The Challenge to Naval Supremacy
By John Hays Hammond, Jr.
[The Atlantic Magazine, October 1917]
In a letter to William Pitt, of January 6, 1806, relating to his invention of a submersible boat, Robert Fulton wrote prophetically, 'Now, in this business, I will not disguise that I have full confidence in the power which I possess, which is no less than to be the means, should I think proper, of giving to the world a system which must of necessity sweep all military marines from the ocean, by giving the weaker maritime powers advantages over the stronger, which the stronger cannot prevent.'
It is interesting to note that, about a hundred years later, Vice-Admiral Fournier of the French Navy stated before a Parliamentary committee of investigation that, if France had possessed a sufficient number of submersibles, and had disposed them strategically about her coasts and the coasts of her possessions, these vessels could have controlled the trade-routes of the world. He said also that the fighting value of a sufficient number of submersibles would reestablish the balance of power between England and France.
The history of naval warfare during the last few months has confirmed the opinions of these two authorities, although in a manner which they in no way anticipated.
Direct comparison is the ordinary method by which the human mind estimates values. We would measure the strength of two men by pitting them against each other in physical encounter; in the same way, we are prone to sure the combative effect of weapons by pitting them in conflict against other weapons. But modern warfare is of so complex a nature that direct comparisons fail, and only a careful analysis of military experience determines the potentiality of a weapon and its influence on warfare. Robert Fulton and Admiral Fournier both indicated that they believed in the submersible's supremacy in actual encounter with capital ships. The war, so far, has shown that, in action between fleets, the submersible has played a negative part. In the Jutland Bank battle, the submersible, handicapped in speed and eyesight, took as active a part, as a Jack Tar humorously put it, 'as a turtle might in a cat fight.' Not even under the extraordinary conditions of the bombardment in the Dardanelles, when the circumstances were such as lent themselves strikingly to submarine attack, did these vessels score against the fleet in action. [The Majestic was torpedoed at the Dardanelles, while at anchor. The Triumph was torpedoed while moving slowly; both war-ships had out their torpedo nets. THE AUTHOR.]
It is easy to understand why the submersible did not take a vital part in any of the major naval actions. In the naval battle of to-day we have a number of very high-speed armored craft fighting against each other over ranges extending up to 17,000 yards. There is a constant evolution in the position of the ships which it is impossible to follow from the low point of vantage of a periscope, for the different formations of ships mean nothing to the submersible commander. He is so placed that his range of vision is extremely limited, and, on account, of the low speed of his boat while submerged, he can operate over only a very limited area of water while the other vessels are moving many miles. Then, too, he is extremely vulnerable to the effect of enemy shells and to the ramming of enemy ships. Under these conditions, the submersible commander is more or less forced to a policy of lying ambushed to surprise his enemy. It is said that the Lusitania was decoyed into a nest of submersibles. There was but little chance of torpedoing her in any other way. There is also the statement that Admiral Beatty passed with his battle-cruisers through a flotilla of enemy submersibles without being touched.
Submersibles cannot attack their target in definite formations as do surface vessels, and therefore they cannot operate in numbers with the same effectiveness as the latter. They must manoeuvre more or less singly, and at random. Being limited to the torpedo, which, when they are submerged, is their sole weapon of attack, they have an uncertain means of striking their armed enemy. The eccentricities of the automobile torpedo are well known; but, even eliminating the fact that this missile is unreliable, the important question of accuracy in the estimate of range and speed which the submersible commander has to make before firing the torpedo must be considered. There is usually a large percentage of error in his calculations unless the submersible is extremely close to its target. Realizing these limitations, the German submersibles are equipped with small torpedoes, which are generally fired at ranges not exceeding eight hundred to two thousand yards. The necessity of approaching the target so closely is, of course, a tremendous handicap in the general operation of these boats. In view of these facts, it is not surprising that the submersible should not have been able to sweep the capital ship from the seas, as was predicted by certain experts before the war.h3 style="text-align: center">Part II
Admiral Sir Cyprian Bridge regards the functions of defense by a navy as divisible into three main classifications. He says, 'The above-mentioned three divisions are called in common speech, coast defense, colonial defense, and defense of commerce.' From this classification we are given a hint as to what a sailor means by 'naval supremacy,' 'freedom of the seas," and other terms so misused that to-day they mean nothing. 'Coast defense' means defense against invasion; 'colonial defense' means the safeguarding of distant possessions against enemy forces; the 'defense of commerce' means such supremacy on the seas as will insure absolute safety of the mercantile marine from enemy commerce-destroyers.
To-day every great nation is waging a trade war. The industrial competition of peace is as keen as the competition of war. All the great powers realized years ago that, to gain and keep their 'place in the sun,' it was necessary for them to construct navies that would insure to them a certain control of the seas for the protection of their commerce. In this way began the abnormal naval construction in which the powers have vied with one another for supremacy.
A simple way of looking at the question, what constitutes the power of a fleet, is to look upon the warship as merely a floating gun-platform. Even though this floating platform is the most complex piece of mechanism that was ever contrived by man, nevertheless its general function is simple. The war has given us enough experience to convince us that the back-bone of a navy is, after all, the heavily armored ship of moderately high speed, carrying a very heavy armament. This floating gun-platform is the structure best fitted to carry large guns into battle, and to withstand the terrific punishment of the enemy's fire. The battleship is today, notwithstanding the development of other types, queen of the seas. It is therefore not difficult to estimate the relative power of the fleets of different nations. In fact, a purely engineering estimate of this kind can be made, and the respective ranks of the world's naval powers ascertained. Germany has shown all through the war that she thoroughly appreciated British naval supremacy. Her fleet has ventured little more than sporadic operations from the well-fortified bases behind Heligoland. It was probably the pressure of public opinion, and not the expectation that she would achieve anything of military advantage, that forced her to send her high-sea fleet into conflict with the British squadrons off Jutland.
If one should examine the course of this battle, which has been represented by lines graphically showing the paths of the British and German fleets, one could easily see how the British imposed their will upon the Germans in every turn that these lines make. It reminds one very much of the herding of sheep, for the German fleet was literally herded on May 31, 1915, from 5.36 in the afternoon until 9 o'clock that night. Admiral von Scheer, however, fought the only action which it was possible for him to fight. It was a losing action, and one which he knew, from a purely mathematical consideration, could not be successful.
Through the very definiteness of this understanding of what constitutes naval strength, Great Britain's navy until recently has remained a great potential force, becoming dynamic for only a few hours at Jutland, after which it returned to that mysterious northern, base whence it seems to dominate the seas. Because of the potentiality of these hidden warships, thousands of vessels have traversed the ocean, freighted with countless tons of cargoes and millions of men for the Allies. Even at that psychological moment when the first hundred thousand were being transported to France, Germany refrained from a naval attack which might have turned the whole land Campaign in her favor.
To-day, however, the world is awakening to a new idea of sea-power, to a new conception that will have a far-reaching influence on the future development of naval machinery.
Sir Cyprian Bridge has stated that one of the functions of a fleet is the defense of commerce. There is no more important function for a fleet than this. A nation may be subjugated by direct invasion, or it may be isolated from the world by blockade. If the blockade be sufficiently long, and effectively maintained, it will ruin the nation as effectually as direct invasion. Thus, in the maintenance of a nation's merchant marine on the high seas, its navy exercises one of its most vital functions. There can, therefore, be no naval supremacy for a nation unless its commerce is assured of immunity from considerable losses through the attack of its enemy. It is idle for us to speak of our naval supremacy over Germany, when our navies are failing in one of their most important functions, and when our commerce is suffering such serious losses. The persons best qualified to judge are those who are most anxious regarding the present losses in mercantile tonnage.
While it has been shown that the submersible of to-day, as a fighting machine, is considerably limited, and in no sense endangers the existence of the capital ship, nevertheless in the new huge submersible it seems that the ideal commerce-destroyer has been found. This vessel possesses the necessary cruising radius to operate over sufficient distances to control important routes; it makes a surface speed great enough to run down cargo steamers, and has a superstructure to mount guns of considerable power (up to 6-inch). It embodies almost all the qualifications of the light surface cruiser, with the additional tremendous advantage of being able to hide by submergence. To be completely successful, it must operate in flotillas of hundreds in waters that are opaque to aerial observation. Germany has but a limited number of these submersibles, otherwise she would be able to crush the Allied commerce.
The ideal submersible commerce-raider should be a vessel of such displacement that she could carry a sufficient number of large guns in her superstructure to enable her to fight off the attack of surface destroyers and the smaller patrol craft. [The Germans have in operation submersibles of 2000 tons displacement. THE AUTHOR.]
She should be capable of cruising over a large radius at high speed, both on the surface and submerged. The super-submersible flotillas should comprise fifty or sixty of these units. The attack on the trade routes should be made by a number of flotillas operating at different points at unexpected times. To-day Germany has concentrated her submarine war particularly in the constricted waters about England. It is here that the shipping is most congested and therefore the harvest is richest, but it is also easier to protect the trade routes over these limited areas of water by patrols, nets, and so forth, than it would be to protect the entire transoceanic length of the steamship lanes. If the submersible were capable of dealing directly with the destroyer in gun-fighting, a tremendous revolution would take place in the tactics of 'submarine swatting.' Then it would be difficult to see how the submersible could be dealt with.
Improvement in motive machinery is the vital necessity in the development of the submersible. The next few years may see unexpected strides taken in this direction. A great deal will also be accomplished in perfecting methods of receiving sounds under water, particularly in relation to ascertaining the direction of these sounds. When this is done, it will be possible for the submersible commander to tell a great deal about the position of the vessels above him, and thus his artificial ears will compensate to a great extent for his blindness. By the addition of a greater number of torpedo-tubes, and the improvement of their centralized control in the hand of the commander at the periscope, along lines which we are now developing, it will be possible for the submersible to achieve a greater effectiveness in its torpedo fire. Probably torpedoes will then be used only against the more important enemy units, such as battleships, cruisers, and the like. To be certain of striking these valuable targets would be worth expending a number of torpedoes in salvo fire.
Whether the German U-boat campaign succeeds or not will be largely a question of the number of submersibles that the Central Powers can put into service, and to what extent the submersible will be developed during the present war.h3 style="text-align: center">Part III
German submarines have sunk over 7,250,000 tons of the Allied shipping. In December, 1916, it was stated in the British Parliament that the merchant marine of Great Britain had at that time over 20,000,000 tons. Within the first three months of the unrestricted submarine warfare, 1,100,000 tons of British shipping went to the bottom. At this rate, Great Britain would lose twenty-five per cent of her merchant marine per annum. It is for this reason that the attention of the entire world is concentrated upon the vital problem of the submarine menace. On land the Central Powers are still holding their ground, but there is a continuous increase of the forces of the Allies which should lead finally to such a preponderance of power as will overwhelm the forces opposed to them. The Allied armies, however, depend for their sustenance and supplies upon the freedom of the seas. The trade routes of the world constitute the arteries which feed the muscles of these armies. Germany is endeavoring to cut these arteries by the submarine. Should she even appreciably limit the supplies that cross the ocean to the Allies, she will bring about a condition that will make it impossible to augment their armies. In this way there will inevitably be a deadlock which, from the German standpoint, would be a highly desirable consummation.
Obviously, the first method of handling the submarine problem would be to bottle the German undersea craft in their bases. There has been a number of proposals as to how best to accomplish this. It has been stated that the British Navy has planted mines in channels leading from Zeebrugge and other submarine bases; but it is necessary only to recall the exploits of the E-11 and the E-14 of the British Navy at the Dardanelles to see that it would not be impossible for the Germans to pass in their U-boats through these ,mine-fields into the open sea. It will be remembered that the E-11 and the E-14 passed through five or more minefields, thence through the Dardanelles into the Sea of Marmora, and even into the Bosphorus, under seemingly impossible conditions. Yet, in spite of the tremendous risks that they ran, these boats continued their operations for some time, passing up as far as Constantinople, actually shelling the city, sinking transports, and accomplishing other feats which have been graphically described in the stories of Rudyard Kipling. And again, if the mine-fields were placed in close proximity to their bases, it would be comparatively easy for German submersibles of the Lake type, possessing appliances to enable divers to pass outboard when the vessel is submerged, to go out and cut away the mines and thus render them ineffective.
Nets also are used to hinder the outward passage of the submarine. These nets can in like manner be attacked and easily cut by devices with which modern U-boats are equipped. The problem of placing these obstacles is a difficult one, in view of the fact that the ships so engaged are harassed by German destroyers and other enemy craft. Outside of Zeebrugge, shallow water extends to a distance of about five miles from the coast, and it has been suggested that a large number of aircraft, carrying bombs and torpedoes, should be used to patrol systematically the channel leading from that port to deep water, with the intent of attacking the submersibles as they emerge from this base. It is ridiculous to suppose that the Germans would not be able to concentrate an equally large number of aircraft, to be supported also by anti-aircraft guns on the decks of destroyers and by the coast defenses. We have not yet won the supremacy of the air, and it must inevitably be misleading to base any proposition on the assumption that we are masters of that element.
The problem of bottling up the submersibles is enormously difficult, because it necessitates operations in the enemy's territory, where he would possess the superiority of power. I believe that the question of operations against the submarine bases is not a naval but a military one, and one which would be best solved by the advance of the Western left flank of the Allied armies. [1 Since this paper was written, we have seen with interest that this is the strategy of to-day.]
The second method is to attack the submarines with every appliance that science can produce. In order to attack the submarine directly with any weapon, it is necessary first to locate it. This is a problem presenting the greatest difficulty, for it is by their elusiveness that the submarines have gained such importance in their war on trade. They attack the more or less helpless merchant ships, and vanish before the armed patrols appear on the scene. Almost every suitable appliance known to physics has been proposed for the solution of the problem of submarine location and detection. As the submarine is a huge vessel built of metal, it might be supposed that such a contrivance as the Hughes induction balance could be employed to locate it. The Hughes balance is a device which is extremely sensitive to the presence of minute metallic masses in relatively close proximity to certain parts of the apparatus. Unfortunately, on account of the presence of the saline sea-water, the submersible is practically shielded by a conducting medium in which are set up eddy currents. Although the sea-water may lack somewhat in conductivity, it compensates for this by its volume. For this reason, the induction balance has proved a failure.
But another method of detecting the position of a metallic mass is by the use of the magnetometer. This device operates on the principle of magnetic attraction, and in laboratories on stable foundations it is extremely sensitive. But the instability of the ship on which it would be necessary to carry this instrument would render it impossible to obtain a sufficient degree of sensitiveness in the apparatus to give it any value. The fact that the submersible is propelled under water by powerful electric motors begets the idea that the electrical disturbances therein might be detected by highly sensitive detectors of feeble, electrical oscillations. The sea-water, in this case, will be found to absorb to a tremendous extent the effects of the electrical disturbance. Moreover, the metallic hull of the submersible forms in itself an almost ideal shield to screen the outgoing effect of these motors.
Considerable and important development has been made in the creation of sensitive sound-receiving devices to hear the propeller vibrations and the mechanical vibrations that are present in a submersible, both of which are transmitted through the water. There are three principal obstacles to the successful use of such a device: when the submersible is submerged, she employs rotary not reciprocating prime-movers, being in consequence relatively quiet when running under water, and inaudible at any considerable distance; the noises of the vessel carrying the listening devices are difficult to exclude, as are also the noises of the sea, which are multitudinous; finally, the sound-receiving instruments are not highly directive, hence are not of great assistance in determining the position of the object from which they are receiving sounds. [Big strides, however, have been made lately in overcoming these shortcomings, and it would appear that the principle of sound-detection is the most hopeful one for us to follow. THE AUTHOR.]
To locate the submersible, aerial observation has been found useful. It is particularly so when the waters are clear enough to observe the vessel when submerged to some depth; but its value is less than might be supposed in the waters about the British Isles and Northern Europe, where there is a great deal of matter in suspension which makes the sea unusually opaque. The submersible, however, when running along the surface with only its periscope showing, is more easily detected by aircraft than by a surface vessel. Behind the periscope there is a characteristic small wake, which is distinguishable from above but practically invisible from a low level of observation. Many sea-planes are operating on the other side for the purpose of locating enemy submersibles and reporting their presence to the surface patrol craft.
In order to overcome the disadvantages of creating the periscope wake which I have mentioned, it is reported that the Germans have developed special means to allow the U-boats, when raiding, to submerge to a fixed depth without moving. To maintain any body in a fluid medium in a static position is a difficult matter, as is shown in the instability of aircraft. One of the difficult problems of the submersible has been to master the difficulties of its control while maintaining a desired depth. The modern submersible usually forces itself under water, while still in a slightly buoyant condition, by its propellers and by the action of two sets of rudders, or hydroplanes, which are arranged along its superstructure and which tend to force it below the surface when they are given a certain inclination; but should the engines stop, the diving rudders, or hydroplanes, would become ineffective, and, because of the reserve buoyancy in the hull, the vessel would come to the surface.
In order to maintain the vessel in a state of suspension under water without moving, it would be necessary to hold an extremely delicate balance between the weight of the submarine and that of the water which it, displaces. Variations in weights are so important to the submersible that, as fuel is used, water is allowed to enter certain tanks to compensate exactly for the loss of the weight of the fuel. To obtain such an equilibrium, an automatic device controlled by the pressure of the water, which, of course, varies with the depth, is used. This device controls the pumps which fill or empty the ballast-tanks, so as to keep the relation of the submersible to the water which it displaces constant, under which condition the vessel maintains a fixed depth. The principle of this mechanism is, of course, old, and was first embodied in the Whitehead torpedo, which has a device that can be set so as to maintain the depth at which it will run practically constant. With the addition of a telescopic periscope, which can be shortened or extended at will, it will be possible for the U-boat to lie motionless, with only the minute surface of the periscope revealing her position.h3 style="text-align: center">Part IV
To attack the submersible is a matter of opportunity. It is only when one is caught operating on the surface, or is forced to the surface by becoming entangled in nets, that the patrol has the chance to fire upon it. Against this method of attack, modern submersibles have been improving their defenses. To-day they are shielded with armor of some weight on the superstructure and over part of the hull. They are also equipped with guns up to six inches in diameter, and, affording, as they do, a fairly steady base, they can outmatch in gun-play any of the lighter patrol boats which they may encounter.
One of the important improvements which have been made has resulted in the increased speed with which they now submerge from the condition of surface trim. A submersible of a thousand tons displacement will carry about five hundred tons of water ballast. The problem of submerging is mainly that of being able rapidly to fill the tanks. On account of the necessity of dealing with large quantities of water in the ballast system, the European submersibles are equipped with pumps which can handle eight tons of water per minute.
Again, the speed which the electrical propulsion system gives the vessel on the surface greatly increases the pressure which the diving rudders, can exert in forcing the submersible under water. This effect may be so marked that it becomes excessive, and Sueter emphasizes the point that vessels at high speed, when moving under water, may, on account of the momentum attained, submerge to excessive depths. To eliminate this tendency, there is a hydrostatic safety system which automatically causes the discharge of water from the ballast-tank when dangerous pressures are reached, thus bringing the submersible to a, higher level where the pressure on the hull will not be so severe. From this it follows that the opportunity of ramming a submersible, or of sinking it by gunfire, is greatly minimized, since the vessel can disappear so rapidly.
A great deal has been attempted with nets. Fixed nets extend across many of the bodies of water around the British Isles. Their positions doubtless are now very well known to the Germans. The problem of cutting through them is not a difficult one. Moreover, the hull of the submersible has been modified so that the propellers are almost entirely shielded and incased in such a way that they will not foul the lines of a net. There has also been a steel hawser strung from the bow across the highest point of the vessel to the stern, so that the submersible can underrun a net without entangling the superstructure. Some nets are towed by surface vessels. The process is necessarily slow, and to be effective the surface vessel must know the exact location of the submersible. Towing torpedoes or high explosive charges behind moving vessels has been developed by the Italian Navy, but the chances of hitting a submersible with such devices are not very great.
Bomb-dropping from aeroplanes can be practiced successfully under exceptional conditions only. In view of the fact that such bomb-dropping is exceedingly inaccurate, and that the charges carried are relatively small, this form of attack ordinarily would not be very dangerous for the submersible. Surface craft have also employed large charges of high explosives, which are caused to detonate by hydrostatic pistons upon reaching a certain depth. Patrol boats carry such charges in order to overrun the submersible, drop the charges in its vicinity, and by the pressure of the underwater explosion crush its hull. Since the pressure of an underwater explosion diminishes rapidly as the distance increases from the point of detonation, it would be necessary to place the explosive charge fairly close to the hull of the submersible to be certain of its destruction. To accomplish this, it would seem that the ideal combination would be the control of an explosive carrier by radio energy directly from an aeroplane. Thus we would have a large explosive charge under water, where it can most effectively injure the submersible, controlled by the guidance of an observer in the position best suited to watch the movements of the submerged target.
The third method by which to frustrate the attack of the submersible is to give better protection to the merchant marine itself. While a great deal of ingenuity is being concentrated on the problem of thwarting the submersible, but little common sense has been used. While endeavoring to devise intricate and ingenious mechanisms to sink the submersible, we overlook the simplest safeguards for our merchant vessels. To-day the construction of the average ship is designed to conform to the insurance requirements. This does not mean in any way that the ship is so constructed as to be truly safe. Thousands of vessels which are plying the seas to-day are equipped with bulkheads which are absolutely useless because they do not extend high enough to prevent the water from running from one part of the ship to another when the ship is partially submerged. Then again, the pumping system is so arranged as to reach the water in the lower part of the hull when the ship is up by the head. Should the ship be injured in the forward part and sink by the head, these pumps would be unable to reach the incoming water before her condition had become desperate. There is a vessel operating from New York to-day worth approximately a million dollars, and if she were equipped with suitable pumps, which would cost about a thousand dollars, her safety would be increased about forty per cent. Her owners, however, prefer running the risk of losing her to expending a thousand dollars!
If the merchant vessels were made more torpedo-proof, it would be an important discouragement to the U-boat commander. During the past two years of the war, nineteen battleships have been torpedoed, and out of this number only three have been sunk, showing that it is possible by proper construction to improve the hull of a ship to such an extent that it is almost torpedo-proof. While it may not be practicable, on account of the cost, to build merchant vessels along the lines of armed ships, nevertheless much could be done to improve their structural strength and safety; and since speed is an essential factor in circumventing torpedo attack, new cargo-carriers should be constructed to be as fast as is feasible.
So radically have conditions changed that to-day we have a superabundance of useless dreadnaught power. The smaller guns of some of these vessels, and their gun crews, would be far more useful on the merchant vessels than awaiting the far-off day when the German fleet shall venture forth again. The submersible must be driven below the surface by a superiority of gunfire on the part of the merchant marine and its patrols. In this way, the submersible would be dependent upon the torpedo alone, a weapon of distinct limitations. In order to use it effectively, the submersible must be not more than from eight hundred to two thousand yards from its target, and must run submerged at reduced speed, thus greatly lessening its potentiality for destruction. To-day submersibles are actually running down and destroying merchant vessels by gunfire. If merchant vessels carried two high-speed patrol launches equipped with three-inch guns of the Davis non-recoil type, and these vessels were lowered in the danger zone as a convoy to the ship, such a scheme would greatly lessen the enormous task of the present patrol. In the event of gunfire attack by a submersible, three vessels would be on the alert to answer her fire instead of one: an important factor in discouraging submersibles from surface attack!
The future of the submarine campaign is of vital importance. The prospect is not very cheerful. Laubeuf states that at the beginning of the war Germany had not over thirty-eight submersibles. This statement may be taken with a grain of salt; the Germans do not advertise what they have. It is probable, however, that to-day they have not more than two hundred submersibles in operation. Over four thousand patrol boats are operating against this relatively small number, and yet sinkings continue at an alarming rate. It is estimated that Germany will be able to produce a thousand submersibles in the coming year and man these vessels with crews from her blockaded ships. This will be a tremendous addition to the number she has now in operation. The greater the number of submersibles she has in action, the greater the area the submarine campaign will cover. The number of patrol vessels will have to be increased in direct proportion to the area of the submarine zone. Since a large number of patrol boats has to operate against each submersible, it will be seen that a tremendous fleet will have to be placed in commission to offset a thousand submersibles.
Thus the problem becomes increasingly difficult, and the protection of the trade route will be no more thoroughly effected than it is to-day—unless we overwhelm the enemy by a tremendous fleet of destroyers.
© J. Fred MacDonald, 2013
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THE HEADLONG FURY
A Novel of World War One
By J. Fred MacDonald