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.