A great desideratum in building up a fighting fleet is economy in the expenditure of money and men. It is hardly to be expected that all such expenditures could be so made that all are represented in a general action, and one measure of the efficiency of a fleet is the percentage of the total expenditures that are then available.
There will always be special classes of vessels used for special purposes, which cannot be used for fighting, in a fleet action, and they will require men that are therefore not used in battle. There are, on the other hand, vessels that will always be valuable in a general action, such as the battleship, the destroyer, and the submarine—real fighting ships—and we might say that their crews are fighting men. How many of the others though are non-combatants?
Are cruisers fighting ships? To be sure, a cruiser will fight a cruiser or a vessel inferior to herself, but she is wasted capital in a general action, as she cannot inflict damage on a capital ship. The same may be said, to a large extent, of the battle cruiser; indeed it might be asked, is the battle cruiser intended to fight in a general action?
This is usually answered in the affirmative, and it is probable that the first intent was that the battle cruiser should be employed in a general action as a battleship, though of course in a special organization, such as a fast wing. That this is, however, the present idea, is to be doubted, and that such ships, in action, can be considered as anything more than inferior battleships is open to question.
Cruisers have always been required for purposes other than use in ,a fleet action, and even in the days of wooden ships, when the only essential difference between the type used for fighting and the type used for cruising was a matter of size of ship and numbers of guns, the cruiser type was used strictly for the special work of its type, and was rarely employed in a general battle. It is likely, however, that this was due more to the fact that sufficient numbers of the type were never available, rather than to an idea that the type was unsuitable for fighting.
Modern cruisers, even the battle cruiser, differ in a much greater degree from the type that has been accepted as the most suitable for fighting in a general action, and it can hardly be denied that in an engagement of battleships the cruiser type, as exemplified by the modern scout, and to a less degree by the battle cruiser, could not be used for heavy work.
It becomes then a question how much money we can afford to spend for a type of ship that should be on hand in considerable numbers, and yet is not available to be drawn into the line of battle for work against the main body of the enemy fleet. In the long run, it always means that money, expended on such ships means less money available for fighting ships.
It seems hardly necessary to argue that if all the ships used for scouting and screen purposes could also be effectively used in action against capital ships, their value would be greatly enhanced, and money expended to build them would be not only more wisely expended, but also more easily obtained.
Let us therefore examine into the reasons why the present ships of these classes are not fit for fighting capital ships, and see if some method cannot be suggested to overcome the handicap under which they fight.
The scout cruiser need hardly be investigated at all, since its weaknesses in action are well known. With no protection at all against the battery of a battleship, this vessel also lacks offensive power suitable for use against a capital ship. Its 6-inch battery need not be expected to make any impression on a capital ship, even at short range, and at long range it could not even reach.
With the battle cruiser the question is not so easily answered, although demonstration is not difficult. This vessel cannot be pitted against a battleship of her own date at close range, since she has insufficient protection against a battleship battery at short distances. Even under the most favorable circumstances the 5-inch belt will fail to keep out a 14-inch projectile, and the ship might, therefore, at short ranges, say up to 10,000 yards, be considered entirely unarmored, as far as a battleship battery is concerned.
It is also to be considered that the battle cruiser lacks a sufficient number of guns to fight on equal terms a battleship of her own date, and it will hardly be argued that she will nevertheless be useful against older ships. That is not the aim of naval design.
When we consider fighting at long range, the battle cruiser is not so hopelessly outclassed, though still, on account of the less numerous battery, at a disadvantage. Before going farther, it will be well to define the term long range. It might well be that at, say, 15,000 yards the armor of a battle cruiser will be relatively more effective; that is, the 5-inch belt will keep out a greater proportion of 14-inch projectiles at that range than it would at short range. On the other hand, the battleship armor also gains in effectiveness at such a range, and it can still be said that as compared to the battleship the battle cruiser is unarmored.
There is, for any kind of gun, a range at or beyond which the angle of fall is so large as to make a glancing blow on an armored deck practically impossible. This angle may be 30°, or it may have to be as great as 45°. Then, if the gun has a sufficiently large caliber, penetration of the armored deck becomes possible upon a hit being obtained. It might be stated as a general proposition that for the calibers used nowadays and for the decks as at present fitted such penetration is practically sure with angles of fall of 30° or more. With angles of fall between 15° and 30°, penetration is more or less uncertain, and below 15° practically impossible.
If, then, we consider as long ranges those at which penetration through the armored decks becomes easily possible, when a hit is obtained, such ranges, with guns now used, must be more than, say, 16,000 yards, and in most cases must be well over 20,000 yards.
At such long ranges, the battleship is reduced to equal terms with the battle cruiser, as far as the decks are concerned, assuming that considerations of weight have made it impossible to give the cruiser the same weight of decks as is usual with battleships. This, by the way, is the weakest feature of the battleship, and with the present type it is most difficult, and one might almost say impossible, to fit decks strong enough to withstand plunging fire.
It does not need to be pointed out that at such ranges the side armor of either type of ship is practically a negligible quantity, since the width of the target, in the line of fire, is, in the case of the deck, several times as great as in the case of the side belt. Thus, with an angle of fall of 30°, the target offered by the deck is about 100 feet in range, while that due to a belt 8 feet above water is but 14 feet. This is with the ship broadside on, and with any other presentation the difference is greater.
It has often been claimed for the battle cruiser that on account of her speed she can choose her range. That is quite true, but it is of advantage to her, leaving out of consideration a fight with an inferior ship, only to obtain and retain long range, and this seems to have been what was really meant, since the effort was made to give her guns supposedly able to outrange those of her possible opponents. It might here be stated that such outranging is not possible, except as we compare her with older ships, since, aside from the fact that in a contemporary design similar guns might be used, there is, in guns of about the same size, no great difference between their possible ranges at any given elevation, and there need be no limit to the elevation up to the point of maximum possible range, which is much beyond present necessities.
The speed of the battle cruiser, then, in a ship to ship action, is of advantage to her only to avoid close action, which must usually be disastrous to her, and to place her, as far as her protection is concerned, on a par with the battleship. It does not, however, overcome the handicap of smaller battery, so that, other things being equal, a ship to ship action between a battle cruiser and a battleship, both of the present type, must of necessity end in disadvantage to the former. Of course, speed gives the advantage of possible combination of forces against detached enemy units, but this would probably be against an already beaten enemy.
Long range, therefore, offers the only means by which the lightly armored battle cruiser can hope, in action, to give as much as she must take. It will then be in order to investigate the prospects such a vessel would have in such an engagement.
Although assuming equal skill on both sides, long range firing really requires less skill, except in spotting, than in the case of short ranges. This is because the error in range due to a given error in elevation is much less at longer ranges, so much so that at extreme ranges, with high elevations, there might be several degrees error in elevation with no great error in range. It all comes down to a matter of skill in spotting and keeping the range. With equal skill, hitting at long range is entirely a question of chances, and is practically in accordance with the law of probability.
This being so, the question is at once seen to be one of the number of shots that can be fired on either side, in equal times. This also, since equal rates of fire per gun must be assumed, is reduced at once to the simple matter of the number of guns on the two sides, so that, where the battle cruiser has eight guns to the battleship's 12, it is readily seen that it will require at least three of the former to be on even terms with two of the latter, neglecting any superiority in fire control that is inherent in the superior fire concentration of the two battleships. Since battle cruisers cost twice as much as battleships, and require the same numbers of men per ship, it can hardly be said that building battle cruisers to fight battleships is an economical proposition.
Since the battle cruiser must fight a capital ship at long range, and since, at such ranges, vertical armor becomes so small a target as to have a very small chance of being hit, the idea seems to suggest itself to save money and displacement by omitting such side and other vertical armor, and indeed this seems quite logical. In action with a battleship at any range, it would seem that such armor as can be carried would probably be penetrated if hit, and the only reason that might be assigned for carrying it at all is to prevent damage from the lighter guns of small craft, if the vessel were unexpectedly to find herself in close contact with such small craft.
This could not be called a logical reason, as the weight of armor to be carried would be a severe penalty to pay for the chance of accidentally or carelessly running into such an encounter. In any case, if the turrets and conning-tower were lightly armored, there could hardly be much damage done in the few minutes necessary for the larger vessel to wake up, and careful hull design could keep it at a minimum. Besides, the same reasoning that requires the armor would make necessary elaborate underwater protection against torpedoes, since there is a pretty fair chance of being in range of a torpedo vessel. This is not done, cannot be done, for obvious reasons, and is very frankly left to chance. It seems clear that most of the armor should be omitted.
The same reasoning that requires the omission of the armor will also indicate the uselessness of armored decks. The vessel cannot fight at short range, at which only the armored deck would be of value. At long range any deck that could be fitted would be penetrated. It seems clear that the heavy weight of decks that are fitted for protective purposes only should be saved.
These two changes would at once make an enormous reduction in the displacement and cost of the vessel, other things being equal. It would appear feasible to reduce the displacement 7000 to 8000 tons without affecting the other characteristics, or to, say, 27,000 or 28,000 tons. Even this might be a high figure, since considerable power will also be saved, for the same speed.
Omitting the protection will reduce the cost of the vessel so much that more ships can be placed in the line to fight against capital ships. This consideration in itself will reduce the handicap under which the vessels must work, although the battery power of the individual vessel is not increased.
The vessels now carry a heavy weight of battery, although the number of guns is small. Consideration of the law of probability, as has been indicated above, shows that the vessels should instead carry a large number of guns, if they are to fight battleships on equal terms. It is clear that they cannot carry a larger number of the same heavy guns without again increasing size and cost. There is then no course open, if the number of guns is to be increased, except to use a smaller and lighter gun. It is then necessary to decide as to the proper caliber and weight of gun such a vessel should carry.
As the greatest possible number of guns is to be mounted, the smallest and lightest gun possible must be adopted. This will be the smallest gun that can be relied upon, at the fighting range selected, to carry its projectile through the armored deck. On the same weight of battery, and assuming that our present design carries eight 50-caliber 16-inch guns, these could be replaced by twelve 14-inch or by nineteen 12-inch guns of the same type. The number of hits at long range, in a given time, with the 12-inch battery, would be nearly two and a half times as great as would be obtained with the 16-inch battery.
Now, a complete penetration through the protective deck by any large projectile, such as has been considered, should nearly always result in an explosion in a machinery space or magazine, or similar vital space, and every such hit would most likely be a serious matter, whether the projectile were 12- or 16-inch. It would be difficult to show that the larger projectile could produce more serious effects, since in either case the immediate space reached would be placed out of action, and the effects would not be likely to extend much beyond that space. To get effect from a hit, there is, therefore, nothing material to choose between these calibers.
It seems then that the 12-inch battery will give two and a half dangerous hits from one ship, where we obtain only one with the 16-inch battery. There is, under the circumstances, no choice except to adopt the smaller caliber. Incidentally, although this is never a controlling factor, the smaller caliber should be a better weapon against an inferior ship, or against one of her own class.
If the same reasoning is carried farther, it would seem that a 10-inch gun would be even better. There is, however, the question of penetrating power to be considered, and at the necessary fighting range the small caliber would not be likely to give sufficient penetration. We therefore conclude that nothing smaller than the 12-inch gun would be advantageous.
We have now arrived at a type of 'ship which has the high speed of a cruiser, by means of which she can select and keep a long range, at which she is, from the point of view of protection, on even terms with the battleship, and which also has a battery capable of giving 19 dangerous hits in the same time in which the standard battleship can give but 12. This is, of course, on the assumption that the range is not so great as to prevent a sufficient number of hits before her allowance is exhausted. If our reasoning is correct, we have now designed a ship that under the given conditions must be superior to the battleship.
The resulting vessel is, however, still very large and correspondingly costly, and we could not afford to build in great numbers, such as are desirable, seeing that the vessel is needed as a scout and must replace the present scouts as well as the battle cruisers. If the displacement could be cut down to 20,000 tons, the vessel would be much more serviceable as a scout, and, provided the number of guns were not seriously reduced, would still be an ugly customer for a battleship to fight at long range, especially considering the larger number of ships that could be provided at the reduced cost of the smaller units. This smaller size could be somewhat approached by reducing the speed, but this is a doubtful expedient, and the desired result can be better obtained by using a shorter gun.
We have assumed a gun of 50 calibers length, which will not have an angle of fall exceeding 30° except at a range of more than 25,000 yards, if the long-point projectile of standard weight is used. As the number of hits that could be made at such a long range is probably not great enough to produce results, it will be necessary to reduce the range to, say, 18,000 yards. A 12-inch projectile of 2000 foot-seconds initial velocity will have, at 18,000 yards range, an angle of fall of about 30°, and a remaining velocity of about 1200 foot-seconds, which is most likely sufficient to give penetration through a 3- to 4-inch deck. Such conditions can be obtained with a gun of but 35 calibers length, the weight of which would be but half that of the longer weapon. As the weight of the mountings would be correspondingly light, twice the number of guns could be mounted in the same ship, or, what is more to the point, the required number can be mounted in a smaller ship, of the limited size we have been considering as desirable. This is done without sacrificing the speed to any great extent, although to avoid abnormal power in the small ship, the speed should be cut to, say, 32 knots.
The following would then be the general dimensions and chief features of the suggested design:
Length, 650 feet.
Beam, 76 feet.
Draft, 28 feet.
Displacement, 20,000 tons.
Speed, 32 knots.
Power, 100,000 I. H. P.
Battery, sixteen 12-inch 35-caliber guns.
Four 4-gun turrets, with 2-inch sides, 3-inch fronts.
Conning-tower of 3-inch armor.
No other armor, no armored decks.
Ammunition, 300 rounds per gun.
Oil supply, normal, 2000 tons.
There would be no torpedo outfit and no secondary battery. These would appear to be out of place on a vessel of this character. The latter, for use against light craft, is replaced by the light 12-inch battery, and, if desired, there could be supplied for this purpose a thin-walled projectile of about half the standard weight.
Needless to say, a vessel of this kind requires good visibility to develop its full usefulness against capital ships, though it should be within the limits of possibility to develop means of controlling the fire, somewhat in the same way as fire control is practiced ashore. This could probably only be done to a limited extent and under favorable circumstances. Thus, for instance, the battleships being engaged at shorter range, they might have a special fire control party to spot for the cruisers. Many other methods, more or less undeveloped, might be suggested, but of course good visibility makes these vessels independent, which is a great advantage.
A partial range table for the gun described may be interesting:
It will be seen that the angle of elevation has great relative intervals, so that errors in pointing will have correspondingly small effect, and so will differences in jump, roll of the ship, and other causes of dispersion. As is well known, at long ranges the dispersion in range decreases, so that, given good fire control, the vessel ought to make good practice at these ranges. At any rate, even if no more than 1 per cent of this is attained, the result, before the allowance is exhausted, would be 48 hits with 12-inch shell, most of them striking on the armored deck of the enemy, under conditions that would make complete penetration of the deck and explosion within the vital spaces nearly certain.
It is not by any means intended to convey the idea that the cruiser described can take the place of the battleship, or that, if such vessels were built, the battleship would become unnecessary. The latter must always remain as the one vessel which, under any conditions of weather, can successfully stand up and fight any surface vessel of the enemy, provided only that she can come within range. The cruiser described, being an amalgamation of the scout cruiser and battle cruiser types, will do the necessary scouting and screen work of these types, and will finally, on the great day of battle, when all the forces possible must be made available, be ready to take her place in the line and fight the enemy battleships, after having, in all probability, been previously used to bring the enemy to action, by destroying his screen, his auxiliaries, in fact, by delaying the battleships themselves, on account of the tremendous fire they must receive without adequate return fire, until they turn to defend themselves. No success is however possible without the battleships, which alone can sustain action at close range and prevent the enemy from breaking through.
The battleship is the only vessel that can never be caught at a disadvantage, assuming equal numbers, as long as she can get within sufficiently close range. The cruiser, on the other hand, must not be caught at close quarters, and must choose her conditions. These circumstances might be construed into a great handicap for the cruiser, and indeed they are so; but is it not the province of strategy to overcome such difficulties, to choose conditions favorable to oneself, and, if possible at the same time, unfavorable to the enemy?
The numbers of these vessels that might be required would be determined on the basis of their use as scouts, and would be quite large. The use of these vessels against capital ships might even be considered incidental, yet we would have the satisfaction of knowing that, when action is joined, they would not be an encumbrance, they would not need protection, their crews would be fighting men instead of non-combatants, the money invested in them would not be an extra outlay for special purposes only, but would become actually available in action; in short, we would realize in one more type of vessel the kind of fleet efficiency and economy desired.