The submarine boat is the guerilla in warfare. Its tactics are the tactics of the Indian who fights under cover or lies in ambush for his enemy. These are necessarily the tactics of all weaker individuals and are an essential method of procedure in preventing the weaker party from being annihilated by the strong and more powerful. Some people have contended that the submarine is an unfair weapon, but the old statement that "all's fair in love and war" applies to the submarine as it does to every weapon which has been invented since the days when men struggled for supremacy with their bare hands. The first man who wielded the club might have been accused of being unfair; the same term might have been applied to the man who invented the sling-shot or the bow and arrow. When people fight for their existence, the existence of their families or of their country, they do not fight according to the "Marquis of Queensberry Rules." A revolver in the hands of a weak man or a defenceless woman is a proper weapon to enable them to protect their property, their honor, or their life; and, no matter what theorists may claim, the submarine will remain as a weapon to be reckoned with in all future wars, provided there are future wars upon the high seas. In making this assertion I do not intend to justify a great many of the acts performed by the submarines of one of the belligerents in the present war. I do claim, however, that the submarine is a perfectly legitimate naval weapon, and that it deserves a place in the armament of any nation whose military power is maintained for purposes of self-defence.
Above all, I believe the submarine most fitted to act as a weapon in coast-defence operations. Coast-defence submarines will probably be found to be the most important adjunct to the navies of every country whose policy is to defend their own coast lines, rather than to attempt aggressive warfare. Vessels for this purpose do not need to be of great tonnage nor of high speed. Speed is the one thing, more than anything else, which runs up the cost of the submarine vessel. While speed is desirable for the cruising submarine, it is not an essential for a defensive submarine. It is possible to get a speed of fourteen or fifteen knots in a submarine of about five hundred tons displacement, and at the same time have comfortable living quarters for the crew. A boat of this size may carry eight Whitehead torpedoes, each torpedo being capable of destroying a fifteen-million-dollar battleship, and as a five-hundred-ton displacement submarine can be built for about one-half million dollars, and is capable of carrying eight Whitehead torpedoes, potentially good for eight fifteen-million-dollar battleships, or a total of one hundred and twenty million dollars' worth of capital ships, it seems as if that would be sufficient to ask of one little submarine boat. Now to double that speed would require a much larger vessel, and would cost approximately two and one-half million dollars. A two and one-half-million-dollar boat for the defence of harbor entrances or seacoast cities would not carry as many torpedoes as five of the five-hundred-ton boats. A torpedo fired from a small boat is fully as potent as one fired from a two and one-half-million-dollar boat.
These small boats could be located at five different points covering a portion of our coast, and the chances are that at least two of these smaller boats could reach an objective point on the coast line under their protection in shorter time than one large high-speed boat would be able to do. At the same cost they could cover the same area of coast line to a much better advantage, as there would be five of them to protect that area instead of one.
We will assume, for purposes of illustration, that the Sandy Hook entrance to New York Harbor is to be defended. If we strike a fifteen-mile radius from Sandy Hook point, running from the Long Island to the New Jersey shore, and have four submarines take station on that radius line about five miles apart, no ship could pass that radius line without coming within the range of vision of the commander of the submarine, either from his periscope in daylight or at night within the range of hearing of his "submarine ears." The Fessenden oscillators, or microphones, now installed in all submarines, would readily detect the approach of a surface ship or ships. These instruments have been improved to such an extent that it is now possible to carry on wireless conversation under water between one submarine and another for a considerable distance. Communication by the Morse code, or other special codes, may be carried on between submarines up to a distance of several miles.
It would be possible for groups of submarines on station, or picket duty, so to speak, to be in constant communication with shore stations, either by submerged telephone stations or by wireless. In that way the submarines can be kept in constant touch with the country's scouting fleet of high-speed surface vessels or aeroplanes and immediately be notified of the approach of an enemy's fleet or ship. There is no way in which they can themselves be detected, so far as I am aware, as there is no need to run the machinery of the submarine while lying at rest on picket duty, and it would be impossible for a surface ship or flying machine to detect them, providing a constant watch was kept on the horizon or the heavens through the aeroscopes.
As the effective range of the modern Whitehead torpedo is about three miles, no ship could pass between the submarines without passing within torpedo range. However, a commander of a submarine would hardly take a chance of making a hit at such great distance, and on sighting the enemy he would leave his station and attempt to intercept her, so as to get a shot at shorter range. If the enemy succeeded in running the gauntlet of the outer circle it would have to pass the submarines distributed on, say, a ten-mile radius. Three submarines would be able to protect this radius line. A five-mile radius might also be established with two submarines, and one located at the entrance. To enter Sandy Hook, therefore, a ship would have to run the gauntlet of five or six submarines without it being necessary for them to leave their stations.
Submarines with high speed will become valuable as commerce destroyers and for carrying on an offensive warfare. [Page 32] shows a high speed, sea-keeping, fleet submarine of the "Lake" type. Its principal characteristics are the same as those of the coast-defence type, except that the buoyant superstructure is increased in height sufficiently to form living quarters for the crew when cruising in surface condition.
One of the essentials of a high-speed sea-going vessel is high-powered machinery. A large portion of the interior of the pressure-resisting hull, therefore, must be devoted to machinery space. The quarters would necessarily be somewhat cramped without a buoyant superstructure, which gives plenty of room for the crew to take exercise and secure plenty of fresh air when off duty, even in rough water. As it is very important to keep the physical and mental condition of the crew in a satisfactory state, it is essential that the men be not kept in restricted quarters for a long period of time.