It will be seen, therefore, that in naval warfare, however closely we may concentrate our efforts on the destruction of our enemy's armed forces as the direct means to his overthrow, it would be folly to stay our hands when opportunities occur, as they will automatically, for undermining his financial position on which the continued vigour of those armed forces so largely depends. Thus the occupation of our enemy's sea communications and the confiscatory operations it connotes are in a sense primary operations, and not, as on land, secondary.
Such, then, are the abstract conclusions at which we arrive in our attempt to analyse the idea of command of the sea and to give it precision as the control of common communications. Their concrete value will appear when we come to deal with the various forms which naval operations may take, such as, "seeking out the enemy's fleet," blockade, attack and defence of trade, and the safeguarding of combined expeditions. For the present it remains to deal with the various kinds of sea command which flow from the communication idea.
If the object of the command of the sea is to control communications, it is obvious it may exist in various degrees. We may be able to control the whole of the common communications as the result either of great initial preponderance or of decisive victory. If we are not sufficiently strong to do this, we may still be able to control some of the communications; that is, our control may be general or local. Obvious as the point is, it needs emphasising, because of a maxim that has become current that "the sea is all one." Like other maxims of the kind, it conveys a truth with a trail of error in its wake. The truth it contains seems to be simply this, that as a rule local control can only avail us temporarily, for so long as the enemy has a sufficient fleet anywhere, it is theoretically in his power to overthrow our control of any special sea area.
It amounts indeed to little more than a rhetorical expression, used to emphasise the high mobility of fleets as contrasted with that of armies and the absence of physical obstacles to restrict that mobility. That this vital feature of naval warfare should be consecrated in a maxim is well, but when it is caricatured into a doctrine, as it sometimes is, that you cannot move a battalion oversea till you have entirely overthrown your enemy's fleet, it deserves gibbeting. It would be as wise to hold that in war you must never risk anything.