From that bit of naval history we can almost see for ourselves what the characteristics of the destroyers must be. They have to be bigger than the torpedo boats, but as the latter were quite small the destroyers, though larger, are still comparatively small craft, latterly of about one thousand tons. Then they have to be very fast, in order to be able to chase the others and, finally, they need one or two guns, comparatively small so as not to overburden the ship and yet large enough to dispose of anything of their own size or smaller.

Unquestionably, their greatest feature is their speed. They are the fastest ships afloat, rivalling even a fairly fast train. Some of them can exceed forty miles an hour. They are very active and nimble, too, being able to turn in a comparatively small circle. For warships, too, they are cheap, so that a commander can afford to risk losing a destroyer when he would fear to risk another vessel. For all purposes except the actual hard-hitting they are the most useful weapon which the commander of the fleet possesses.

When the main fleet puts to sea a whole cloud of these smaller craft hover round looking for submarines or for the surface torpedo boats which might try to attack the large ships under cover of darkness, while keeping a sharp look-out, too, for mines or any other kind of floating danger, and thus they screen the more valuable ships.

Likewise do they convoy merchant ships sometimes, especially through waters believed to be infested with submarines. They also sally forth on little expeditions of their own, knowing that they can fight any craft equally speedy and show a clean pair of heels to any heavier ships, while by adroit use of their own torpedoes they may even "bag" a cruiser or two.

They are pre-eminently the enemy of the submarine, for the under-water boat is necessarily less active even when it is on the surface than they are, so that a submarine caught by a destroyer stands a very good chance of being rammed by it, which means that the destroyer deliberately rushes at it, using its own bow as a ram wherewith to knock a hole in it. Or if that be not practicable the destroyer, while dodging the torpedo of the submarine, may plant a single well-aimed shot into its opponent and the fight is over. A cleverly-handled destroyer appears to have little difficulty in avoiding the comparatively slow torpedo, but no ship ever built could avoid a properly aimed sh.e.l.l, two facts which are clearly indicated by the very few cases in which, during the war, a destroyer has succ.u.mbed to a submarine. The gun of the latter, if it has one, is no match for the guns of the destroyer.

Naval strategy and tactics, when one thinks about them carefully, reveal a very close resemblance to those of the football field. The destroyers are like the forwards, quick, light and nimble, valuable chiefly because of their ability to run swiftly and to dodge cleverly, while the heavy, stolid backs represent the battleships in their ability to withstand the heavy shocks of the game. Any imaginative boy will be able to carry this simile farther still and a comparison of the description of the battle of Jutland with his own knowledge of the game will reveal a surprising parallelism.

Thus the reader will to a very large extent be able to see for himself the manifold uses to which these wonderful little ships lend themselves, and he will see that above everything else it is their speed which counts, which fact gives us the key to their peculiar construction.

To commence with, they are made as light as possible. The material used is different from that of ordinary ships, being "high-tensile" steel, a steel into which a little more carbon than usual is introduced, resulting in about 50 per cent higher tensile strength but also involving, alas! rather more brittleness. When made of this material the whole framework of the vessel can be made of lighter beams and the covering can be of thinner plates than would be the case if the mild steel ordinarily employed for shipbuilding were used. The high-tensile steel is lighter for a given strength and therefore a ship built of it is lighter than it would otherwise have to be.

Besides the use of this particular material every resource in the way of ingenuity and skill on the part of the designers is bent towards saving weight. No unnecessary part is ever put in, but, on the other hand, necessaries are skinned down to the utmost limit consistent with safety in order to produce a light ship. How difficult this problem is is hardly realized until one thinks of the conditions which prevail when a ship floats in the water. The upward support of the water is exerted in a fairly regular way all along the ship while the weights inside which are pressing downward are concentrated in lumps. The engines, for example, represent a very heavy weight concentrated in one fairly confined spot. Thus the vessel has to have sufficient stiffness to resist the action of these opposing forces which are thus tending to break her in two. That, moreover, occurs in the stillest water; when the sea is rough still worse stresses are brought to bear upon the comparatively fragile hull, for a wave may lift each end, leaving the middle more or less unsupported, or one may lift the middle while the ends to a certain extent are left overhanging. All this, too, is in addition to the knocks and buffets caused by huge volumes of water being flung against the ship by cross seas in the height of a tempest. In the case of ordinary ships where speed is not of such great importance, the problem is simplified by the use of what is termed a high "factor of safety," which means that the designers calculate these forces as nearly as they can and then make the structure _amply_ strong enough. In other words, care is taken to keep well on the safe side. In a destroyer, however, there is no room for such a margin of safety. Risks have to be taken, and it is only the high degree of skill and experience possessed by our ship designers which enable these light ships to be made with, as experience shows, a very considerable degree of safety. They have to be continually choosing between strength on the one hand and lightness on the other and the way in which they combine the two is marvellous.

The weight thus saved is used for carrying engines, boilers and fuel.

Relatively to its size, the destroyer is about as strong as an egg-sh.e.l.l, but its engines are of extraordinary power.

The destroyers are generally organized and operate in little groups or flotillas of perhaps twenty or so with a small cruiser or a flotilla leader as a flagship, on which is the officer in command of them all.

There is also usually a depot ship for each flotilla.

The flotilla leaders are what one might call super-destroyers, about double the size of the ordinary large destroyer, which is to say, about two thousand tons, and capable of very high speed.

The depot ships form a kind of floating headquarters for their respective flotillas. They are usually old cruisers which are specially fitted up for the purpose, and although they are of comparatively slow speed they can by wireless telegraphy keep in touch with the destroyers, which can return to them when occasion permits or demands. They carry workshops in which small repairs can be carried out, spare ammunition and stores of all kinds and spare men for the crews. In fact they can look after the smaller craft much as a mother looks after her children, and for that reason they are sometimes called "mother ships."

As has been said, the destroyer was originally intended to destroy torpedo boats, but small torpedo boats have almost gone out of existence or rather the cla.s.s have so grown in size as to have become merged in the destroyers, which, it must be remembered, are well armed with torpedoes which they have at times used with great effect. It is not surprising, therefore, to find that a still newer cla.s.s of ship has arisen which has been described by one authority as "destroyer-destroyers." Officially known as "light armoured cruisers," not very much is known of their details. They are, however, about 3500 tons, with 10 guns, large enough that is to dispose of any destroyer which they might encounter.

Thus, to review the whole cla.s.s of ships of which we have been speaking, we may say that there are the destroyers, all the more recent of which are about 1000 tons but diminishing as we go backward in time to about 350 or 400; the flotilla leaders about twice the size of the largest destroyers; and the destroyer-destroyers nearly twice as large as the flotilla leaders: all are characterised by high speed and by guns just large enough for the work for which they are intended. All are armed, too, with the deadly torpedo for attack upon larger ships than themselves.

They are essentially night-birds, much of their time being spent stealing about with all lights out, in pitch darkness, seeking for information or for a chance to put a torpedo into some chance victim.

These night operations are very hazardous, but so skilful are the young officers who have charge of these boats that seldom do we hear of mishaps.

But although, as has been said, the torpedo boat has almost vanished, its under-water comrade has recently a.s.sumed a place in the first rank of importance, and perhaps to us the most valuable work of all done by the destroyer is that of hunting down and sinking these modern pirates.

CHAPTER XVI

BATTLESHIPS

Perhaps the greatest war invention of modern times was the British battleship _Dreadnought_.

Of course, there have been battleships for centuries. In history we read of fleets consisting of so many "ships of the line" or in other words "line-of-battle" ships, meaning ships which were considered capable of taking their place in "line of battle," as distinguished from "frigates"

which correspond to the modern "cruiser."

The "line-of-battle" ships were stout and strong with plenty of guns.

They went into the thick of the fight, since they were capable of giving and receiving hard blows, while the lighter frigates hovered around seeking an opening to use their higher speed to cut off stragglers or to prey upon merchant ships.

Although so different in form and material that a sailor of the old days, could he revisit the earth, would not recognize them, the battleships of to-day are the real descendants of the "line-of-battle"

ships of those times. They are stout and strong, with the heaviest guns, capable of giving and taking the hardest knocks, and it is they who form the backbone of the fleet. As we saw in the accounts of the battle of Jutland, the German Fleet tackled our cruisers and lighter vessels but discreetly withdrew when the battleships came up.

Looked at in another way, we may say that a battleship is a floating fortress. Its speed is not great, when compared with other ships, but it is constructed to carry enormous guns. It is also armoured with steel plates of great thickness and of special hardness placed upon the outside of the hull so as to cover its vital parts and protect them from the sh.e.l.ls of the enemy. Its chief function, we may say, is to carry its guns: to enable it to do this with safety, it is armoured: and to enable it to get to grips with its enemies it has engines and boilers. Those are the three features of greatest importance in a battleship, its guns, its armour and its engines. All else is of minor importance.

It is strange to think how short a time the iron or steel ship has been with us. In the American Civil War, for instance, only about sixty years ago, the battleships were made of wood. It was during that war that Ericcson thought of the idea of putting iron plates to protect the sides of a ship from the hostile shots, and from that improvised armouring of a wooden ship has arisen the iron-clad or, more correctly, steel-clad monsters of to-day.

It is just about fifty years ago since the last iron-clad wooden battleship was launched for the British Navy. Her name was _Repulse_, and she took the water in 1868. With a tonnage of 6190 and a horse-power of 3350, she had a speed of 12 knots. Her armouring of iron was in parts 4 inches and in other parts 6 inches thick, while she carried 20 guns of sizes which to-day would seem mere toys. If all her guns were discharged together she would throw a total weight of 2160 lbs. of projectiles.

Now, for comparison, let us take a modern battleship, the _Orion_, for example. The tonnage is 22,680, the horse-power 27,000.

She is more than twice the length of the older ship and is armoured with steel 12 inches thick. Her 10 large guns, each 13 inches in diameter, if fired together (as I once heard them, like thunder, though 10 miles away) throw a weight of 12,500 lbs.

From this we see the wonderful growth in size, speed and in hitting power during the comparatively short period of fifty years. But there is a more striking comparison still.

The _Repulse's_ guns threw 2160 lbs. and the _Orion's_ throw 12,500. But that takes no account of the energy with which the weight is thrown. A tennis ball hit hard, might really contain more energy and do more damage to anything it hit than a cricket ball thrown gently, which ill.u.s.trates the fact that in comparing the power of guns we need to consider something more than the mere weight of the projectiles. To arrive at a real comparison we take the weight of the projectiles in tons and multiply it by the speed at which they leave the guns in _feet per second_. And we call the answer so many "foot-tons."

Now the energy of the _Repulse_ thus reckoned comes to just under 30,000; that of the _Orion_ to just under 690,000. The _Orion_ can hit twenty-three times as hard as could its forerunner of only fifty years ago.

Since the _Repulse_ all our battleships have been built of wrought iron or mild steel. Speaking generally, there was a steady development in size and horse-power and in speed until 1906, in which year there was launched the world-famous H.M.S. _Dreadnought_. Previously no battleship had been faster than 19 knots: she was designed for 21 knots. Her tonnage was 17,900, exceeding by more than 1000 tons anything that had gone before. But the great change was in the guns. Pre-Dreadnoughts had, or one ought to say "have" for there are still many in existence, four of the biggest guns, a number of medium-sized guns and a still larger number of smallish guns intended for the purpose of keeping off torpedo craft and such small fry.

At one stroke Lord Fisher, who was then the First Sea Lord of the British Admiralty, changed all this. He swept all the medium-sized guns away and gave this new ship TEN of the largest guns then in use.

The advent of this ship startled the whole naval world, for it was seen at once by all those able to judge that there was a vessel which might be expected to sink with ease any other ship afloat. The onslaught from those ten guns would be more than any other ship could stand. So other powers set to work to copy more or less exactly, while Great Britain quickly built more like her. So important was this new invention that very soon the strength of the naval powers began to be reckoned entirely on the number of Dreadnoughts they possessed, the older ships being left out of account as though they did not make any difference one way or the other.

But Great Britain was not content with the _Dreadnought_, for each succeeding ship or set of ships was improved until, only four years later, there was launched the _Orion_ already referred to, nearly 5000 tons bigger, with 2500 more horse-power, and with 13-inch guns instead of 12-inch. The _Orion_ and her sisters are often spoken of as super-Dreadnoughts.

The Dreadnoughts as a cla.s.s are often referred to as "all-big-gun"

ships, since that is the feature which most distinguishes them from those which went before.

These large guns are mounted in turrets as they are called. We might describe these as turn-tables with a cover over something like a small gas-holder. There are usually two guns in each turret, although there are a few ships whose turrets have three in each.

The turrets seem to be standing on the deck of the ship and it is by turning them round that the guns are trained or pointed at their target.

The original _Dreadnought_ had one turret in front and two behind, all on the centre-line of the ship, and two more, one each side, amidships.

In late vessels all five turrets are on the centre-line. Thus the _Dreadnought_ can fire six guns ahead, eight astern and eight to either side, while the newer ships can fire four ahead, four astern and all ten on either side.

There are other battleships with even more guns than these, such as the U.S.A. ship _Wyoming_, with twelve 12-inch guns, but the British Navy seems to prefer to stick to the original number of ten. The reason for this is that every such ship is a compromise between three alternatives.

The three great features have already been pointed out, namely, the guns, the armour and the propelling machinery. Either of these can be increased at the cost of one or both of the others, but all cannot be increased without sinking the ship, unless indeed, the ship be made larger and then other considerations crop up.

And that brings us to another cla.s.s of ship often ranked among the battleships. These remarkable vessels are also termed cruisers and the fashion seems to have established itself of combining the two names and calling them battle-cruisers. They gave a fine account of themselves during the war.

The first three of these, of which the _Invincible_ is usually taken as the type, made its appearance the year after the _Dreadnought_, and like the latter were the offspring of the fertile brain of Lord Fisher. The _Invincible_ was about the same size as the _Dreadnought_, but had nearly twice the horse-power (41,000), which enabled it to attain an actual speed of nearly six knots more, namely, 286.

For guns it had eight of the same large weapons, and it was armoured with 7-inch steel armour-plates instead of 11-inch.