When the naval powers were waking up to the fact that the submarine was worthy of some consideration, undersea tactics was a thing that was yet to be invented.

These early craft had a very short range of travel and because of their poor construction and lack of power they were not at all adapted for ocean-going, hence they could not accompany the fleet of warships on their maneuvers.

They were, however, thought very well of for coast patrols, and this was the duty given them to perform; each submarine had a stretch of coast which it was to watch and tactics and maneuvering were not needed for this service. Even when it was expected an attack might be made, the only thing that was required of them was to be on the lookout, signal the forts on shore, dive and get out of harm’s way.

But as the size, range, and speed of the submarine was increased she gradually took her place along with the auxiliary[32] craft of the fleet, or squadron,[33] and began to take part in the maneuvers with it. It was then that certain fixed duties were assigned to her, and her relation to the other boats became more clearly defined and definitely fixed.

As late as the Spanish-American War, and that was only a score of years ago, the submarine played but a sorry part. A few years later, however, when the Russo-Japanese War was fought, the underwater fighting craft showed for the first time in the game of naval warfare the kind of stuff it was made of.

In the years of peace and prosperity that passed between the end of the Russo-Japanese War and the beginning of the great world war of the nations that is now going on, the submarine was experimented with and improved upon until it has thrown all the other types of naval craft, from the dreadnaughts on down into the shade where there isn’t any shade.

The result of it all is, as you probably know, that the submarine has developed a kind of warfare all its own and which it carries on entirely without help. Imagine, if you can, that in the greatest war that has ever been waged giant battleships are sewed up in the harbors of the enemy while her submarine flotillas are everywhere at sea and carrying on a most effective blockade! Such is the rise of the submarine.

The Uses of the Submarine.—There are two chief uses to which the submarine is put, and these are (1) as a reserve defense or offense for the fleet, and (2) as an offensive weapon for the purpose of maintaining a blockade.

How She Works with the Fleet.—In the first instance, that is, where the submarine is used as a means of defense and of offense with a fleet or squadron, her tactics are well defined and clear-cut.

Her activities under these conditions are rather limited, for she is not built speedy enough to keep up with a swiftly steaming fleet. This, then, in the very nature of things, keeps the submarine from playing an otherwise all-important rÔle of scout-ship.

Further, this lack of speed on her part prevents her from engaging in battle as an actual part of the fleet or squadron, for very often it is the speed of the attacking men-of-war that makes for victory, and a flotilla of submarines that lagged behind would prove more of a hindrance than an aid.

But what the submarine can and does do to great advantage is to attack an enemy fleet either as a defensive or an offensive measure, depending on the relative strengths of the fleets which oppose each other.

The Submarine Flotilla as a Means of Defense.—Now let us see first what happens when a fleet with a flotilla of submarines attacks another fleet which is without them.

If the attacking fleet is the weakest—that is, its guns are the lightest—then the submarine flotilla will take a defensive stand, though the opposing fleet is making the attack. The submarines will lay off to the rear of the attacking fleet, and then if the gun-fire from the enemy waxes so warm that the attacking fleet is forced to retire the submarines are in a good position to aid the fleet in its retreat, as shown in Fig. 61.

Now, as soon as the pursuing ships come within range, the submarines let go their torpedoes at them and these either blow them up, cripple them, or scare them off. In a maneuver of this kind the commander of the fleet executes his retreat in such a way that the heavier-armed pursuing fleet must pass near his submarines, which are usually submerged and are therefore invisible.

The Submarine Flotilla as a Means of Offense.—If, now, the attacking fleet is stronger than the defensive fleet, then the submarines of the attacking fleet will also take an offensive part. In this case the submarines will take up a position to the rear of the defensive fleet.

The commander of the attacking fleet will then use such force on the enemy fleet that it will retreat along the path where the submarines lay, when they will, of course, torpedo them, as shown in Fig. 62.

Both these methods of attack have been used with signal success in the war that is now going on.

The Submarine as a Scout.—Although the submarine is useless as a scout for a swiftly moving fleet still it can render great service as a scout on its own hook.

By way of illustration let us suppose that the enemy has a harbor that is well protected by forts and guns, that her fleet is laying to in it, that we want to know how many ships the fleet is made up of, and, finally, what class of ships they belong to.

It is the duty then of a submarine to get into the harbor and take a general survey of the situation. You may wonder how the craft is to do this, since the harbor is mined; but by skilful handling, the captain will usually get through safely, find out all that he wants to know and run out again.

Besides thoroughly reconnoitering a harbor, the submarine can lay a few contact mines, as we explained in a chapter that has gone before, in positions of which the enemy fleet is in entire ignorance and which will be more than likely to result in the destruction of at least a part of the fleet.

Further, the submarine is used to destroy fields of mines which have been laid by the enemy in a harbor. This is done by mines thrown from the torpedo tubes among those that have been planted and which explode by the concussion.

The Submarine as a Blockader.—The most important use to which the submarine has ever been put and one that was never thought of seriously until the present conflict is that of a blockader.

Ever since the beginning of this war Germany has realized the tremendous need of keeping the neutral[34] countries from supplying the Allies with munitions and food supplies, and she has prepared for years a blockade of a new and very effective kind, and this is by destroying merchantmen by submarines.

England and the other Allies have done the same thing with the Central Powers—which is not a very hard thing to do because Germany’s fleet of warships is cooped up in her various ports and dare not venture forth, and so the task is left entirely to her submarine flotilla.

And what makes it still harder for the German submarines is that the Allies keep on the constant watch for these enemy undersea craft, and this they do with their submarine destroyers, and the United States is after them with her submarine chasers, to say nothing of England’s aircraft attacks.

Altogether it is very hard for the enemy submarines to keep in touch with their respective bases or to receive orders as to their courses of action. When on blockade duty, then, the captain of a submarine is in very truth, the commander of his craft and it is strictly up to him to determine what her tactics shall be.

As long as he does his work well, which means that he sinks a fair number of all the ships that enter his zone, his superior officer, wherever he is, will have no quarrel with him as to when or how he does the work.

So you see the tactics used by the captain of a submarine while doing this kind of work depend entirely on the conditions he encounters at the moment, and on the quick decision and judgment of the captain depends the success or failure of the attack.

How a Submarine Attacks a Merchantman.—As a general thing submarines travel alone when merchantmen are to be torpedoed.

The sea is mapped out into zones, as certain areas or parts of the sea are called, and each zone, or part, is usually assigned to a single craft; the submarine patrols this zone constantly, and the captain and his officers keep their weather eye open for passing merchantmen or vessels which might in any way aid or carry supplies to the enemy.

To do this the captain of the submarine stops every ship that comes his way and has her papers and cargo examined, and in this way finds out whether the ship is what she seems to be or if she carries contraband—that is arms, ammunition, and war supplies of any kind—or not.

The way in which this interesting procedure is done is as follows:

The submarine, let us say, has sighted a ship, and seeing that it is to all intents an unarmed merchantman she rises to the surface and trains her rapid-fire guns on the craft. Next she signals the ship to stand by and at the same time she runs toward her.

Now the captain of the ship has three courses open to him: (1) to put on full speed and try to get away, trusting to luck to prevent his craft from being shot full of holes or torpedoed; (2) to take a still greater chance and try to ram the submarine with the sharp, steel-shod bow of his ship and so either disable or sink her, and (3) to comply gracefully to the request and heave to.

If the latter is done, the collapsible boat of the submarine is rigged up and a couple of the officers and crew row over to the ship, when they are hauled aboard and go through her. Should they find nothing of a suspicious or contraband nature, the boat returns to the submarine and the ship is allowed to go her way.

But, on the other hand, if contraband is found on board, the captain of the submarine will do one of these two things: (1) he will warn the crew of the enemy ship that he is either going to open fire on her with his guns or torpedo her, and to take to the life-boats, or (2) he will sink her without warning if the whim so seizes him. Often the captain of the destroyed craft is taken aboard the submarine and held as a hostage.

When Submarines Attack in Pairs.—Another strategic scheme that is used to torpedo enemy craft is to work submarines in pairs.

This is not done, as a rule, except where the ships may, in virtue of their armament, prove dangerous to a single submarine and then they are sunk without warning.

Tactics of two different kinds are used in the actual stopping of the craft. The first is for the submarines to lay off from each other at a distance of from three to five miles (as shown at A in Fig. 63). Then when the submarine, with her periscope above water, spots an enemy ship, she signals to the other submarine, which is submerged, and gives her the exact speed and course of the armed vessel.

The submarine with her periscope above water cannot be seen by the ship because she is too far off, and the nearby submarine cannot be seen because she is totally submerged; so the first submarine directs the second submarine how to train her torpedo tubes on the enemy ship and when to shoot the torpedoes at her. By these tactics a ship can be sunk without either of the submarines being seen.

The other and second way by which an armed ship can be attacked is by having a pair of submarines travel together, one directly over and separated from the other by a distance of only twenty or thirty feet (as shown in Fig. 63).

Now, when a ship is sighted by the craft nearest the surface she comes up boldly and demands the hostile vessel to heave to. Should, instead, the enemy ship open fire and cripple or destroy the submarine, the submerged submarine takes up the fight and shoots a couple of torpedoes at the aggressive ship and so puts an end to her, if possible.

The tactics we have told you about are only a couple of the many used by present-day submarines; we should like to go on and write a book about them but if we did we’re afraid the Imperial German Government might not like it, so we’ll stop here.

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