COAST DEFENCE

the war of 1914-8 has natu- rally caused changes in the realm of coast defence, as it has in every branch of the military art. effect of new weapons opinions have been expressed to the effect that great britain’s whole scheme of coast defence must be changed, owing to the introduction of new weapons, of which by far the most promi- nent is the use of aircraft. against this it is contended, on gen- eral principles first of all, that history has shown that a new weapon has never caused a revolution in the art of war. natu- rally a new effective weapon will cause a change; and the intro- duction of aircraft has caused a change, but it is not a revolution. it will be found that the new weapon or the fresh invention takes its place in the armoury of war alongside of, but not at first, and sometimes never, in place of what has gone before. before dealing with this suggested fundamental change it will be well to glance at the occasions on which coast defences were brought into play during the world war. these were not numerous. practically the first one was the german raid on the york- shire coast on dec. 16 1914. during this the ‘ seydlitz,” ‘ molt- ke’ and “ bliicher,’”? mounting 64 guns altogether, from 11-in. down to 6-in. bombarded hartlepool for nearly an hour. the only guns on shore were three 6-inch. of course a large number of casualties were caused among the civil population, but no damage was done to the shore battery or its garrison of durham terri- torial artillery. later on the germans admitted the loss of 10 killed on the “ bliicher,” while it was plainly visible that the upper works of the ships were suffering from the battery’s fire, which was sufficiently annoying to draw off the enemy’s atten- tion from a small naval vessel which had emerged from the har- coast defence bour and had been suffering loss. during the war a long series of engagements took place between british ships and the nu- merous batteries erected by the germans on the belgian coast. admiral bacon’s book on the dover patrol mentions at least 4o of these engagements, and yet no gun, mounting or magazine of these batteries was ever hit. dardanelles and zeebrugge.—in the naval operations in the dardanelles, on march 18 1915, a deliberate action was fought between the main batteries of the turks at the narrows and 16 british and french battleships at the comparatively short ranges of from 14,000 lo 10,000 yards. the turkish batteries and guns were old, their sites were ill-chosen, as a rule close to the water, and their high traverses and deep embrasures rendered them very conspicuous. the batteries were, however, helped by the existence of mines, the position of which was imperfectly known to the ships. at the end of the day three battleships had been sunk by mines, and three others so badly damaged by shell fire as to necessitate their immediate withdrawal to a dockyard. the damage to the batteries was very small. for instance, the ilamidieh i. battery near chanak, which contained three 14-in. and six g-2-in. guns, had one of the latter put out of action and suffered some losses in its garrison. a war-time battery of five 6-in. guns at dardanos, skilfully sited near the top of a conspic- uous hill some 150 ft. high and in advance of the narrows, re- ceived a large amount of attention from the fleet, not only dur- ing the main action, but for some days previously, but the only result was that splinters made three dents on the gun-shields. the most spectacular action of the war between ship and shore was the successful blocking of the bruges ship canal on april 23 1918 by sir roger keyes’s ships. this operation had been tried at santiago de cuba by the americans and several times at port arthur by the japanese; in both cases the attempts were unsuccessful. the success at zeebrugge is an excellent in- stance of the fact that a fleet which is fully determined to come to close quarters with coast defences will most surely find out any weak spots. and there were weak spots at zeebrugge. most of the german guns were sited as if they were meant to defend the water outside the mole and none seemed to have been allotted to deal specifically with block-ships, although the germans quite realised the possibility of such an attack. the search lights especially were poorly sited; there was no concentration of illumination at the zone where the guns would have been most effective. on the other hand, the flanks of the canal entrance were crowded with machine-guns, trench-mortars and _ riiles. these weapons were useless for stopping the ships themselves, but were admirably placed for killing the crews, especially when the latter were leaving the ships. that the losses among the crews of block ships and motor boats were small can only be put down to the theory that ‘‘ fortune favours the brave.” value of aircraft-—-coming now to the action during the war of aircraft in the realm of coast defence the instances are few, and practically none are recorded of such action against coast defences. attempts were made to bomb the ‘‘ goeben ”’ in jan. 1918, when she made a sortie and grounded on nagara point, remaining there for six days, but the results were prac- tically nil, as she was only once hit, on a funnel, in a series of over 200 flights. there was also the case of the german cruiser ‘‘ kenigsberg,” jaid up in a river in east africa. she was bombed by two sea- planes, one of which was brought down by her gunfire and the other of which did her no harm. the ship was finally destroyed by indirect gunfire from two monitors, the fire being controlled by seaplane observation. admiral sims, in his book victory at sea, recalls the fact that although the u.s. navy had soo planes, a large number of which were operating over the north sea, irish sea, bay of biscay and the adriatic against submarines, only one boat was destroyed by direct bombing and one was ‘““ probably damaged.” in action against a ship, aircraft are heavily handicapped compared with a gun ashore. aircraft really provide a form of long-range bombardment, in which the aircraft’s engines take the place of the propellant charge in the gun. but every bomb coast defence that is dropped is a trial shot and no information gained from the first bomb is of any use for correcting the dropping of the next. no gun commander, ashore or afloat, expects a hit with his first shot, but he uses it to correct the fire of his next. but with aircraft, every bomb is a “ first shot.”’ there is no inten- tion here of decrying the value of aircraft in its main sphere of observation; the only contention is that aircraft cannot take the place of artillery in coast defence. deliberate trials have taken place since 1918 to ascertain the effect of aircraft against ships. the most important of these were made in the united states in 1921. two old warships, the “ new jersey ” and the “ virginia,’ were anchored and exposed to aerial attack. although 75 planes were used against them it was 93 hours before the ships were sunk. other trials have been made, but the results were no more favourable to the aircraft. since the war, aircraft have been designed to carry torpedoes for the attack of ships and great results have been expected from them. hitherto they have been in the trial stage only, but they have the disadvantages that they must descend to from 10 to 15 ft. from the water before releasing their torpedoes and must get within some 1,000 yards of their target, thus rendering them- selves peculiarly vulnerable to every kind of fire from a ship. taking into account all the experiences gained in the late war, and fully weighing what aircraft can do in their present stage of evolution, it is firmly contended that the basic principles under- lying the british idea of coast defence before the war are still thoroughly sound, and that, it is correct policy to regard the gun as the main weapon for use now against an enemy’s fleet. guns and batteries on the assumption that the gun is still the main weapon of coast defence, it will be well to consider in what way the differ- ences of the conditions under which the shore gun and the naval gun carry out their work have altered since 1914. (1) the fact that ranges have greatly increased has affected the question in several ways: — (a) the handicap against the naval gun, in being on a platform which is not immovable, has been accentuated, since the longer the range the greater will be the distance any movement of the ship, however small, will throw the shell off its intended target. (5) guns are not mathematical instruments. their shooting is affected by very slight variations of propellant charge in quality and quantity, of weight of projectile, of the distance by which the latter is rammed home in the bore, and by the wear of the gun itself, not to speak of change of atmospheric conditions. increased range magnifies the inaccuracies caused by these factors and necessitates a greater number of rounds being fired to produce a given effect than was the case with shorter ranges. the amount of ammunition ina ship, especially for heavy guns, is not large, and it is far less easy to replenish this afloat than it is for the gun ashore with all the resources of the land. (c) increase 1 ranze is more helpful in rendering a shore gun incon- spicuous than it is as regards a ship. probably, too, heavy guns will be sited behind low hills so that they are invisible from the sea. (2) the methods ailopted and under trial for range-finding and the control of fire have made greater advances ashore than afloat. this is owing to the inherent inferiority of ships in this respect, com- pared with guns as‘9re, since all arrangements to this end are re- stricted to the dimensions of the ship and its masts, whereas the shore gun has the whole coast within the limits of vision at its dis- posal and will often have the advantaze of using commanding heights. in this connection, too, the shore gun may be able in the future to make use of sound-ranging, which proved so useful on land in the world war. this would be especially valuable for dealing with a ship which protected itself by a smoke screen, this form of ranging is denied to a ship, since a long base is necessary. aerial observation.—both sides can make use of aerial obser- vation of fire, but, in addition to the use of smoke screens, which is also available to both, it will be possible to take other steps to render the elements of a coast battery indefinite objects when regarded by the eye of an aerial observer. this is a measure which is impossible to a ship which, apart from smoke screens, must always be a well-defined object on a flat surface. as re- gards aerial observation, the possibilities of jamming the wireless of spotting aircraft by either contestant have not yet been fully explored. the americans have done some experiments in this direction and, if this should prove possible, the value of aerial observation would largely disappear. 665 it may be argued that if ships find that, in the attack of coast defences, they are too greatly handicapped by long ranges they will close in to shorter ranges and endeavour to overwhelm bat- teries by their superior volume of fire. this manoeuvre, how- ever, would be the means of giving the superior instrumental system of control of fire possessed by the shore gun the very chance of proving that superiority, as it is at the very long ranges that all instrumental observation, ashore and afloat, is weakest. and shorter ranges would give hghter guns their opportunity. at present (1926) there seems a disposition to ignore the damage that can be done by medium and light guns to heavy ships, but the fighting efficiency of a ship can le greatly impaired without penetrating its armour. so that it is quite possible that this view is overdone. the 6-in. guns at hartlepool were hope- lessly outclassed in number and size ly those of the german, yet they took their toll of their powerful opponents and came off scatheless. the dispatches of the admiral in command during the dardanelles operations often refer to the great annoyance caused to his ships, armoured and otherwise, by two 6-in. bat- teries, messudieh and dardanos, while admiral lord wester wemyss, in his book, refers to the “ prince george,” an old battleship, being hit by a 6-in. shell, taking a list and having very shortly to be withdrawn to a dockyard on account of the damage clone. size of guns—the heaviest british pre-war gun was the q:2-in., firing a 380 |b. projectile to a range of some 17,000 yards. it is now necessary to have a longer range weapon. to obtain this it is not really essential to have a gun of rruch larger calibre, although the life of a large long-range gun is longer than that of a smaller one of equal range. but against capital ships now it is necessary to have a projectile with greater power than that of the 9:2-in. and such guns as the 12-in. or upwards are required. it has often been advocated that guns on railway mountings should be used for coast defence,! as they can be moved from place to place as the situation demands, while their appearance would be unexpected. but the railway mounting is most un- suitable for use against moving targets since it does not give sufficient traverse, as it can be fired only a few degrees off the axis of the railway. for larger variations a railway gun has to be on a curve and move along it as required to alter the line of fire. this is much too slow for coast defence purposes. also, modern arrangements for control of fire demand fixity of posi- tion, while from the point of view of training the detachments, especially with local forces, it is vital to have the gun always on the spot. finally, a railway mounting is more expensive than a fixed one. for these reasons its use is not advocated. design of baticries—as regards heavy guns, when the long ranges now required are considered and the great improbability that ships will come close in, there are many advantages to be gained by siting the guns behind features of the ground, so that they are unseen altogether from the sea. in any case, such guns would have to be controlled by some form of position-finding instruments, so that nothing is lost in this way. the advantages gained are increased protection from hostile fire, much greater latitude in choice of sites and probably easier communications up to the battery. the disadvantages are a small loss of range, an area of dead water owing to the shell having to clear the inter- vening higher ground and the difficulty of fighting the guns if the communications of the control of fire system be damaged. the loss of range is generally immaterial, the dead-water, even assuming that it is navigable, can generally be covered from another battery, while adequate protection for the communica- tions, with possibly their duplication, would reduce the third disadvantage toa minimum. all the heavy german guns on the belgian coast were sited for indirect fire. the actual design of batteries can be considerably simplified. in this the guiding principles may be said to be that everything tthe ordnance department, u.s. army, has designed railway mounts (the largest being for a 14-inch gun of approximately 40,000 yards range) in which this difficulty has been overcome. the design permits of rapid emplacement on a prepared base and ensures the same all round traverse, and speed and accuracy of fire, as obtain for the gun on a fixed mount. (ed. £.8b.) 666 must be done to facilitate the service of the guns, while protec- tion from hostile fire will be sought for by dispersion of the vul- nerable points, e.g., magazines, and not by giving them thick material cover. the guns will still require their solid concrete platforms, but parapets are unnecessary. ammunition will be distributed in small expense stores at some distance apart, and these will not be shell-proof but only weather-proof and splinter- proof. it will be useless for a ship to aim at a battery as a whole; each element of it, gun or expense store, will form a separate target. batteries for use against cruisers and light craft, mounting medium and light guns, say g-2-tn. and 6-in., will still be sited for direct fire, and so will be visible from the sea. the same guiding principles will apply to them as in the case of the heavy batteries, except that special care must be taken to render them difficult targets for ships at sea. the guns must have a background close behind them and the ways of communication, from the ammuni- tion stores up to the guns, must be kept out of view from the sea, as well as the stores themselves. air attack.—the war introduced this new feature which must be reckoned with. as already mentioned, aircraft can and will be used for controlling the fire of both shore and ship guns. but aircraft can also act offensively against coast defences by dropping bombs. the best protection of batteries against aerial attack will be in the use of counter aircraft and of anti-aircraft guns. even with the latter only—and their action is becoming more and more effective—hostile aircraft will have to keep high up and the accuracy of their aim in bombing will thus be greatly impaired. the largest vulnerable element of a coast battery will be the gun and its emplacement, which will not exceed 20 yd. diameter with the heaviest guns. if an aeroplane were travelling at a speed of 120 m.p.h., in order to get a direct hit on the emplace- ment the bomb must be released at an exact third of a second, and if there is any wind this must be allowed for. these condi- tions are very difficult to fulfil conjointly, but practically direct hits are necessary to put out of action any of the elements of a battery, whether guns or stores. it is also easy to erect traverses round the vulnerable elements which would guard against bombs dropping close by. as a rule, every battery will be within the region of anti-aircraft guns. land altack.—this has very often been the most effective form of attack on a coast fortress, but it is a branch of land war- fare and cannot be dealt with here. bibliography.—sir g, clarke, fortification (1907); capt. a. t. mahan, naval strategy, etc. (1912); capt. a. p. s. hyde, attack and defence of fortified itarbours (1914); col. g. j. fiebeger, per- manent f ortifecation, etc., (1916); capt. j. avice, la de an des froniieres maritimes (1922). 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