The Future Of The Submarine

By Franklin D. Roosevelt
Assistant Secretary of the Navy

[The North American Review, October 1915]

Very long ago man discovered that he could kill whales because he had learned by observation that these biggest of animals had to come to the surface of the ocean at frequent intervals to breathe. Knowledge of their habits has been followed by their partial extermination. Because there have been of late so many wild conceptions of the habits of the mechanical whale, the submarine, a brief description of submarines in general is perhaps necessary to a clearer understanding.

Primarily, in spite of its name, a submarine is a surface vessel, with an underwater body similar to that of other surface vessels, and propelled by twin screws. The power to drive it on the surface is developed by so-called Diesel heavy-oil engines, or, as in some types, by steam turbines driven by oil-burning boilers. The requisite of these engines is that they may be shut off at a moment's notice, and thereafter create no heat or gases when submergence takes place. Great difficulties have been experienced with these engines in the past. The amount of space available, the mechanical problems of developing increased horsepower, have made progress seemingly slow, but within ten years the submarine's surface engine has gradually grown from the size for a 250-ton craft to that for the 1,000-ton so-called sea-going type, and the speed has been increased from 12 to 22 knots an hour. At the same time a 3 or 4-inch gun has been added to the equipment. Thus the result in the larger modern types is a vessel of about 1,000 tons, with fair speed, light armament and no armor, with sea-going qualities inferior to those of a destroyer, and with a cruising radius at reduced speed of 3,000 to 4,000 miles, though longer distances could possibly be covered by using the diving tanks for additional oil storage, thereby preventing diving operations. As a surface warship there is little to commend in these qualities: speed, protection and offensive power are all defective, and such a ship would be at the mercy of any other surface vessel stronger than a torpedo boat.

It is, however, as an underwater craft that the submarine gains in effective fighting strength, and incidentally in that appeal to the popular imagination which, sad to say, totally lacks war value. The moment the surface engines are shut off, and sufficient water admitted to submerge, the character alters; propelling power must of necessity become non-gas producing, electric engines run by storage batteries. They are entirely separate from the oil engines and can give but slow speed—10 to 14 miles an hour—for a few hours only before it becomes necessary to rise and run on the surface in order to recharge the batteries by means of the surface engines. But the need of coming up like the whale for breath is not the only weakness: to deliver an attack sight is an essential, and thus far man has discovered no means of seeing through the water. Invisibility is the source of a submarine's strength, and yet the only way an enemy can be seen in order to discharge a torpedo is by raising the "eyes" or periscope above the surface. The enemy becomes visible, but in the same act the submarine loses its invisibility, for a periscope can be seen if the proper means of observation are maintained. As an underwater craft, then, the submarine can hide when completely submerged, in which event it cannot see and has no offensive power; it can run submerged with periscope showing, in which case it can use the torpedo if not sooner discovered; it can operate at slow speed and for a few hours only without rising.

During the past century great changes have occurred in armed ships, but they have occurred gradually. People thought in 1815 that the steam frigate Demologos or Fulton the First would "revolutionize" naval warfare, but nations were still building sailing frigates thirty years later. The unseaworthy Monitor was supposed to upset all traditions, yet she was not the first ship to carry armor, and development in naval architecture was eventually along the line of ships with sea-going qualities. The torpedo boat of twenty years ago, with its great speed and self-propelling torpedo was going to put every battleship on the scrap heap, but very soon the destroyer was devised as an answer, and to-day has replaced the torpedo boat and taken its definite place as an integral part of the fleet. The more I study present-day naval development in the light of naval history, the more I am impressed with the slowness of evolution, with the fact that for every new weapon an antidote is found, and above all with the lesson that control of the seas means in its large sense precisely the same to-day as it did in the days of Van Tromp or Nelson. To prevent an invasion at one given point, to conduct a raid, to destroy isolated merchant vessels has never meant naval supremacy; but to be able to keep the seven seas open for the bulk of a nation's vessels of commerce and of war, and to keep the seas closed for those of the adversary—that is what history means by the influence of sea power.

To-day I would say without hesitation that the submarine has not replaced the battleship as the principal factor in Avar at sea. Taking it in its existing stage of development, a submersible vessel is useful for certain purposes only. It cannot yet be called sea-going or sea-keeping, it is not fast; and it is extremely vulnerable. Already devices for its destruction are multiplying: the aeroplane or dirigible can see it well below the surface; the net, the mine field, the destroyer are all being used to oppose it, and a new type of armed patrol-boat is being built for the purpose of watching the sea's surface for signs of the mechanical whale that must come up. Submarine signals, also, although now in the infancy of development will doubtless soon be able to detect the presence of moving submarines and give accurately their direction and distance.

It would be, of course, not unreasonable to suppose that, while the weapons for the destruction of underwater craft are being perfected, the improvement of the submarine itself will continue. Without doubt its size will increase, its engines, both surface and sub-surface, gain in horsepower and resulting speed, its radius of action grow and its sea-worthiness improve. I have said nothing of the discomfort of the officers and men on the present-day vessels, nor of the well known fact that the propelling and operating mechanism is in such an experimental stage that frequent accidents occur; these are the evils of any new apparatus—witness the automobile of fifteen years ago. But the time is not far distant when the "habitability" and safety from mishaps will make submarines as dependable as any other high-powered complicated vessel of war. Two deterring factors will probably always be present in its development: the inability to see under water, and the necessity of coming to the surface at short intervals.

he submarine has come to stay. It has taken its place, not as the sole weapon in naval offense and defense, but as an adjunct to other weapons. That it is useful for coast defense, for commerce destroying, for scouting purposes, and as a part of the protection to and attacking power of a battleship fleet is established. That it alone is capable of defending a coast against invasion is claimed only by the type of people in this country to whom national defense means preventing an enemy from landing an armed force on our Atlantic or Pacific seaboard—a Chinese wall kind of defense that requires necessarily the total abandonment of Alaska, of the Canal, of Hawaii and our other dependencies over seas, the stopping of our exports and imports and the inability to protect against aggression our citizens abroad and our well-considered international policies. In other words, free communications across the seas are just as much an integral part of our national defense as is the protection of New York harbor.

Before I became associated with our naval affairs in an official way, I had a theory that I knew much about naval strategy and warfare. But I have come very quickly to recognize that I did not: that war on the sea is a greatly complicated science, developing step by step through the faithful work of men who are trained through years of study and experience. It is therefore of interest that the very great majority of naval officers both here and abroad do not believe that the submarine has supplanted the battleship, even though the characteristics of the latter may greatly change. They hold that as it is improved step by step the submarine will take its place as one, but only one, of the many instruments of offense and defense on the seas; that it will fit in to its well-appointed place, and that history, with the devising of another weapon, will repeat itself.

© J. Fred MacDonald, 2013



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