The Gathering Storm: The Second World War (103 page)

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

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 circumstances, 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 assistance, we would then discuss the situation with her in the light of the Mediterranean situation and of the attitude 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 assumed that Turkey would ask for British aid only in circumstances when she felt herself in grave danger, or had actually become a belligerent.

Appendix G, Book II

THE BLACK-OUT

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 instituted. (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, 1939–1940

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 Shoeburyness 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 passive 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.

A
CTIVE
D
EFENCE
– M
INE
-S
WEEPING
M
ETHODS

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 passed 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.