(2) On the approved date the "Catherine" Fleet would traverse the pa.s.sage by night or day, as judged expedient, using if desired smoke screens. The destroyers would sweep ahead of the fleet, the mine-b.u.mpers would precede the "Rs," and the cruisers and lighter vessels would follow in their wake. All existing apparatus of paravanes and other precautions can be added. It ought, therefore, to be possible to overcome the mining danger, and there are no guns to bar the channel. A heavy attack from the air must be encountered by the combined batteries of the Fleet.
Note: An aircraft carrier could be sent in at the same time and kept supplied with reliefs of aircraft reaching it by flight. An aircraft carrier could be sent in at the same time and kept supplied with reliefs of aircraft reaching it by flight.
PART III.
It is not necessary to enlarge on the strategic advantages of securing the command of this theatre. It is the supreme naval offensive open to the Royal Navy. The isolation of Germany from Scandinavia would intercept the supplies of iron ore and food and all other trade. The arrival of this Fleet in the theatre and the establishment of command would probably determine the action of the Scandinavian States. They could be brought in on our side; in which case a convenient base could be found capable of being supplied overland. The difficulty is that until we get there, they do not dare; but the three months" oil supply should give the necessary margin, and if the worst comes to the worst, it is not seen why the Fleet should not return as it came. The presence of this Fleet in the theatre would hold all enemy forces on the spot. They would not dare to send them on the trade routes, except as a measure of despair. They would have to arm the whole northern sh.o.r.e against bombardment, or possibly even, if the alliance of the Scandinavian Powers was obtained, military descents. The influence of this movement upon Russia would be far-reaching, but we cannot count on this.
Secrecy is essential, as surprise must play its full part. For this purpose the term "Catherine" will always be used in speaking of the operation. The caissons will be explained as "additional blisters." The strengthening of the turtle-deck is normal A.A. precaution.
I commend these ideas to your study, hoping that the intention will be to solve the difficulties.
W. S. C.
Appendix C, Book II
NEW CONSTRUCTION AND RECONSTRUCTION.
First Lord to First Sea Lord and Others.
October 8, 1939.
1. It is far more important to have some ships to fight with, and to have ships that Parliament has paid for delivered to date, than to squander effort upon remote construction which has no relation to our dangers!2. A supreme effort must be made to finish King George V King George V and and Prince of Wales Prince of Wales by their contract dates. The peace-time habit of contractors in booking orders and executing them when they please cannot be allowed to continue in time of war. Advise me of the penalties that may be enforced, in order that a case may be stated, if necessary, to the Law Officers of the Crown. Advise me also of the limiting factors. I suppose as usual the gun-mountings. It must be considered a marked failure by all concerned if these ships are not finished by their contract dates. I will myself inquire on Friday next into the condition of each of these ships, and will see the contractors personally at the Admiralty in your presence. Pray arrange these meetings from 5 by their contract dates. The peace-time habit of contractors in booking orders and executing them when they please cannot be allowed to continue in time of war. Advise me of the penalties that may be enforced, in order that a case may be stated, if necessary, to the Law Officers of the Crown. Advise me also of the limiting factors. I suppose as usual the gun-mountings. It must be considered a marked failure by all concerned if these ships are not finished by their contract dates. I will myself inquire on Friday next into the condition of each of these ships, and will see the contractors personally at the Admiralty in your presence. Pray arrange these meetings from 5 P.M P.M. onwards. It is no use the contractors saying it cannot be done. I have seen it done when full pressure is applied, and every resource and contrivance utilised. In short, we must have K.G.V. K.G.V. by July, 1940, and by July, 1940, and P. of W. P. of W. three months later. The ships we need to win the war with must be in commission in 1940. three months later. The ships we need to win the war with must be in commission in 1940.Pray throw yourselves into this and give me your aid to smooth away the obstacles.3. The above remarks apply also to the aircraft carriers. Ill.u.s.trious Ill.u.s.trious is to be five months late, and we know what that means. is to be five months late, and we know what that means. Victorious Victorious is even to be nine months late. is even to be nine months late. Formidable Formidable from the 1937 programme is six months late, and from the 1937 programme is six months late, and Indomitable Indomitable five months late. All these ships will be wanted to take part in the war, and not merely to sail the seas perhaps under the German flag (!) after it is over. Let me appeal to you to make this go. The later construction of aircraft carriers will not save us if we are beaten in 1940. five months late. All these ships will be wanted to take part in the war, and not merely to sail the seas perhaps under the German flag (!) after it is over. Let me appeal to you to make this go. The later construction of aircraft carriers will not save us if we are beaten in 1940.4. Thirdly, there are the cruisers. Look, for example, at the Dido, Dido, which was contracted to be finished in June, 1939, and is now offered to us in August, 1940. What is the explanation of this fiasco? which was contracted to be finished in June, 1939, and is now offered to us in August, 1940. What is the explanation of this fiasco?5. We have at this moment to distinguish carefully between running an industry or a profession, and winning the war. The skilled labour employed upon vessels which cannot complete during 1940 should, so far as is necessary or practicable, be shifted on to those that can complete in 1940. Special arrangements must be made as required to transfer the workmen from the later ships to those that are needed for the fighting. All ships finishing in 1941 fall into the shade, and those of 1942 into the darkness. We must keep the superiority in 1940.6. The same principles apply even more strongly to destroyers and light craft; but these seem to be going on pretty well, and I have not yet had time to look in detail into their finishing dates. But we most urgently require two new battleships, four aircraft carriers and a dozen cruisers commissioned and at work commissioned and at work before the end of 1940. before the end of 1940.W. S. C.
First Lord to First Sea Lord.
October 21, 1939.
I address this to you alone, because together we can do what is needful.We must have a certain number of capital ships that are not afraid of a chance air bomb. We have been able to protect them by bulges and Asdics against the U-boats. We must have them made secure against the air. It is quite true that it may well be a hundred to one against a hit with a heavy air torpedo upon a ship, but the chance is always there, and the disproportion is grievous. Like a hero being stung by a malarious mosquito! We must work up to the old idea of a ship fit to lie the line against whatever may be coming.To come to the point. I want four or five ships made into tortoises that we can put where we like and go to sleep content. There may be other types which will play their parts in the outer oceans; but we cannot go on without a squadron of heavy ships that can stand up to the battery from the air.I wrote you this morning about the Queen Elizabeth. Queen Elizabeth. But we must make at least five other ships air-proof, i.e., not afraid of a thousand-pound armour-piercing bomb, if by chance it should hit from ten thousand feet. This is not so large a structural rearrangement as might appear. You have got to pull a couple of turrets out of them, saving at least two thousand tons, and this two thousand tons has to be laid out in flat armour of six or seven inches, as high as possible, having regard to stability. The blank s.p.a.ces of the turrets must be filled with A.A. guns. This means going down from eight guns to four. But surely four fifteen-inch can wipe out But we must make at least five other ships air-proof, i.e., not afraid of a thousand-pound armour-piercing bomb, if by chance it should hit from ten thousand feet. This is not so large a structural rearrangement as might appear. You have got to pull a couple of turrets out of them, saving at least two thousand tons, and this two thousand tons has to be laid out in flat armour of six or seven inches, as high as possible, having regard to stability. The blank s.p.a.ces of the turrets must be filled with A.A. guns. This means going down from eight guns to four. But surely four fifteen-inch can wipe out Scharnhorst Scharnhorst or or Gneisenau. Gneisenau. Before the new German battleship arrives, we must have Before the new German battleship arrives, we must have King George V King George V and and Prince of Wales. Prince of Wales. Let us therefore concentrate on having five or six vessels which are not afraid of the air, and therefore can work in narrow waters, and keep the high-cla.s.s stuff for the outer oceans. Pull the guns out and plaster the decks with steel. This is the war proposition of 1940. Let us therefore concentrate on having five or six vessels which are not afraid of the air, and therefore can work in narrow waters, and keep the high-cla.s.s stuff for the outer oceans. Pull the guns out and plaster the decks with steel. This is the war proposition of 1940.How are you going to get these ships into dockyards hands with all your other troubles?Do not let us worry about the look of the ship. Pull the superimposed turrets out of them. Do one at Plymouth, one at Portsmouth, two on the Clyde, and one on the Tyne. These four-gun ships could be worked up to a very fine battery if the gunnery experts threw themselves into it. But, after all, they must bristle with A.A. and they must swim or float wherever they choose. Here is the war motif motif of 1940, and we now have the time. of 1940, and we now have the time.How all this reinforces our need for armoured ammunition ships, and armoured oilers, is easily seen. In all this we have not got to think so much of a sea action as of sea-power maintained in the teeth of air attack.All this ought to be put in motion Monday, and enough information should be provided to enable us to take far-reaching decisions not later than Thursday. On that day let us have Controller, D.N.C. and D.N.O. and shift our fighting front from the side of the ship to the top.* * * * *It looks to me as if the war would lag through the winter with token fighting in all spheres, but that it will begin with mortal intensity in the spring.Remember no one can gainsay what we together decide.W. S. C.
Appendix D, Book II
NEW CONSTRUCTION PROGRAMMES.
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Appendix E, Book II
FLEET BASES.
First Lord to D.C.N.S. and others.
1.II.39.
It was arranged at a conference between the First Lord, the First Sea Lord and the C.-in-C. on Nelson, October Nelson, October 31, 1939, that the following arrangements should be made at Fleet bases: 31, 1939, that the following arrangements should be made at Fleet bases:1. Scapa cannot be available, except as a momentary refuelling base for the Fleet, before the spring. Work is, however, to proceed with all possible speed upon(a) blockships in the exposed channels:(b) doubling the nets and placing them specially wherever required. They are to be at least as numerous and extensive as in the last war, plus the fact that the modern net is better. The routine of the gates is to be studied afresh with a view to briefer openings and greater security.(c) The trawler and drifter fleet on the scale used in the Great War is to be earmarked for Scapa, and its disposition carefully considered by Plans Division. However, all these trawlers and drifters will be available for the Forth until it is time to use Scapa as a main base, i.e., not before the end of February, 1940.(d) The work on the hutments is to proceed without intermission.(e) Gun platforms are to be made in concrete for the whole of the eighty guns contemplated for the defence of Scapa. The work on these is to proceed throughout the winter; but the guns will not be moved there or mounted until the spring, when everything must be ready for them.(f) The aerodromes at Wick are to be increased to take four squadrons.(g) The R.D.F. work is to be gone on with, but must take its turn with more urgent work.Meanwhile, Scapa can be used as a destroyer refuelling base, and the camouflaging of the oil tanks and the creation of dummy oil tanks should proceed as arranged. Staff at Scapa is not to be dimin ished, but there is no need to add to the oil storage there beyond the 120,000 tons already provided. The men now making the underground storage can be used for other work of a more urgent nature, even within the recent Board decision.2. Loch Ewe. Port A is to be maintained in its present position with its existing staff. A permanent boom and net is to be provided even before the Scapa nets are completed. The freshwater pipe is to be finished and any minor measures taken to render this base convenient as a concealed resting-place for the Fleet from time to time.3. Rosyth is to be the main operational base of the Fleet, and everything is to be done to bring it to the highest possible efficiency. Any improvements in the nets should be made with first priority. The balloons must be supplied so as to give effective cover against low-flying attack to the anchorage below the Bridge. The twenty-four 3.7 guns and the four Bofors which were lately moved to the Clyde are to travel back, battery by battery, in the next four days to the Forth, beginning after the Fleet has left the Clyde. It is not desired that this move should appear to be hurried, and the batteries may move as convenient and in a leisurely manner, provided that all are in their stations at the Forth within five days from the date of this minute. Strenuous effort with the highest priority for the R.D.F. installations which cover Rosyth must be forthcoming. Air Vice-Marshal Dowding is today conferring with the C.-in-C., Home Fleet, upon the support which can be forthcoming from A.D.G.B. The arrangement previously reached with the Air Ministry must be regarded as the minimum, and it is hoped that at least six squadrons will be able to come into action on the first occasion the Fleet uses this base.D.C.N.S. will kindly find out the upshot of the conference between the C.-in-C. and Vice-Marshal Dowding and report the results. We must certainly look forward to the Fleet being attacked as soon as it reaches the Forth, and all must be ready for that. Thereafter this base will continue to be worked up in every way until it is a place where the strong ships of the Fleet can rest in security. Special arrangements must be made to co-ordinate the fire of the ships with that of the sh.o.r.e batteries observing that a seventy-two-gun concentration should be possible over the anchorage.4. The sixteen balloons now disposed at the Clyde should not be removed, as they will tend to mislead the enemy upon our intentions.I should be glad if D.C.N.S. will vet this minute and make sure it is correct and solid in every detail, and, after obtaining the a.s.sent of the First S.L., make it operative in all Departments.W. S. C.
First Lord to First Sea Lord.
3.I.40.
Scapa Defences1. When in September we undertook to man the Scapa batteries, etc., the number of Marines required was estimated at 3,000. This has now grown successively by War Office estimates to 6,000, to 7,000, to 10,000, or even 11,000. Of course, such figures are entirely beyond the capacity of the Royal Marines to supply.2. Moreover, the training of the Royal Marines "hostilities only" men can only begin after March 1, when the necessary facilities can be given by the Army. Nothing has, in fact, been done since September except to gather together the nucleus of officers and N.C.O.s with about eight hundred men. These can readily be used by us either for the Marine striking force or the mobile defence force.The War Office, on the other hand, have a surplus of trained men in their pools, and seem prepared to man the guns at Scapa as they are mounted at the rate of sixteen a month. As we want to use the base from March onwards, it is certain that this is the best way in which the need can be met.3. If by any chance the War Office do not wish to resume the reponsibility, then we must demand from them the training facilities from February 1 and their full a.s.sistance with all the technical ratings we cannot supply; and also make arrangements for the gradual handing-over of the staff. It is clear, however, that the right thing is for them to do it, and we must press them hard.4. I do not wish the Admiralty to make too great a demand upon the Army. It would seem that the numbers required could be substantially reduced if certain tolerances were allowed. The figure of thirty men per gun and fourteen per searchlight is intended to enable every gun and searchlight to be continuously manned at full strength, night and day, all the year round. But the Fleet will often be at sea, when a lower scale of readiness could be accepted. Moreover, one would not expect the guns to be continuously in action for very prolonged attack. If these attacks were made, the Fleet would surely put to sea. It is a question whether the highest readiness might not be confined to a proportion of the guns, the others having a somewhat longer notice.5. Is it really necessary to have 108 anti-aircraft lights? Is it likely that an enemy making an attack upon the Fleet at this great distance would do it by night? All their attacks up to the present have been by day, and it is only by day that precise targets can be hit.6. When the Fleet is ready to use Scapa, we must shift a large proportion, preferably half, of the guns and complements from Rosyth. We cannot claim to keep both going at the same time on the highest scale. Here is another economy.7. It is suggested, therefore, by me that five thousand men should be allotted to the Scapa defences, and that the Commander should be told to work up gradually the finest show of gun-power he can develop by carefully studying local refinements which deal with each particular battery and post.8. For a place like Scapa, with all this strong personnel on the spot, parachute landings or raids from U-boats may be considered most unlikely. There is, therefore, no need to have a battalion in addition to the artillery regiments. The Commander should make arrangements to have a sufficient emergency party ready to deal with any such small and improbable contingencies.9. The case is different with the Shetlands, where we should be all the better for a battalion, though this need not be equipped on the Western-Front scale.W. S. C.
Appendix F, Book II
NAVAL AID TO TURKEY.
Note by the First Lord of the Admiralty.
November 1, 1939. 1, 1939.
The First Sea Lord and I received General Orbay this afternoon, and informed him as follows:In the event of Turkey being menaced by Russia, His Majesty"s Government would be disposed, upon Turkish invitation and in certain circ.u.mstances, to come to the aid of Turkey with naval forces superior to those of Russia in the Black Sea. For this purpose it was necessary that the anti-submarine and anti-aircraft defences of the Gulf of Smyrna and the Gulf of Ismid should be developed, British technical officers being lent if necessary. These precautions would be additional to the existing plans for placing anti-submarine nets in the Dardanelles and in the Bosphorus.We were not now making a promise or entering into any military engagement; and it was probable that the contingency would not arise. We hoped that Russia would maintain a strict neutrality, or even possibly become friendly. However, if Turkey felt herself in danger, and asked for British naval a.s.sistance, we would then discuss the situation with her in the light of the Mediterranean situation and of the att.i.tude of Italy with the desire to enter into a formal engagement. It might be that the arrival of the British Fleet at Smyrna would in itself prevent Russia from proceeding to extremities, and that the advance of the British Fleet to the Gulf of Ismid would prevent a military descent by Russia on the mouth of the Bosphorus. At any rate, it would be from this position that the operations necessary to establish the command of the Black Sea would be undertaken.General Orbay expressed himself extremely gratified at this statement. He said that he understood perfectly there was no engagement. He would report to his Government on his return, and the necessary preparatory arrangements at the bases would be undertaken.I did not attempt to enter into the juridical aspect, as that would no doubt be thrashed-out should we ever reach the stage where a formal Convention had to be drawn up. It was a.s.sumed that Turkey would ask for British aid only in circ.u.mstances when she felt herself in grave danger, or had actually become a belligerent.
Appendix G, Book II
THE BLACK-OUT.
Note by the First Lord of the Admiralty.
November 20, 1939. 20, 1939.
I venture to suggest to my colleagues that when the present moon begins to wane, the black-out system should be modified to a sensible degree. We know that it is not the present policy of the German Government to indulge in indiscriminate bombing in England or France, and it is certainly not their interest to bomb any but a military objective. The bombing of military objectives can best be achieved, and probably only be achieved, by daylight or in moonlight. Should they change this policy, or should a raid be signalled, we could extinguish our lights again. It should have been possible by this time to have made arrangements to extinguish the street-lighting on a Yellow Warning. However, so far as night-bombing for the mere purpose of killing civilians is concerned, it is easy to find London by directional bearing and the map, whether the city is lighted or not. There is no need to have the "rosy glow" as a guide, and it would not be a guide if it were extinguished before the raiders leave the sea. But there is not much in it anyway.2. There is, of course, no need to turn on the full peace-time street-lighting. There are many modified forms. The system in force in the streets of Paris is practical and effective. You can see six hundred yards. The streets are light enough to drive about with safety, and yet much dimmer than in time of peace.3. The penalty we pay for the present methods is very heavy: First, the loss of life; secondly, as the Secretary of State for Air has protested, the impediment to munitions output, and also work at the ports, even on the west coast; thirdly, the irritating and depressing effect on the people which is a drag upon their war-making capacity, and, because thought unreasonable, an injury to the prestige of His Majesty"s Government; fourthly, the anxieties of women and young girls in the darkened streets at night or in blacked-out trains; fifthly, the effect on shopping and entertainments.I would therefore propose that as from December 1:(a) Street-lighting of a dimmed and modified character shall be resumed in the cities, towns, and villages.(b) Motor cars and railway trains shall be allowed substantially more light, even at some risk.(c) The existing restrictions on blacking-out houses, to which the public have adapted themselves, shall continue; but that vexatious prosecutions for minor infractions shall not be inst.i.tuted. (I see in the newspapers that a man was prosecuted for smoking a cigarette too brightly at one place, and that a woman who turned on the light to tend her baby in a fit was fined in another.)(d) The grant of these concessions should be accompanied by an effective propaganda continuously delivered by the broadcast, and handed out to motorists at all refuelling stations, that on an air-raid warning all motorists should immediately stop their cars and extinguish their lights, and that all other lights should be extinguished. Severe examples should be made of persons who, after a warning has been sounded, show any light.4. Under these conditions we might face the chances of the next three winter months in which there is so much mist and fog. We can always revert to the existing practice if the war flares up, or if we do anything to provoke reprisals.W. S. C.
Appendix H, Book II
THE MAGNETIC MINE, 19391940 A Note on the Measures Against the Magnetic Mine Although the general characteristics of magnetic firing-devices for mines and torpedoes were well understood before the outbreak of war, the details of the particular mine developed by the Germans could not then be known. It was only after the recovery of a specimen at s...o...b..ryness on November 23, 1939, that we could apply the knowledge derived from past research to the immediate development of suitable counter-measures.
The first need was for new methods of mine-sweeping; the second was to provide pa.s.sive means of defence for all ships against mines in unswept or imperfectly swept channels. Both these problems were effectively solved, and the technical measures adopted in the earlier stages of the war are briefly described in the following paragraphs.
ACTIVE D DEFENCE M MINE-SWEEPING M METHODS The Magnetic Mine To sweep a magnetic mine, it is necessary to create a magnetic field in its Vicinity of sufficient intensity to actuate the firing mechanism and so detonate it at a safe distance from the minesweeper. A design for a mine-destructor ship had been prepared early in 1939, and such a ship was soon brought into service experimentally, fitted with powerful electro-magnets capable of detonating a mine ahead of her as she advanced. She had some success early in 1940, but the method was not found suitable or sufficiently reliable for large-scale development.
At the same time various forms of electric sweep were developed for towing by shallow-draught vessels; and electro-magnetic coils carried in low-flying aircraft were also used, but this method presented many practical difficulties and involved considerable risk to the aircraft. Of all the methods tried, that which came to be known as the L.L. sweep showed the most promise, and efforts were soon concentrated on perfecting this. The sweeping gear consisted of long lengths of heavy electric cable known as tails, towed by a small vessel, two or more of which operated together. By means of a powerful electric current pa.s.sed through these tails at carefully adjusted time-intervals, mines could be detonated at a safe distance astern of the sweepers. One of the difficulties which faced the designers of this equipment was that of giving the cables buoyancy. The problem was solved by the cable industry, in the first instance by the use of a "sorbo" rubber sheath, but later the method employed for sealing a tennis ball was also successfully adapted.
By the spring of 1940, the L.L. sweepers were coming into effective operation in increasing numbers. Thereafter the problem resolved itself into a battle of wits between the mine-designer and the mine-sweeping expert. Frequent changes were made by the Germans in the characteristics of the mine, each of which was in turn countered by readjustment of the mechanism of the sweep. Although the enemy had his successes and for a time might hold the initiative, the counter-measures invariably overcame his efforts in the end, and frequently it was possible to forecast his possible developments and prepare the counter in advance. Up to the end of the war the L.L. sweep continued to hold its own as the most effective answer to the purely magnetic mine.
The Acoustic Mine In the autumn of 1940, the enemy began to use a new form of mine. This was the "Acoustic" type, in which the firing mechanism was actuated by the sound of a ship"s propellers travelling through the water. We had expected this development earlier and were already well prepared for it. The solution lay in providing the minesweeper with means of emitting a sound of appropriate character and sufficient intensity to detonate the mine at a safe distance. Of the devices tried, the most successful was the Kango vibrating hammer fitted in a watertight container under the keel of the ship. Effective results depended on finding the correct frequency of vibration, and, as before, this could only be achieved quickly by obtaining a specimen of the enemy mine. Once again we were fortunate; the first acoustic mine was detected in October, 1940, and in November two were recovered intact from the mud flats in the Bristol Channel. Thereafter, successful counter-measures followed swiftly.
Soon it transpired that both acoustic and magnetic firing devices were being used by the enemy in the same mine, which would therefore respond to either impulse. In addition, many anti-sweeping devices appeared, designed to keep the firing mechanism inactive during the first or any predetermined number of impulses, or for a given period of time after the mine was laid. Thus, a channel which had been thoroughly swept by our minesweepers, perhaps several times, might still contain mines which only "ripened" into dangerous activity later. Despite all these fruits of German ingenuity and a severe set-back in January, 1941, when the experimental station on the Solent was bombed and many valuable records destroyed, the ceaseless battle of wits continued to develop slowly in our favour. The eventual victory was a tribute to the tireless efforts of all concerned.
Pa.s.sive Defence Degaussing It is common knowledge that all ships built of steel contain permanent and induced magnetism. The resulting magnetic field may be strong enough to actuate the firing mechanism of a specially designed mine laid on the sea bed, but protection might be afforded by reducing the strength of this field. Although complete protection in shallow water could never be achieved, it was evident that a considerable degree of immunity was attainable. Before the end of November, 1939, preliminary trials at Portsmouth had shown that a ship"s magnetism could be reduced by winding coils of cable horizontally round the hull, and pa.s.sing current through them from the ship"s own electrical supply. The Admiralty at once accepted this principle; any ship with electric power could thus be given some measure of protection, and whilst pressing on with further investigation to determine the more precise requirements, no time was lost in making large-scale preparations for equipping the Fleet with this form of defence. The aim was to secure immunity for any ship in depths of water over ten fathoms, whilst mine-sweeping craft and other small vessels should be safe in much shallower depths. More extensive trials carried out in December showed that this "coiling" process would enable a ship to move with comparative safety in half the depth of water which would be needed without such protection. Moreover, no important interference with the ship"s structure and no elaborate mechanism were involved, although many ships would require additional electric power plant. As an emergency measure temporary coils could be fitted externally on a ship"s hull in a few days, but more permanent equipment, fitted internally, would have to be installed at the first favourable moment. Thus, in the first instance there need be little delay in the normal turn-round of shipping. The process was given the name of "degaussing," and an organisation was set up under Vice-Admiral Lane-Poole to supervise the fitting of all ships with this equipment.
The supply and administrative problems involved were immense. Investigation showed that whereas the needs of degaussing would absorb fifteen hundred miles of suitable cable every week, the industrial capacity of the country could only supply about one-third of that amount in the first instance. Although our output could be stepped up, this could only be done at the expensce of other important demands, and the full requirements could only be met by large imports of material from abroad. Furthermore, trained staffs must be provided at all our ports to control the work of fitting, determine the detailed requirements for each individual ship, and give technical advice to the many local authorities concerned with shipping movements. All this refers to the protection of the great ma.s.s of ships comprising the British and Allied merchant fleets.
By the first weeks of 1940, this organisation was gathering momentum. At this stage the chief preoccupation was to keep ships moving to and from our ports, particularly the east coast ports where the princ.i.p.al danger lay. All efforts were therefore concentrated on providing temporary coils, and the whole national output of suitable electric cable was requisitioned. Cable-makers worked night and day to meet the demand. Many a ship left port at this time with her hull encased in festoons of cable which could not be expected to survive the battering of the open sea, but at least she could traverse the dangerous coastal waters in safety and could be refitted before again entering the mined area.
Wiping Besides the method described above, another and simpler method of degaussing was developed which came to be known as "wiping." This process could be completed in a few hours by placing a large cable alongside the ship"s hull and pa.s.sing through it a powerful electric current from a sh.o.r.e supply. No permanent cables need be fitted to the ship, but the process had to be repeated at intervals of a few months. This method was not effective for large ships, but its application to the great mult.i.tude of small coasters which constantly worked in the danger zone gave much-needed relief to the organisation dealing with "coiling" and yielded immense savings in time, material, and labour. It was of particular value during the evacuation of Dunkirk, when so many small craft of many kinds not normally employed in the open sea were working in the shallow waters round the Channel coasts.
Memorandum by the First Lord of the Admiralty.
15.III.40.
Degaussing of Merchant ShipsMy colleagues will be aware that one of our most helpful devices for countering the magnetic mine is the demagnetisation or degaussing of ships. This affords immunity in waters of over ten fathoms.The number of British ships trading to ports in the United Kingdom which require to be degaussed is about 4,300.The work of degaussing began in the middle of January, and by March 9, 321 warships and 312 merchant vessels were completed. Two hundred and nineteen warships and approximately 290 merchant vessels were in hand on the same date.The supply of cable, which has up to the present governed the rate of equipment, is rapidly improving; and it is now the supply of labour in the shipyards which is likely to control the future rate of progress.It would be a substantial advantage if part of the work of degaussing of British ships could be placed in foreign yards. The number of neutral ships engaged in trade with this country is about seven hundred. Neutral crews and in particular the crews of Norwegian ships are beginning to be uneasy about the dangers from enemy mines on the trade-ways to our ports. The importance to us of the safety of these neutral ships and of the confidence of their crews is a strong argument for disclosing to neutral countries the technical information which they require to demagnetise their ships which trade with this country.Against the substantial advantages of arranging for some British ships to be demagnetised in foreign yards and of extending demagnetisation to neutral ships must be set any disadvantages of a loss of secrecy. If the enemy is informed of the measures which we are taking, he may (a) increase the sensitivity of his mines, or he may (b) (b) mix mines of opposite polarity in the same field. If secrecy could be preserved, its advantage would be to delay these reactions of the enemy. But technical details of our degaussing equipment have had to be given to all ship-repairing firms in this country. Information which has been so widely distributed almost certainly becomes quickly known to the enemy. mix mines of opposite polarity in the same field. If secrecy could be preserved, its advantage would be to delay these reactions of the enemy. But technical details of our degaussing equipment have had to be given to all ship-repairing firms in this country. Information which has been so widely distributed almost certainly becomes quickly known to the enemy.Moreover (a) and ( and (b) have the disadvantages to the enemy that have the disadvantages to the enemy that (a) would make the mines easier to sweep and reduce the damage to non-degaussed ships by placing the explosion further forward or even ahead of the ships; and(b) reversal of polarity would only be effective against certain ships which are difficult to demagnetise thoroughly, and would also require a sensitive setting of the mine.The above position has altered since the arrival of the Queen Elizabeth Queen Elizabeth at New York and the subsequent publicity given to the subject in the press. The enemy now knows the nature of the protective measures we are taking and, knowing the mechanism of his own mine, it will not be difficult for him to deduce the manner in which degaussing operates. He can therefore now adopt any counter-measures within his power. The press notices have had the further effect of increasing demands for information from neutrals, and to continue to refuse such information conflicts with our general policy of encouraging neutral ships to trade in this country. at New York and the subsequent publicity given to the subject in the press. The enemy now knows the nature of the protective measures we are taking and, knowing the mechanism of his own mine, it will not be difficult for him to deduce the manner in which degaussing operates. He can therefore now adopt any counter-measures within his power. The press notices have had the further effect of increasing demands for information from neutrals, and to continue to refuse such information conflicts with our general policy of encouraging neutral ships to trade in this country.It is considered, therefore, by my advisers that we shall not be losing an advantage of any great importance by ceasing to treat the information as secret.The Admiralty recommend, therefore (i) that shipyards in neutral countries be used, if necessary, to supplement resources in this country for the degaussing of British merchant ships;(ii) that technical information of our methods of demagnetisation be supplied as and when necessary to neutral countries for the degaussing of neutral ships trading with this country.W. S. C.
Appendix I, Book II
EXTRACT FROM WAR DIARY OF U.47 U.47.
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On 29.11.39 the following entry was made in the war diary of Admiral von Doenitz: "Following the report that U.47 U.47 had torpedoed a cruiser, Propaganda claimed a sinking. From the service-man"s point of view, such inaccuracies and exaggerations are undesirable." had torpedoed a cruiser, Propaganda claimed a sinking. From the service-man"s point of view, such inaccuracies and exaggerations are undesirable."
Appendix J, Book II
CULTIVATOR NUMBER 6.
Note by the Author During these months of suspense and paralysis I gave much thought and compelled much effort to the development of an idea which I thought might be helpful to the great battle when it began. For secrecy"s sake this was called "White Rabbit Number 6," later changed to "Cultivator Number 6." It was a method of imparting to our armies a means of advance up to and through the hostile lines without undue or prohibitive casualties. I believed that a machine could be made which would cut a groove in the earth sufficiently deep and broad through which a.s.saulting infantry and presently a.s.saulting tanks could advance in comparative safety across No-Man"s-Land and wire entanglements, and come to grips with the enemy in his defences on equal terms and in superior strength. It was necessary that the machine cutting this trench should advance at sufficient speed to cross the distance between the two front lines during the hours of darkness. I hoped for a speed of three or four m.p.h.; but even half-a-mile would be enough. If this method could be applied upon a front of perhaps twenty or twenty-five miles, for which two or three hundred trench-cutters might suffice, dawn would find an overwhelming force of determined infantry established on and in the German defences, with hundreds of lines-of-communication trenches stretching back behind them, along which reinforcements and supplies could flow. Thus we should establish ourselves in the enemy"s front line by surprise and with little loss. This process could be repeated indefinitely.