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.
It would seem to have been the evil influence of this travestied maxim which had much to do with the cramped and timorous strategy of the Americans in their late war with Spain. They had ample naval force to secure such a local and temporary command of the Gulf of Mexico as to have justified them at once in throwing all the troops they had ready into Cuba to support the insurgents, in accordance with their war plan. They had also sufficient strength to ensure that the communications with the expeditionary force could not be interrupted permanently. And yet, because the Spaniards had an undefeated fleet at sea somewhere, they hesitated, and were nearly lost. The Japanese had no such illusions. Without having struck a naval blow of any kind, and with a hostile fleet actually within the theatre of operations, they started their essential military movement oversea, content that though they might not be able to secure the control of the line of passage, they were in a position to deny effective control to the enemy. Our own history is full of such operations. There are cases in plenty where the results promised by a successful military blow oversea, before permanent command had been obtained, were great enough to justify a risk which, like the Japanese, we knew how to minimise by judicious use of our favourable geographical position, and of a certain system of protection, which must be dealt with later.