7. Strategic Lines

Communications

The most important of strategic lines are those which concern the communications. Communications dominate war. This has peculiar force on shore, because an army is immediately dependent upon supplies frequently renewed. It can endure a brief interruption much less readily than a fleet can, because ships carry the substance of communications largely in their own bottoms. So long as the fleet is able to face the enemy at sea, communications mean essentially, not geographical lines, like the roads an army has to follow, but those necessaries, supplies of which the ships cannot carry in their own hulls beyond a limited amount. These are, first, fuel; second, ammunition; last of all, food. These necessaries, owing to the facility of water transportation as compared with land, can accompany the movements of a fleet in a way impossible to the train of an army. An army train follows rather than accompanies, by roads which may be difficult and must be narrow; whereas maritime roads are easy, and inimitably wide.

Nevertheless, all military organizations, land or sea, are ultimately dependent upon open communications with the basis of the national power; and the line of communications is doubly of value, because it usually represents also the line of retreat. Retreat is the extreme expression of dependence upon the home base. In the matter of communications, free supplies and open retreat are two essentials to the safety of an army or of a fleet. Napoleon at Marengo in 1800, and again at Ulm in 1805, succeeded in placing himself upon the Austrian line of communication and of retreat, in force sufficient to prevent supplies coming forward from the base, or the army moving backward to the base. At Marengo there was a battle, at Ulm none; but at each the results depended upon the same condition,—the line of communication controlled by the enemy. In the War of Secession the forts of the Mississippi were conquered as soon as Farragut’s fleet, by passing above, held their line of communications. Mantua in 1796 was similarly conquered as soon as Napoleon had placed himself upon the line of retreat of its garrison. It held out for six months, very properly; but the rest of the campaign was simply an effort of the outside Austrians to drive the French off the line, and thus to reinforce the garrison or to enable it to retreat.

Importance of Sea Communications

Except Russia and Japan, the nations actively concerned in this great problem [the problem of Asia] rest, for home bases, upon remote countries. We find therefore two classes of powers: those whose communication is by land, and those who depend upon the sea. The sea lines are the most numerous and easy, and they will probably be determinative of the courses of trade. Among them there are two the advantages of which excel all others—for Europe by Suez, from America by way of the Pacific Ocean. The latter will doubtless receive further modification by an isthmian canal, extending the use of the route to the Atlantic seaboard of America, North and South.

Communications dominate war; broadly considered, they are the most important single element in strategy, political or military. In its control over them has lain the pre-eminence of sea power—as an influence upon the history of the past; and in this it will continue, for the attribute is inseparable from its existence. This is evident because, for reasons previously explained, transit in large quantities and for great distances is decisively more easy and copious by water than by land. The sea, therefore, is the great medium of communications—of commerce. The very sound, “commerce,” brings with it a suggestion of the sea, for it is maritime commerce that has in all ages been most fruitful of wealth; and wealth is but the concrete expression of a nation’s energy of life, material and mental. The power, therefore, to insure these communications to one’s self, and to interrupt them for an adversary, affects the very root of a nation’s vigor, as in military operations it does the existence of an army, or as the free access to rain and sun—communication from without—does the life of a plant. This is the prerogative of the sea powers; and this chiefly—if not, indeed, this alone—they have to set off against the disadvantage of position and of numbers under which, with reference to land power, they labor in Asia. It is enough. Pressure afar off—diversion—is adequate to relieve that near at hand, as Napoleon expected to conquer Pondicherry on the banks of the Vistula. But if the sea powers embrace the proposition that has found favor in America, and, by the concession of immunity to an enemy’s commerce in time of war, surrender their control of maritime communications, they will have abdicated the scepter of the sea, for they will have abandoned one chief means by which pressure in one quarter—the sea—balances pressure in a remote and otherwise inaccessible quarter. Never was moment for such abandonment less propitious than the present, when the determination of influence in Asia is at stake.