates and climb down on to the little trolley that runs along a beam past the batteries, so he can unscrew the caps and test each cell with a hydrometer, adding distilled water as necessary.

  What batteries they must be: two large banks of them, each the size of a large bin, and together providing enough power to drive this boat of 770 tons displacement, seventy-five metres long and six metres in diameter, at nine knots for an hour’s spurt, but for three days if she ambled along at one or two knots. And she could do that at a depth of 100 metres…say fifty-four fathoms. And the Croupier had once received what they now knew was a BP intercept of a U-boat’s signal to B der U reporting that she had survived after being forced down to 245 metres – say 735 feet, over 120 fathoms – to avoid a heavy depth-charge attack. Yes, that was U-230, and at that depth, Jemmy had explained, the explosive effect of a depth-charge is reduced to a third, because of the immense pressure of water.

  Still, the strain on the submariner’s nerves, diving to more than twice the depth for which the boat was designed, must be considerable, knowing that at any moment the hull could be squeezed like a crushed eggshell. Submariner’s twitch – doctors at the naval hospital at Haslar ought to publish a paper on it. Except, Ned remembered bitterly, the Navy could not admit it existed, any more than the RAF could admit that air crews were human beings who had a breaking point: instead the Air Ministry invented ‘LMF’, ‘lacking in moral fibre’, and that was the label they pinned on imaginative men who finally cracked up after a couple of dozen bombing raids which may well have killed half the men in the mess. The men who ought to receive those labels (the equivalent of the old ‘Unclean’ from the time of the plague) were those who lacked the moral fibre to face up to the fact that brave men could be driven only so far, and of course the psychiatrists also lacked the moral fibre to stand up to authority…

  ‘Commander Yorke…will commander Yorke please go to the wireless room!’

  Chapter Seventeen

  The sudden call coming up the conning tower hatch startled Ned, who at that moment was comparing going at full speed in a North Atlantic winter while standing on the open bridge of a destroyer with doing the same thing in a U-boat. Though admittedly the U-boat was a vile experience, like being lashed to the high water mark of one of the rocks at the foot of Beachy Head, a submarine at least gave you a chance to cry quits and submerge.

  ‘They haven’t got that bloody transmitter to work, I suppose?’ Jemmy said as Ned started down the hatch.

  ‘Not a hope. They’ve probably intercepted an AFO ordering all left-handed armourers to wear clean socks on Wednesday.’

  Admiralty Fleet Orders sounded impressive to soldiers and airmen, but to the Navy they rarely rose in interest or importance, as a destroyer captain had once commented to Ned, to the height of Wrens’ knickers.

  He felt his way carefully down into the vertical cylinder of the conning tower, with its dimmed lights. The helmsman was a shadowy figure, an Essex man called Coles.

  ‘How does she handle?’

  ‘Very odd to start with, sir. She’s so long and thin she is hard to turn once she gets off course, but at the same time that helps keep her on the straight and narrow.’

  Looking down into the control room through the bottomless dustbin affair of the hatch, Ned decided to practise a rapid drop, of the kind that would be expected of him if he was on the bridge when the time came for an emergency dive.

  He held the aluminium sides of the ladder, went down one rung and then kicked back with the other foot. He landed on his knees with a crash and set the floor plates rattling and the startled men at the hydroplanes swung round in their seats while Yon hurried over to help him up.

  ‘Sorry, sir: the call from the Croupier wasn’t that urgent.’

  ‘My fault,’ Ned said. ‘I was playing silly buggers, just seeing how fast I could get down the ladder,’

  ‘Without breaking a leg,’ Yon added.

  ‘Yes, I shall regard that as par for the course.’

  He found the Croupier and Hazell radiating excitement. Hazell, earphones clamped over his head, was writing rapidly on a signal form, a number of which the Croupier was already holding and inspecting like a bridge player who had just been dealt a perfect no-trump hand.

  The Croupier turned to Ned and explained above the dull roar of the diesels: ‘Old Doughnuts is just sending off his night orders and questions. We’ve copied signals to five U-boats, and one for us is just coming over now. I thought you’d like to be here when I put it through the cash register.’

  Ned shook his head with sheer frustration. BP, the A
dmiralty and ASIU now had no idea where the U-boats were, thanks to the switch from Hydra to Triton and the Mark III Enigma, but here on board the prize U-boat an ASIU group had an actual machine, the key to the cipher, a pile of signals…and a pair of burnt-out valves.

  Hazell’s right hand kept jotting as his ear heard the Morse dots and dashes and his brain translated them into letters. From time to time his left hand moved up to the front panel of the receiver to make a slight adjustment to the tuning.

  He tore a page from the pad, handed it to the Croupier and continued writing on the new sheet.

  ‘That’s all for us,’ the Croupier said. ‘Let’s get the book and put it through the cash register. You have the keys…’

  Ned went through to the Captain’s cabin opposite, pulled out the padded panel, unlocked the safe and took out the manual. As he relocked the door and pocketed the keys, he found he was holding the Triton manual as though it was an early Shakespeare, and was startled to find when he returned to the wireless cabin that the Croupier was cocking his Walther automatic.

  ‘Just in case the prisoners have worked out why we’re here and try to rush us since we’re surfaced,’ he explained, reaching for the manual. ‘Just think, Ned: this flatulent typewriter –’ he tapped the Enigma machine which was, indeed, like a plump portable – ‘and this manual are the key to the Battle of the Atlantic, and the Battle of the Atlantic is the key to the war, and freedom for millions.’

  Ned smiled patiently and said: ‘Yes, quite. Hurrah and whizzo. I’ve been wearing my Freedom braces and working on that basis ever since Watts and I went to see the PM.’

  ‘Oh, you’re a miserable sod,’ the Croupier grumbled. ‘Get excited just for once! This is Robin Hood and Christmas and V for Victory and Cowboys and Indians and bugger Cromwell all rolled into one!’

  ‘Yes – but just bear in mind, Red Riding Hood, that you have to keep an eye open for the Big Bad Wolf!’

  The Croupier opened the manual. ‘Right, I’ll translate and read it out, and you juggle with the rotors. Now, let’s find the right day.’ He flipped through the pages. ‘Here we are. Now, these settings for today would have been put on the Enigma at just past midnight.’

  Ned opened the lid of the machine, revealing the typewriter keyboard in front, then the three rows of glass-topped letters duplicating the keyboard, and then four rotors already fitted, with four spare rotors in a rack to the right.

  ‘The four-rotor Mark III isn’t any bulkier than the models the Wehrmacht and Luftwaffe use,’ he commented. ‘Perhaps an inch or so wider.’

  The Croupier nodded, and with his right index finger marking a place in the manual said: ‘Right, from those eight rotors – no, wait a second; take out the four they were using the last time and the four spares. Now, here’s the first one we need.’ He pointed to the Roman numeral VI. ‘Find that.’

  Ned sorted through the rotors until he found one with the number engraved on it. ‘So I put that one in position, out of the way.’ He glanced curiously at the rotor, with its twenty-six letters of the alphabet neatly engraved round it, so that it looked like a huge coin with letters replacing the milled edge.

  ‘Right,’ the Croupier said briskly, ‘now II…then VII…and finally I.’ He had been reading them out so that seven was ‘vee one one’.

  Ned clicked the rotors in position, put the remaining four spare rotors in the rack to the right, and waited for the next instruction.

  ‘Right, now we have to fix each rotor in relation to its disc, or wheel.’ He glanced up at Ned, noted his look of impatience and said: ‘Yes. I know, but let’s work slowly and avoid mistakes. So here we go. The first disc number is twelve.’

  Ned counted on his fingers the letters of the alphabet until he reached twelve. ‘L.’ The Croupier nodded in agreement and Ned turned the notched disc of the first rotor until a mark on it was against the letter L on the rim.

  ‘Three,’ the Croupier said. ‘This is like housey-housey. Letter C!’ Ned took out the second rotor, rotated the notched wheel, and replaced it.

  ‘Twenty-two…’ The Croupier started counting but Ned quickly went back four from Z. ‘V – for victory, by jingo!’ He adjusted the third disc.

  ‘Now fifteen.’

  Ned turned the fourth disc until the mark was against O on the rotor, and after replacing it read out the sequence: ‘L,C,V,O.’

  ‘Right,’ said the Croupier, ‘now we’ve set each rotor in relation to its own disc. Now we have to set the four rotors in relation to each other.’

  As Ned shut the lid of the machine he was conscious that Hazell was still writing on the signal pad, and that he had four or five pages held down under his left elbow.

  ‘Here we go,’ the Croupier said. ‘Four figures representing letters of the alphabet.’

  Ned looked down at the machine. The four small slots in the lid, side by side, revealed a single letter of the alphabet on each of the four rotors, and alongside each window a section of a notched wheel also protruded.

  ‘Ten,’ said the Croupier, adding: ‘That’s the letter J.’

  Ned pressed down on the first notched wheel and rotated it until he could read the letter on the rotor in the window.

  ‘Second is nineteen.’

  ‘S!’ said Ned, rotating the second wheel.

  The third letter proved to be P and the fourth was R.

  Ned dropped the hinged front of the box ready for the next and last settings – fitting a series of small plugs into sockets, the whole thing looking like a miniature telephone switchboard.

  ‘The Stecker, as the Teds call ’em,’ said the Croupier. ‘Only four for today – connect the F plug to the S socket, T to M, that’s it; then P to K, and S to B. Now we’re ready to see what old Doughnuts has for us.’

  Ned swung round the back of the chair, sat down in front of the machine and flipped up the on-off switch.

  The Croupier put the sheet from the signal pad in front of him and Ned slid a blank pad and pencil close by.

  ‘Right – the preamble, which isn’t in cipher,’ the Croupier said. ‘We might as well write it all down. Ready? “B der U to ULJ, time of origin 18.22, 44 letters in text, first part of one part then…”’ The Croupier’s brow wrinkled. ‘Oh yes, that three-letter bit means it’s in the Triton cipher. All the preamble setting is BJEK.’

  Ned leaned forward and turned each of the four discs until they showed, from left to right, the four letters BJEK in the windows.

  The Croupier picked up the pencil and pad. ‘Ready,’ he said, ‘the magic word is ZCAL.’

  Then, with the rotors set at BJEK, Ned slowly typed ZCAL, with the Croupier noting down the corresponding letters as they lit up on the lamp board.

  ‘There we are, WLDP. We’re nearly there, Ned!’

  Ned turned the discs until the engraved letters on the edges of the four discs showing in the windows were WLDP.

  ‘Let’s check,’ said Ned. ‘First we had the machine on the correct setting for the day.’

  ‘Correct.’

  ‘Then we set the discs to BJEK, which are the random letters chosen at Kernével.’

  ‘Correct.’

  ‘Then we typed the first four letters of the signal, ZCAL, which with the BJEK setting gives us WLDP on the lamps.’

  ‘Correct. Now you set the discs to WLDP…’

  ‘And then we’ll get the hot words from Doughnuts,’ Ned said cheerfully. ‘Right, you read out the letters from the signal, and then as I type you write down whatever letters these lamps show.’

  The Croupier read letter by letter and as Ned tapped the corresponding key the Croupier wrote down the letter lit up by the lamp.

  Finally, with the last letter typed and its encoded equivalent lighting up, the Croupier groaned.

  ‘Brief and not very exciting. Doughnut
s is telling us: “Report position and fuel and torpedo expenditure.”’

  ‘Sounds as though we should have made a routine signal last night: and this is the routine reminder.’ Ned commented. He swung round on the seat and saw that Hazell was still busy taking down more signals.

  ‘Let’s knock out some more of those and see what he’s telling other boats.’

  The Croupier took the pile of signals forms from under Hazell’s elbow and the two went back to work with the Enigma machine. As the Croupier copied down the last letter coming up on the lampboard, he grunted.

  ‘That’s more like it. Doughnuts to UL. “Proceed full speed grid square QA 94 convoy reported course 095 speed six knots.”’

  Ned pictured the gridded chart. ‘That’s several hundred miles east of us.’

  ‘Right, so let’s do the next.’

  As the Croupier glanced at it, he commented: ‘Ah, this is a boat report to Doughnuts.’

  The signal was brief but explicit as the Croupier translated and read it out, explaining that he was inserting punctuation: ‘“Sunk two ships ten thousand tons, depth-charged fifteen hours, after hydroplanes damaged. Contact with convoy lost. Returning to base.” That’s UBT.’

  He took another signal ‘Another to Doughnuts.’

  They began to work at the Enigma again as Hazell pulled up one earphone with a sigh. ‘Phew, must have been children’s hour for the U-boats! They can keep quiet for ten minutes now, so I can give my hand a rest!’

  Again the Croupier grinned. ‘Another U-boat reporting to Doughnuts from grid square LA 19 –’

  ‘That’s near us,’ Ned said.

  ‘…Well, he’s damaged. He says: “Attacked convoy grid square LA 19 zigzagging seven knots through mean course 085 heavily depth-charged and lost contact.”’

  They put five more signals through the machine and found them to be either routine sighting reports, or Kernével requesting meteorological reports and ordering several U-boats to report their positions.