Mahan on naval warfare

by A. T. Mahan

Where all three conditions, situation, intrinsic strength, and abundant resources, are found in the same place, it becomes of great consequence strategically and may be of the very first importance, though not always. For it must be remarked that there are other considerations, lesser in the purely military point of view, which enhance the consequence of a seaport even strategically; such as its being a great mart of trade, a blow to which would cripple the prosperity of the country; or the capital, the fall of which has a political effect additional to its importance otherwise.

I. Situation

Of the three principal conditions, the first, situation, is the most indispensable; because strength and resources can be artificially supplied or increased, but it passes the power of man to change the situation of a port which lies outside the limits of strategic effect.

Generally, value of situation depends upon nearness to a sea route; to those lines of trade which, when drawn upon the ocean common, are as imaginary as the parallels of the chart, yet as really and usefully exist. If the position be on two routes at the same time, that is, near the crossing, the value is enhanced. A cross-roads is essentially a central position, facilitating action in as many directions as there are roads. Those familiar with works on the art of land war will recognize the analogies. The value becomes yet more marked if, by the lay of the land, the road to be followed becomes very narrow; as at the Straits of Gibraltar, the English Channel, and in a less degree the Florida Strait. Perhaps narrowing should be applied to every inlet of the sea, by which trade enters into and is distributed over a great extent of country; such as the mouth of the Mississippi, of the Dutch and German rivers, New York harbor, etc. As regards the sea, however, harbors or the mouths of rivers are usually termini or entrepôts, at which goods are transshipped before going farther. If the road be narrowed to a mere canal, or to the mouth of a river, the point to which vessels must come is reduced almost to the geometrical definition of a point and near-by positions have great command. Suez presents this condition now, and Panama soon will.

Analogously, positions in narrow seas are more important than those in the great ocean, because it is less possible to avoid them by a circuit. If these seas are not merely the ends—“termini”—of travel but “highways,” parts of a continuous route; that is, if commerce not only comes to them but passes through to other fields beyond, the number of passing ships is increased and thereby the strategic value of the controlling points....

[Illustrations are here employed to show that, owing to the freedom of movements on the open sea, dangerous positions when not located in narrow channels are more easily avoided than on land. Hence “fausses routes et moments perdus,” in Napoleon’s phrase, play an important part in naval operations, as shown by Napoleon’s route to Egypt via Malta and Crete, and Rozhestvensky’s choice of routes before Tsushima. On the other hand, obstacles when they exist are impassable. Only submarines can avoid danger by transit over land.—Editor.]

II. Military Strength

A. Defensive Strength. [Military strength is considered in two aspects, (A) defensive, and (B) offensive. Under defensive strength, it is first pointed out that, as illustrated by Port Arthur and Santiago, coast bases are in chief danger of capture from the land side. While it is the business of the navy to prevent the landing of forces, its operations, though defensive in result, must be offensive in character, and not confined to the vicinity of the bases.—Editor.]

In the sphere of maritime war, the navy represents the army in the field; and the fortified strategic harbors, upon which it falls back as ports of refuge after battle or defeat, for repairs or for supplies, correspond precisely to strongholds, like Metz, Strasburg, Ulm, upon which, systematically occupied with reference to the strategic character of the theater of war, military writers agree the defense of a country must be founded. The foundation, however, must not be taken for the superstructure for which it exists. In war, the defensive exists mainly that the offensive may act more freely. In sea warfare, the offensive is assigned to the navy; and if the latter assumes to itself the defensive, it simply locks up a part of its trained men in garrisons, which could be filled as well by forces that have not their peculiar skill. To this main proposition I must add a corollary, that if the defense of ports, many in number, be attributed to the navy, experience shows that the navy will be subdivided among them to an extent that will paralyze its efficiency. I was amused, but at the same time instructed as to popular understanding of war, by the consternation aroused in Great Britain by one summer’s maneuvers, already alluded to, and the remedy proposed in some papers. It appeared that several seaports were open to bombardment and consequent exaction of subsidies by a small squadron, and it was gravely urged that the navy should be large enough to spare a small detachment to each port. Of what use is a navy, if it is to be thus whittled away? But a popular outcry will drown the voice of military experience.

... The strictly defensive strength of a seaport depends therefore upon permanent works, the provision of which is not the business of naval officers. The navy is interested in them because, when effective, they release it from any care about the port; from defensive action to the offensive, which is its proper sphere.