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It is interesting to note how this simple fact is the key to most of the operations of strategy and tactics; how—the mechanical tools in the way of ships and guns and torpedoes having been supplied—the key to their successful use is simply to take advantage of all opportunities of isolating one part of the enemy’s force from the rest, and then attacking one of the parts with a force superior to it. Opportunities lacking, one must, of course, try to create opportunities by inducing the enemy to detach some part of his force, under circumstances such that you can attack it, or the weakened main body, with a superior force. Naturally, one must try to prevent a similar procedure by the enemy.
This does not mean that the sole effort of naval operations is finesse in either strategy or tactics; sometimes the sole effort is to force a pitched battle by the side that feels superior, and to avoid a pitched battle by the side that feels inferior. Before the actual inferiority or superiority has been ascertained, however, the strategy of each commander is to bring about a situation in which his force shall have the advantage. The advantage having been gained and recognized (or an advantage existing and being recognized), strategy insists on forcing a battle, for the reason that every contest weakens the loser more than it does the winner.
This does not mean that it is always wise to engage a weaker force that is temporarily separated from its main body. It is readily understandable, for instance, that it would be unwise in two cases: