The Defence of Harbours against Torpedo-Boat Attack

The transcript of a lecture delivered at the Royal Artillery Institution, Woolwich, Thursday, 12 November, 1903 by Fred T. Jane. Major-General F.G. Slade, C.B., R.A., Inspector-General of Royal Garrison Artillery, in the Chair.

Lecture

LECTURER: — Mr. Chairman, ladies and gentlemen, in venturing to address you upon this subject of defence against torpedo craft, I would desire at the outset to call your attention to the general obscurity that exists on the question. By this I mean not only the absence of data, but the absence of any, what I may call, "sealed pattern plan of defence."

I do not see how we could have one as things are, for we have very little to go on. The most that we can go on in the way of facts we may take from the Chino-Japanese War, which even if its results could be accepted as conclusive then, may be nullified now by the subsequent advent of the destroyer. However, let us first review the Chino-Japanese operations at Wei-hai-Wei.

There were altogether four attacks upon Wei-hai-Wei, and the defence consisted of 1 or 1½ iron steel hawsers with wooden floats every ten yards and a boom of this sort was placed at each entrance, but both booms had openings in them. The eastern entrance had two openings, there being one torpedo-boat one inshore protected by the forts that fell into the hands of the Japanese, and a larger one in the centre for big ships which was protected by mines, which the Japanese attempted to destroy, but only partially succeeded in doing. The forts guarding this entrance were already in the hands of the Japanese, and therefore from the gunners' point of view Wei-hai-Wei can hardly be regarded as any criterion whatever.

The points of interest about the attack worth noting are, that in the first attack of all, which was made on the 1st of February, when the Japanese boats came in they were sighted by the forts held by Japanese soldiers and fired at under the impression that they were Chinese boats. The boats then retreated untouched.

The second attack, which was made on the 2d of February, was again a failure, as the Chinese sighted the boats as they were coming into harbour. They again retired at once.

Then for the third attempt the scheme of attack was varied. A feint was made on one entrance by six boats, and the eastern entrance was attacked by twelve boats. It was an intensely cold night, there was no moon, it was about 3 o'clock in the morning. The Japanese lost two boats and one or two were very much damaged. Only one was hit by a 3-pdr. The forts did nothing. In fact the Chinese forts, so far as could be ascertained, did not see the boats until they were more or less amongst the big ships.

On the 4th, there was another attack, which was a complete surprise, in which they lost two boats from ship fire. So that practically we have really very little to go on, so far as torpedo-boat operations in a time of war are concerned.

All we may deduce I think from the Chino- Japanese affair is that the rule with the boats seems to have been, if once sighted and fired on, to retire at once and leave everything to the chance of getting in unseen on another occasion. boats have increased very rapidly and destroyers have multiplied exceedingly, Of course if this is to be the rule, defence will be a very easy thing, because a sharp look-out and a gun or two will be all that will be required. But we have to bear in mind the sort of attack, or what is likely to be the attack on us, may not be on similar lines to that which the Chinese met. I do not think we can assume that it would be the same. The Japanese were short of torpedo-boats and they could not afford to throw away what they had. Now-a-days torpedo-boats have increased very rapidly and destroyers have multiplied exceedingly, and I think we should take it for granted that if any attack is made, it will be pushed home as long as a single boat is left. Therefore the problem with regard to defence is to account for every single boat that attacks. Say, for instance, that twelve boats attack, it will not be much good accounting for eleven if one gets through.

There might be attacks made upon us the first night of a war when the enemy would hope to find things unarranged for, and later on when attack was unsuspected because of long immunity. It is of course extremely improbable that we should have a blockaded fleet, but we should very likely have one or two injured ships. Attack is pretty sure to be pressed home as torpedo-boats are so much more plentiful now and a few can easily be spent on an off chance.

The first question in relation to defence it seems to me is to find out what has got to be defended, whether the boats are coming with a view to securing any odd ship, damaged or otherwise, that may be in a harbour or whether their intention is to try to block up the docks and dock entrances by getting inside and torpedoing these. The latter perhaps is what we might be most in fear of and must expect to see attempted.

Then if we take the various defence systems, every system seems to have its advantages and disadvantages. If we take the favorite system, No. 1 gun firing at No. 1 boat, No. 2 gun firing at No. 2 boat and so on, that in theory may be a very excellent system, but the defect of it is that in practice, No. 1 boat becomes No. 3 perhaps at one moment and No. 2 at another, and there is always the danger that No. 1 gun may be firing at No. 2 boat, and No. 2 gun at it also, leaving one boat neglected, and a practice of rushing based on the chances given by this system exists, and, if one of a dozen gets through, untold mischief may be done.

There is also of course the question of what is to happen if more boats than guns should be used.

Then take the zone system. There success depends upon doing a great deal with comparatively small armaments. If the boats, knowing that the zone system is going to be employed, come in in bunches, then again there seems to be a very good chance of one boat managing to crawl through. If the boats would each enter each zone singly, their fates would be certain; but we cannot depend on that happening. Obviously the gun that has only one boat to fire at and the gun that has a dozen in its zone are very differently situated. Still, I incline to fancy that the zone system is better than any other. But whatever system of defence is adopted, there is always grave danger in a lack of definite co-operation between the Army and the Navy, and I think there can be no doubt that if the two forces fail to act in concert, it would tend to help and assist any attacking boats more than anything else.

As things are at present, we may assume, I think, that the shore defence would be entirely in the hands of the Army, but the Navy will, by having ships in the harbour, also be conducting some defence of its own.

This defence will perhaps include picket boats and if the attacking boats realize, as they very likely will do, that there is a picket boat defence, they may manage to take advantage of it, and either our picket boats may get destroyed under the impression that they are a hostile craft or the hostile craft may slip through as picket boats; but the subject of picket boat defence I shall allude to later on.

Next to gun fire, perhaps, search-lights form the most important part in all defence operations. The value of search-lights is I think a very debatable point. From my own experience on board torpedo-boats and destroyers rushing harbours, I think there is a great deal to be said both for and against the search-light. Of course for rushing in in peace time you are not firing any shotted guns, and therefore you cannot have any data to go on, as to how easy or difficult it may be for a destroyer coming in to fire at a search-light and perhaps pick it out, and then in the sudden gloom get in easily.

Some experiments in Germany seem to have shown that it is not a difficult thing to hit the search-light. My own impression of searchlights is that when you are three or four miles out, they do not show you up, but they do show the way in, and show it tremendously clearly. This is perhaps more true of fixed beams than of searching ones; the difficulty to the attack comes in where the searching beam gets full on the boat, inasmuch as then the boat can see next to nothing, and when the light goes away or is evaded there is a sort of complete blindness; I think that the value of the search-light for defence is perhaps to flash it on to the eyes of the boat's crew and then off again. Its use thus should lead very often to the boat going ashore or running into other boats from the temporary blindness that the flash has caused. The search-lights no doubt light the way in to some extent, so much so perhaps that the real value of them to defence is only the confusing effect they have on the attack. If the boats does evade the search ray it seems to me that it is not very likely to be picked up again, whereas if a deliberate flash system be adopted, there will be no need to bother about picking up. I am not sure that a good deal could not be done by a mechanically operated light. Exact experiments can hardly be carried out because of the danger involved in a really practical demonstration; but I may mention one walk in life in which a somewhat similar system is carried out tolerably scientifically and methodically. The ordinary policeman is often an adept in taking advantage of the impotence to which an assailant can be reduced by judiciously alternated light and darkness. I certainly think that something valuable might be evolved by regarding the searchlight as a weapon rather than as a substitute for daylight — its usual use.

In harbour attack I notice a boat has great difficulty in evading the search beams at all, but at sea I have certainly noticed that the boats manage to evade the beams very well, and I think that in war time a boat coming into harbour and trying to manoeuvre in order to evade the light would be manoeuvring differently to what it is in peace time; when the officers in command of the attacking boats do not care to run any unnecessary risk which is not warranted. But in war time where the question of retreat and attack comes in, I think a boat dodging about might possibly get out of the range of the searching beams and not be picked up again. In that case the searching beams would be to your disadvantage; but the great point altogether about the search-lights is that it seems very little thought has been devoted to the question of fighting search-lights with return lights. It was tried the other day at Portland when destroyers slipped in, and as soon as they were sighted switched their lights on to the forts and opened a heavy rifle fire on the men at the guns, and it is an interesting question as to what would happen in war time. This more or less unexpected rifle fire, coupled with the glare of the attack's searchlights, must have a very disorganizing effect on the defence for several minutes, say, for long enough to allow a certain proportion of the boats to slip through unhurt or nearly so.

The question that requires an answer is, how that sort of thing is to be met? Everything depends as I said before on the point—which is of more importance than anything else—that nothing must be allowed to get through. How to stop the boat getting through therefore becomes a doubly important problem. It is not so much that the boat has to be sunk, but it has got to be stopped from doing any mischief before it goes under.

Supposing a modern destroyer was hit by one 12-pdr shell, it is extremely improbable that that 12-pdr shell would sink her.

Then we will say that a foreign destroyer is attacking Portsmouth; supposing she gets up by Clarence Pier and she gets a 12-pdr shell into her, will that boat stop there or will she drift right on up harbour where she could ease off her torpedoes before she settled down for good.

That is why I think the Maxims might be an extremely useful adjunct to the defence, both alongside the 12-pdrs in the batteries and also where they are never put at all, that is at the entrance to the docks; so that supposing the boat is coming up, a Maxim fire can be directed on her sufficient to kill anybody at the tubes. The danger from the boat lies entirely with the men at her torpedo tubes, and to destroy the personnel in that case would be as good as destroying the boat.

Then the question with regard to booms is a very vexed one indeed. I believe the theory in the Navy is that the Navy can always jump the most ideal of booms; but in British harbours at any rate we cannot have those, for we must have ways for getting in fairly quickly and ways for getting out fairly quickly. This means entrances, and supposing these entrances to be only opened to let ships in or out, there is always the chance of an attack being made about that time.

We may assume that, supposing an attack to be made at all, one will very likely be made immediately war is declared or possibly a little before. The scouts which in the ordinary way might be lying off a harbour may not be out then, or they may be evaded. The theory animating the boats, certainly the one that animates the French torpedo flotillas, is that if they can only make their attack sufficiently early in the war they will come in at the time when everything is not quite ready — when perhaps the men are not all told off to their stations, and that they will get their chance to look in then, but quite as likely attacks might be expected several days after the war had commenced, when the first vigilance of the defenders had begun to slacken, especially in the early hours of the morning.

Supposing the booms to be an adjunct with a mine-field, the Chinese at Wei-hai-Wei had some mines, and it was reported on one occasion that some of these were exploded as the boats were passing, but the Japanese say that no damage whatever was sustained by them, and they rather had a theory that the mine would probably not hurt such a little thing as a boat rushing in. But whatever kind of mine is adopted, it may be taken for granted, I suppose, that the enemy will try and countermine, and if they countermine then it appears to me that there will be very great danger of the defence's attention being distracted by this countermining and possibly a certain amount of firing in that direction will be carried on by 'the enemy to secure a chance to make a second attack from some other point and so slip in.

Therefore perhaps the question might be gone into more than it is as to whether mines are or are not to be regarded as part of a harbour defence against torpedo craft, and, if so, whether a special kind of mine might not be served out to harbours intended solely to meet torpedo-boat attack. On the whole I fancy that the danger of distraction that countermining operations may afford, will render the mine defence a curse rather than a blessing to the defenders.

The submarine boat presents as grave a danger perhaps as any other form of attack. We are just beginning now to worry ourselves about submarine boat attack, and the question is how is it to be met? It will presumably have to be met by booms with nets below the surface in conjunction with a series of mines, but it is a very difficult problem. The gun is no good against submarines. The boat cannot very well be shot from the shore by any existing gun. The odds against hitting it are tremendous, even if it be awash; if it is coming in submerged, it is about a million to one that the periscope will not be hit; and even were it hit, the boat would still exist. It can still pop up and then disappear again. The first question that arises with regards to the best defence of a harbour against submarines is that it will probably need an exceedingly good and skilful commander to take a torpedo-boat up any harbour that we have. A thorough knowledge of the tides would hardly be his, the knowledge of the currents would not be his, and although he might possibly be able to do it in peace time, in war time, in the case of a submarine attacking a strange harbour under fire, we may, I think, rest assured that the probability is that it would get flurried. We might also be able to secure a boom with torpedo nets down below in which the boat would get caught up. But unless there is a certain amount of flurry and risk to the boat, I do not see what is to prevent the boat being armed with appliances to cut through the boom.

Or we might let the boat go cheerfully up inside the harbour and deal with it there. This would necessitate the employment of picket boats with spar torpedoes, but the spar attack against submarines does not seem to be altogether so successful as newspaper accounts make out. The submarines seem to be rather a difficult thing to stop in that way.

This question of submarine attack stands to be the problem of the future. What is to be done? Whatever device is thought of, anybody who has to do with submarines will waive it aside and say, "Oh, but submarines will get in." But even if we refuse to admit that to-day, although the submarine of to-day may be a defective weapon, the submarine of the early future will possibly be something very different indeed, and I do not see what we are going to do with the means for defence available at present.

I think this is a problem that will probably have to be left to the Navy to solve — this defence against submarine boats coming in. But as they would be more likely to attack the harbours with fleets in them than not, they would come under the Navy's province as things are at present.

That brings us back again to the old problem of divided control. My own theory is that the ideal arrangement would be that harbours should be absolutely defended by the Army or by the Navy, by one and not by the other, and in view of the fact that the Navy out at sea will be put to a tremendous strain in guarding against torpedo attack, the strain for instance of steaming full speed, and possibly the strain of battle, it appears to me to be exceedingly necessary that the Army should be able to guarantee absolute peace to it when coming into port. But the Army certainly is not likely to be able to guarantee that absolute peace if the Navy is carrying out one scheme on the water and the Army carrying out another ashore. If everything is left to the soldiers in regard to defence, then booms, mines and so on are much less likely to be sources of, I will not say disagreement, but of misunderstanding than as things are now.

I believe it is generally understood that if we go to war, there is likely to be a good deal of misunderstanding about mine fields, and I think that if the water inside a port or a harbour instead of belonging to the Navy belongs to the Army, we should be better able to guard against troubles of that sort. The alternative would be, supposing this Army control to be objected to, to have a certain number of harbours like Portland in which the defence was entirely left to the ships inside it, and bases like Portsmouth which would not have fleets lying in them, but docks and things of that sort to be defended, should be left entirely to the Army to control and defend. This would of course necessitate to a greater degree even than at present the study of each individual harbour, a knowledge of all its currents, its tides and shoals, all of which is best picked up by boating. I believe that there is a very good knowledge of most of our harbours on the part of many of the officers of the Garrison gunners which they have acquired by boating and they seem to be thoroughly acquainted with every shoal. In case of attack by hostile torpedo craft this knowledge should be invaluable to them, because they would know better then where to expect attack and be better prepared to meet it.

The second point would be to learn thoroughly the draughts of all probable enemies. Of course where there are we will say a hundred boats all drawing under 10 feet of water, it is not very much satisfaction to know that if twelve boats are attacked they are some of the hundred. But there are always a certain number of largish boats which cannot attack certain harbours. If all the draughts were known and studied, then the attacking force would be known or guessed at before it was properly seen and the defence could be conducted more satisfactorily.

Then I think it would be very necessary to study carefully what damage the enemy can do inside a harbour and guard against it. Say for instance what damage could an enemy do inside Portsmouth? He might run in perhaps at the western entrance or he might run in at the eastern, but supposing him to succeed in evading the guns there, and to get inside and come up the channel into the harbour where there is a very nasty twist, any hits in the steering gear of any boats coming up there would be extremely useful to the defence; but we might have another sort of harbour where the hitting of the steering gear would not be of any use whatever. Then supposing them to pass the Blockhouse at Portsmouth and to get inside the narrow part, what is to be done to them there, and who is to look after them if they do get there?

I have not heard myself who is to look after a foreign boat which does get inside Portsmouth harbour, whether it is to be left to the ships that may or may not happen to be lying there, or whether guns would be specially told off for the purpose. But certainly I do not think, from what foreign officers with whom I have conversed upon the subject say, that we have provided all the defence we might for a boat that does manage to get past and so get loose in the harbour. The boat would not reckon on coming out again, it would have done its work five minutes after it had got inside. The question is what is to be done with that boat when it is inside? The principal object of the defence when attack is being made, and when the boats are coming in, will be I take it, not so much to sink the boat as to stop her doing mischief. Sinking her of course is the surest way of dealing with her, but owing to the difficulty of sinking her at once it may be advisable to have a supplementary defence, and that is the reason I suggested the Maxims and Nordenfeldts. Suppose a new sort of Nordenfeldt, set up on end, and firing across a zone. If a boat were coming, say, with in a range it may be of 50 or 100 or 150 yards, and the Nordenfeldt were put the wrong way up as it were, one barrel would hit at 50 yards, one at 100 and the other at 150; and I think that if a gun of that sort were invented it would be rather an ideal weapon for the defence of harbours, and if several of these guns were placed at intervals which would make zones of fire through which every boat would be compelled to pass, a great advantage to the defence must be eHrcted. The guns on beyond would then be able to deal with anything that got through the zone of this fire, but the zone of fire from Nordenfeldt bullets and Maxim's on a destroyer or torpedo-boat, would be a very serious thing indeed. Supposing a Nordenfeldt bullet to got inside the engine room, it would do as much harm as a 12-pdr. A 12-pdr, of course would blow things about a great deal more but the boat would still have her way on her.

Now supposing her, instead of that one 12-pdr to be hit by ten or twenty Nordenfeldt bullets distributed about in various parts, of course we may ask ourselves which is going to do the more harm. We know she will ultimately sink from the effect of the 12-pdr hit, but what will she do before she sinks? Supposing one or two bullets to get into the engihes, the question is whether the total result of those or the accumulation of those may not be much more serious against the boat than the one put from the larger piece? The new British cruisers appear to be armed on an idea not altogether different to this. As I understand the latest cruisers are not to be fitted with the 12-pdr but with a larger number of 3-pdrs on the principle of getting more hits with less individual damage for isolated shots.

I think this matter of naval ingenuity should always be very carefully studied. Naval men are remarkably ingenious, and although the torpedo attacks we get, occuring as they do in times of peace, do not show it to the full, yet I think in time of war we should fully realize the great advantage that would accrue from a study of this very important branch of the subject of defence.

The case that I quoted of an attack on Portland where the boats stole up and when they were sighted, switched on their search-lights and then opened a heavy fire — that is the sort of thing that should be very much thought out I think, and we should ask ourselves what other little devices are there of that sort that boats might employ? I think we might find our ideal defence if the gunners were all sent out in the torpedo-boats and destroyers and the naval men were put in the forts. The gunners out in the boats would know all the weak points of the forts and the boats would be manoeuvred to come in in the best way against the forts, and that would furnish valuable data afterwards to know from what point the greatest danger might be expected, whereas the method in which the naval men conducted operations against the boats would possibly give a few valuable wrinkles that had not been thought of before. Naval men would naturally best understand what would be likely to damage boats very considerably.

I do not think that this kind of thing is likely to come about, but there have been steps in that direction, which I think everbyody should be extremely glad to see. Lately Garrison gunners have been out in torpedo-boats watching the attack, and from all I hear I think that seeing the thing from the other point of view has been of very great assistance indeed to those who will have to defend our harbours in war time. Being in a boat slipping in, and realizing the joy of slipping in which exists in the torpedo-boat, should enable the gunner to realize very fully indeed not only the ease or difficulty, as the case might be, of the slipping in; but the meaning of what a single boat out of a dozen slipping past would be.

It might be well to add that a combined attack is a thing that might very possibly happen; that is to say an attack we will say of 12 torpedo-boats or destroyers, supported by one or two cruisers, seizing a favorable moment. We will assume, for the sake of argument, that a British fleet is in the channel and that it goes in chase of a foreign fleet, and we will assume that this British and foreign fleet are in touch, the cruisers of either side operating together, cruising and scouting together, that is the time at which one or two cruisers attached to the hostile fleet might be detached in order to make a rash on a place like Portsmouth, where if the channel could be blocked up or the docks destroyed, incalculable mischief would result. If the torpedo attack were supported by cruisers, (of course we could not be sure that it would be—we may hope it would not be—but we cannot fail to recognize that such a thing is possible)and the cruisers came in and opened a heavy fire, under cover of which the boats could rush in, I think we should have an ideal attack from the attacking point of view. It is one which will be more dangerous than anything else, this attack of ships coming in unexpectedly with the object of creating a diversion, sending shells higgledy-piggledy about and round the forts, and then under the cover of the smoke and confusion torpedo-boats rushing in all of a heap, in the hope that one boat will get through, never mind what becomes of the rest. That, I think, is the form of attack that we must especially prepare for. In it there will always be danger; while any other form of attack will probably be doomed to failure. (Applause.)

Discussion

The CHAIRMAN: — I will now ask Admiral May if he will open the discussion with any remarks he may wish to make upon the lecture.

Rear-Admiral H.J. MAY, C.B.: — General Slade, ladies and gentlemen.

The point which, as a naval officer, I consider most worthy of discussion, is the general condition of an attack by torpedo-boats on a ship or ships in harbour.

We consider that when an attack is made on a ship or squadron at sea the odds are fairly balanced with regard to the chance of the boats succeeding, but immediately the ship gets into harbour the pendulum swings very greatly against the boats. First it is not easy to find a ship in harbour, she may get away into some corner where it is very difficult to see her, again she can get her nets out, she can have the shelter of a boom, and finally there are the garrison gunners on shore who will attack the boats as they come in. So that I do not think that the ordinary above-water boat is such a dangerous opponent to a ship in a fortified harbour as many people imagine, nor do I quite agree with what has been said on the question with reference to the dock gate. The dock gate is a very small thing, and it is a very easy matter to rig a raft or small boom with nets across the dock gate, when an attacking boat would find it a very difficult thing to get even its money's worth for the torpedoes fired out of an attempt made against a cassion thus protected. But conditions are changing; we have heard a little about submarine boats to-night, and we shall hear more in the future. Of one thing I am sure, that the above-water boat, with her big engines and her great vulnerability to guns, is not at all the best boat to use for the purpose of conducting an attack upon a ship at anchor where speed is not of great moment. The low speed of the submarine class of boat, which handicaps her at sea, is quite sufficient for carrying out an attack in harbour. But the submarine cannot be dealt with by guns from the shore. She must be met afloat, and that seems to me to be the pressing problem that has to be solved at the present time.

A year or two ago it was true that owing to the deadly fire of Q.F. guns it was quite unnecessary to have any guard boats afloat. But that day is gone, and under present day conditions with which our gunners have to deal, the defence will have to be much more afloat than it has been, and consequently there will have to be better cooperation between the Navy and the Army.

We have many instances in history of combined operations being carried on just on the edge of the shore. Those operations were usually successful when the Navy and the Army worked together harmoniously, but otherwise there was confusion and failure. When boats are used it is essential that the garrison gunners should be familiar with the officers in the boats and that the naval officers should frequently go ashore to the batteries. There must also be complete harmony between the commanding officers, and then things will go well. It may be that changes in organisation are desirable to promote the working in unison of the two services, but what we have got to see to at the present time is, when we are righting together on the edge of the water, some being on shore and some afloat, that whatever we call ourselves, being all the King's officers, we must work together harmoniously.

With regard to the question of the guns on shore for opposing boats. The 12-pdr does not altogether commend itself to me as the most satisfactory defence weapon. A gun is wanted that will quickly stop a boat, and for this purpose a high explosive shell is the best projectile. But the 12-pdr cannot fire lyddite. An ordinary powder shell hitting a boat high up, passing through the funnel or upper works will do no harm at all. But a lyddite shell detonating on funnel or venilator, will stop the boat. The cruisers mentioned by Mr. Jane have 6-inch guns as well as 3-pdrs and it is the former gun that is most deadly. The 4.7-in gun is a very good gun, and though such guns are big and expensive, there is much in their favour, especially when combined with 3-pdrs or Maxims for attacking the exposed officers and men on deck. As long as people in the torpedo