Secret Weapons of World War II, page 35
The first two prototypes of Bombardon were ready by the end of December. They were brought round to Newhaven and moored there for observation, but almost immediately came an unwelcome setback. A sudden gale sprang up, and the units broke their backs. Fortunately an initial structural weakness was soon tracked down. By the end of January Admiral Tennant was able to report that the floating units were being materially strengthened, and would shortly undergo more intensive trials in Weymouth Bay.
Newhaven was deserted in favour of Weymouth because conditions in the latter area more closely approximated to those on the Normandy coast. Fifteen Bombardons were now moored in the bay — an outer row of nine and an inner row of six — and elaborate arrangements were made for recording the height, length, and period of the waves on either side of the breakwaters. For this purpose new and complicated apparatus had to be specially devised. Two 70-foot masts were erected on the sea-bed, and on these were mounted rows of watertight float switches which gave a direct recording of each individual wave. Other types of recorder were placed inside the Bombardons themselves.
The first full-scale trial of the floating breakwater took place on April 1-2. And it provided just the test for which Lochner had been hoping. An onshore gale, with a Force 7 wind gusting up to Force 8, brought heavy seas, but the Bombardons cushioned the waves so effectively that in the lee of the lines of steel bastions the crew of an American minesweeper found it possible to lower a small boat, row about, and then board the ship again without any difficulty. When the gale subsided Captain C. N. E. Curry, R.N., whom the Admiralty had placed in operational control of Bombardon, signalled that the floating harbour had successfully withstood for ten hours a stress twice as great as the breakwater had been designed to meet, repelling waves 8 feet high and 200 feet long.
While Bombardon was being prepared for this trial Admiral Tennant had to grapple with many other problems assailing this gigantic harbour enterprise. One hitch occurred when the time came to try out the raising of the Phoenix caissons. The pumping plant on which the War Office had been relying to expel the sea-water ballast from these enormous hollow structures worked too slowly, and it became necessary to make additional vent-holes in the concrete sides of the caissons.
This crisis brought an SOS to the Wheezers and Dodgers, and the job was tackled by Brinsmead, using specially shaped explosive charges. Ever since the Hedgehog days he had been experimenting at Whitchurch with the focusing of explosives, and he was able to operate quickly and successfully on the submerged Phoenixes. He knew a great deal about the effect of explosives on concrete, for he had long been concentrating on this very subject to overcome a problem which was worrying the Overlord planners.
One of the vital invasion requirements was the capture, and use at the earliest possible moment, of the major Channel ports, so that supplies could keep pace with the advancing armies. The Mulberry Harbours were essentially a short-term project; they could not compete with the potentialities of permanent ports like Cherbourg, Boulogne, and Antwerp. It was, however, well realized that the enemy would do everything in their power to deny the use of such ports to the Allies, and the approaches would almost certainly be blocked by concrete-filled wrecks.
When Brinsmead began his researches the only way of destroying such obstructions involved the use of depth-charges linked together and detonated by remote control. This system called, however, for a vast array of electric cables — always a nuisance in a tideway — and all too often much of the explosive effect was lost through failure of the charges to explode simultaneously.
Brinsmead hit on the idea of using one master charge and a series of specially shaped smaller charges, the whole network being triggered by the shock wave from the master charge through an ingenious “Wreck Dispersal Pistol” which he had invented himself. This apparatus caused the rapid disintegration of any concrete-filled obstruction. For other types of wreck he found he could use the same pistol in conjunction with groups of ordinary depth-charges, blowing enormous craters in the sea-bed, into which the obstructing blockships would capsize.
His invention solved one facet of the captured-port problem. Another was now to be tackled with great heroism in a lake near Portsmouth. For some weeks Goodeve had been attending regular meetings with Rear-Admiral George Creasy, Chief of Staff to Admiral Ramsay, and Brigadier Sir Harold Wernher. Various technical problems which might crop up on or after D-Day were constantly reviewed, and one of these was mine-clearance.
As the invasion drew near an important factor in future planning was seen to be the speed with which Cherbourg could be restored to use. It was bound to be heavily sown with delayed-action mines and booby-traps which could not be swept in the ordinary way, and these would have to be tackled individually by frogmen.
The more Goodeve thought about this, the more it worried him. There seemed to be no alternative, but he was convinced that the frogmen volunteering for this task would have little chance of surviving underwater explosions unless they could be provided with some form of protective clothing.
Eventually he put the problem to Surgeon-Commander C. L. G. Pratt, R.N.V.R., the Medical Officer in Charge of the Royal Navy’s Physiological Laboratory.
“I know we can’t protect these chaps against an explosion at very short range,” he said, “but we must find a way of reducing the risk. Do you think you can design some sort of suit which will give at least a measure of protection against underwater blast?”
“How long can you give us?” Pratt asked. “If we were going to tackle a job like that thoroughly in peace-time it might take anything up to two years.”
Goodeve thought for a moment. “You’ve only got six weeks,” he said. “In that time the suits must be tested, made, and distributed. I know it’s a tall order, but you’ll have to do your best . . .”
Later that day Pratt’s deputy, Dr S. L. Cowan, came to see Goodeve.
“I have already made a signal to C.-in-C. Portsmouth, asking for volunteers to act as guinea-pigs for you,” Goodeve told him. “Miss Stanway, in D.M.W.D., will get you everything you need in the way of equipment.”
Pratt and Cowan wasted no time. In the third week of April experiments began at Horsea Island, where there was a deep seawater lake a thousand yards long. After exhaustive tests with gauges Pratt drew up a programme of trials with human subjects. The aim was to expose each man to a series of explosions, increasing the severity of these step by step until he reached the limit of his endurance or showed signs of slight injury.
The first to subject themselves to this ordeal were Pratt and Dr Edward Case, a Cambridge bio-chemist serving as a lieutenant-commander in the R.N.V.R. Special Branch.
Dressed in ordinary frogmen’s suits, they were rowed out to the centre of the lake, and then, clambering awkwardly over the side of their small boat, they disappeared below the surface. They advanced to within 70 feet of the charge. At that distance the blast lifted them bodily in the water, and a violent stinging sensation attacked their hands, wrists, and neck. They were brought to the surface, and Cowan examined them. Then they went down again, and the tests continued, the depth of the charge being varied, while the distance between the subject and the charge was also changed before each explosion.
These preliminary trials gave them something to work on, and after comparing their notes Pratt and his helpers designed three different types of kapok jerkin. At the end of the first week in May the experiments on the bed of the lake began again.
Wearing the protective clothing, they now approached much nearer to the demolition charges, and at 40 feet they were severely buffeted. Case’s experience was typical. He felt a terrific blow on the head “it was like being hit with a cricket bat” — and for a second or two he staggered blindly about, unable to collect his senses. His chest hurt, and he had a raging pain in his ears. At this close range the stinging sensation he had experienced before became an acute pain, accompanied by an unpleasant numbness in his hands as if they were turning to ice. To make matters worse the force of the explosion displaced his face-piece, with its breathing-tube, and instantly it filled with water.
For a long time after they had been brought ashore Pratt, Case, and Lieutenant Guy Boissard, R.N.V.R., an Australian who had asked to be allowed to take part in the experiments, all suffered from splitting headaches. It was therefore decided not to shorten the distance any further, for it seemed all too likely that they might be stunned, seriously injured, or drowned; but they carried on with the tests, trying each of the different suits in turn. As many as four times in a day they went down into the icy depths of the lake. The ordeal left them battered and tired, with excruciating aches in the knees, elbows, and shoulders. In time the pain spread to smaller joints like the wrists and fingers, and was to persist for several weeks.
The trials had to go on, for they still needed more data, and there was less than a month left. By now the three naval officers realized that if they were to continue the experiments unaided the physical punishment they were absorbing might soon affect their judgment and powers of observation. So a third series of underwater tests was launched with a fresh team of volunteers headed by a young New Zealander, Sub-Lieutenant W. J. L. Smith.
Like Boissard, Smith had been serving in submarines; and he shared the Australian’s keen interest in applying scientific method to naval problems. The lake party now included two members of the Submarine Escape Training Section at H.M.S. Dolphin, Mr R. V. Rowkins, a Commissioned Boatswain, and Chief Petty Officer Watson; and a notable character in Chief Stoker George (“but me mates call me Barge!”) Evans. On the technical side valuable assistance was given by lieutenant-Commander W. O. Shelford, the Navy’s greatest diving expert.
In bitter winds and chill water the hazardous work continued. Often when they were brought to the surface of the lake the battered and semi-conscious men had great difficulty in describing their strange new experiences to the waiting scientists. But they stuck to their task, and all the information which Pratt needed was finally secured.
It is not possible to recount the precise steps which were taken to neutralize the effect of explosions underwater, but the protective suit which was produced in time for use on the sea-bed at Cherbourg was triumphantly successful. Wearing it, the “P” Parties, as the frogmen who volunteered for this dangerous mission were officially known, searched over two million square feet of the port. Much of the time they were in total darkness, and had to fight their way through deep mud, with wreckage of all descriptions littering their path, but they located and destroyed hundreds of mines.
Magnificent as their achievement was, the frogmen owed more than they knew to the self-sacrifice of that small band of scientists and sailors who had ventured into the unknown on the bed of Horsea Lake.
25
THE MIRACULOUS PORT
As each part of the prefabricated harbours was finished it had to be towed from the construction berth to make room for the next job. Finding suitable assembly areas for the vast conglomeration of harbour equipment was no easy problem, for there were 60 blockships, nearly 150 Phoenix caissons, some hundred sections of the floating breakwater, and miles of pier roadway.
To keep them safe until they were needed the Phoenix units were sunk on the bed of the Channel. This operation was not as easy as it sounded, for the concrete monsters were most particular about what they sat on. Unless the sea-bed was perfectly flat and in shallow water they were liable to crack and give endless trouble when the time came for the dispatching parties to pump them out and prepare them for their long journey.
Dungeness and Selsey were chosen as reception centres for the caissons, and as D-Day drew near they presented an amazing sight. The Phoenixes were as big as a block of flats. In Admiral Tennant’s words it looked for all the world as if “some one had picked up Chicago and put it down on the Sussex foreshore.” Additional parking areas were found for about five miles of pier roadway at Peel Bank and Marchwood, opposite Southampton, and the scene in the Solent was equally bizarre, the towering pier-heads suggesting that some vast factory had risen from the water.
The piers and pier-heads fitted together like a giant Meccano set, and their brilliantly ingenious design calls for some description. At the shore end the piers were secured to heavy ramps. As the metal roadway ran seaward over a succession of concrete barges, called Beetles, which supported it, every sixth span was telescopic to allow for the twist and sag of the pier in heavy weather.
At the seaward end the roadway was moored to “Spud” pier-heads — great floating platforms with steel legs at each corner. The inspiration for their design came from a certain type of dredger which had once ridden out a West Indies hurricane so violent that all other shipping in the area had been driven ashore to destruction.
The whole of this intricate equipment had been designed and produced under the direction of Major-General D. J. McMullen, the Director of Transportation at the War Office, and his able and forceful deputy, Brigadier Bruce White.
With such an array of ships and strange marine objects assembling off the South Coast of England it seemed inconceivable that the enemy should remain ignorant of what was afoot. The naval forces alone taking part in Operation Neptune included 8 battleships and monitors, 22 cruisers, 93 destroyers, nearly 450 escorts and minesweepers, and 360 M.L.’s, M.T.B.’s, and kindred craft; the berthing overflow extended to Mflford Haven and Harwich, the Humber, Belfast, and the Clyde.
To confuse the watchers on the enemy coast a cover plan was devised to suggest that the main landing would take place in the Pas de Calais, and the dumps of Phoenix caissons at Dungeness, easily visible from Boulogne, assisted in this deception.
In assessing the Allied intentions, however, the enemy were decisively handicapped by the inability of their air-reconnaissance units to maintain any proper survey over the South Coast of England as a whole. Days went by without a single report of any value reaching von Rundstedt’s headquarters, and the Allied naval H.Q. at Southwick Park, a Georgian country house hidden in the woods near Portsmouth, remained undetected from the air. There the only signs of enemy activity were the flying bombs, which passed regularly overhead towards Southampton.
Throughout this overture to Overlord the activities of the Wheezers and Dodgers were manifold. For months past Dove and others had been developing a variety of devices to confuse the enemy’s radar from the moment the invasion fleet sailed. There were rockets and shells which emitted coils of aluminium wire to baffle the range-finding of the German coastal batteries. To draw the enemy fire away from major targets another group of objects was produced simulating forces which did not, in fact, exist at all. Different types of reflector again made quite small craft look like battleships on the radar screen, while cruisers appeared no bigger than fishing vessels.
D.M.W.D. designed special radar marking buoys to keep the Allied bombarding ships dead on course during their night approach to the French coast. To the untrained observer these must have looked simple enough to make — just a large flag flying from a mast — but their effective operation depended on many highly technical factors, and the state of the sea, the height of the reflector above the surface, and the direction of the wind relative to the German radar sets all had to be taken into account.
Donald Currie was kept busy with the camouflage of Bombardon and Pluto and the concealment of small craft hiding up in rivers and creeks as they waited for D-Day. At Birnbeck a team headed by Coulson and Bruce was putting the finishing touches to Helter Skelter.
At the last minute the Army had asked for some means of speeding up the transfer of men and their equipment from troopships to the decks of the landing-craft. Scrambling nets, they had decided, were far from satisfactory.
So D.M.W.D. designed a tube from which stretched a long, rubberized canvas chute. The far end of this could be held quite easily by two men standing on the deck of a landing-craft; all that the soldier needed to do was to clamber in, feet first, and hurtle to the bottom.
They tried out the Helter Skelter at a factory in South London, and after several apprehensive workmen had been dispatched to earth from the fourth floor of the building without injuring themselves the device was taken to Birnbeck for more searching tests. There they soon discovered that modifications were necessary, for when it was used by some soldiers with full kit one man tore a strip clean down the canvas tunnel with the foresight of his rifle; the rest of his platoon, following close behind, all fell straight into the sea!
Bruce removed this hazard by inserting a bonded canvas lining inside the main chute. This embodied a safety-device to give prompt warning of any undue wear, and they now felt sufficiently confident to invite a detachment of American troops, quartered near by, to give Helter Skelter a thorough trial.
Fifty stalwart members of the United States Army paraded at the end of the pier, and to the N.C.O. in charge of them Bruce explained the object of the exercise. The men were to enter the tube in quick succession and dive forty feet into a small boat moored below.
Walking to the edge of the pier, the Sergeant took one look at the boat bobbing far beneath him, and declined Bruce’s invitation with considerable emphasis! So Boswell and John Wide gave a demonstration. After that there was no holding the American Army, who spent the rest of the afternoon hurling themselves off the pier. They enjoyed themselves so hugely that Boswell had some difficulty in persuading them to return to their base.
