The first effort on hearing of the departure of the hostile fleet will be, of course, to get our fleet out to sea, reinforced as much as practicable, by our reserve ships; and to get the coast-guard on their patrol stations. As we should not know the destination of the enemy, we should either have to assume a destination and send our fleet to that place (leaving the other places undefended) or else send our fleet out to sea to some position from which it would despatch scouts in different directions to intercept the enemy, in order that our fleet might meet it and prevent its farther advance.
Of course, the latter procedure could not be carried out reasonably, unless we had a great enough number of trained scouts to make the interception of the enemy fleet probable; because otherwise the probabilities would be that an enemy having the battle cruisers and scouts that European navies have, would succeed in evading our fleet and landing a force upon our shores; and it could not be carried out reasonably either, if we knew that our fleet was markedly inferior to the coming fleet; because to send out our fleet to meet a much more powerful one in actual battle would be to commit national suicide by the most expeditious method.
In case the departure of the enemy fleet occurred in the stormy months of the winter, we might feel warranted in guessing that its immediate destination was the Caribbean; yet if our fleet were in the Caribbean at the time, and if our coast lacked shore defenses as at present, we might argue that the enemy would take the opportunity to make a direct descent upon our coast, seize a base—say on the eastern end of Long Island—and march directly on New York. It would be very difficult to plan the development of a line of scouts in such a way that the scouts would intercept an attack directed at some unknown point between Boston and the West Indies, perhaps in the southern part of the West Indies—say Margarita Island. In fact, it would be impossible; with the result that, unless we intercepted it by simple good luck, the enemy would succeed in landing a force on our eastern coast, or else in the seizing of a base in the West Indies or the southern part of the Caribbean Sea.
Either one of these acts, successfully performed by an enemy, would give him an advantage; that is, it would make his position relatively to ours better than it was before. It would have the same effect, therefore, as winning a battle; in fact it would constitute the winning of a battle—not a physical battle but a strategic battle.
It may be objected that, unless we knew our fleet to be more powerful it would be wiser and more comfortable for all concerned to withdraw our ships to the shelter of their bases, and let the enemy do his worst—on the theory that he could not do anything else so ruinous to us as to sink our fleet.
There is of course considerable reasonableness in this point of view; and strategy declares the unwisdom of engaging in battles that are sure to be lost. It must be remembered, however, that the coming fleet will operate at a considerable strategic disadvantage, owing to the necessity for guarding the "train" of auxiliary ships that will come with it, holding fuel and supplies of various kinds; that this handicap will offset a considerable advantage in offensive strength; and that the handicap will be still greater if the enemy fleet have near it a flotilla of transports carrying troops. It must be remembered also that in all probability, we should not have detailed information as to the number of vessels coming, and should not really know whether it was superior to ours or not: though we should be justified in assuming that the coming fleet believed itself to be superior to ours in actual fighting power. Absence of trustworthy information on such points is usual in warfare, and is one of the elements that is the most difficult to handle. The Navy Department would be more able to form a correct estimate on this point than the commander-in-chief until such time as our scouts might come into absolute contact with the enemy's main body; but, until then, all that the department and fleet would know would be that a large hostile force had left Europe. They would not know its size or destination.
Clearly, the first thing we should need would be information. To get this after war has broken out, the only means is scouts.
Scouting and Screening.—Scouts are needed by every navy; but they are most needed by a navy that has a very long coast-line to protect. If the great commercial centres and the positions that an enemy would desire for advanced bases along the coast, have local defenses adequate to keep off a hostile fleet for, say, two weeks, the urgency of scouts is not quite so absolute; since, even if the hostile fleet evades our scouts and our fleet, and reaches our shores, our fleet will have two weeks in which to get to the place attacked. But if the coast is not only long but also unguarded by shore defenses, the urgency is of the highest order.
If we knew our fleet to be the weaker, but if we did not believe it to be so much the weaker as to force it to seek safety in flight, our natural plan would be that of Napoleon's in Italy in 1797—to keep our force together, and to hurl it against detached parts of the enemy's force, whenever possible. This plan might not be difficult of execution, if the enemy were accompanied by his train of auxiliary and supply ships; since such ships are vulnerable to almost any kind of attack, have almost no means of defense whatever, and therefore require that a part of the fighting force of the main body be detached to guard them. Whether the enemy would have his train quite close to him, or a day's steaming behind, say 240 miles, we should not, of course, know.
How could we ascertain?