need only be mentioned here in order to be carefully distinguished from the latter. Any nation seeking to exercise or secure the command of the sea in this sense would in so doing engage in an act of war, and would be regarded as so engaging by any other nation whose rights and interests were in any way affected by the act. Hence the difference between the two is plain. The claim to the sovereignty of the seas and the exaction of the ceremonial observance--the lowering of a flag or a sail--which symbolized it, was not in itself an act of war, though it might lead to war if the claim were resisted. An attempt to assert or secure the command of the sea is, on the other hand, in itself an act of war and would never be made by any nation not prepared to take the consequence in the instant outbreak of hostilities. For what is it that a nation seeks to do when it attempts to exercise or secure the command of the sea? It seeks to do nothing more and nothing less than to deny freedom of access to the waters in dispute to the ships, whether warships or merchant ships, of some other nation. It denies the common right of highway, which is the essential attribute of the sea, to that other nation, and seeks to secure the monopoly of that right for itself. In other words, it seeks to drive its adversary's warships from the sea, and either by the capture of his merchant vessels to appropriate the wealth they contain or by destroying them to deprive the adversary of its enjoyment. This is all that naval warfare as such can do. If the enemy is not constrained by the destruction of his warships and the extinction of his maritime commerce to submit to his victorious adversary's will, other agencies, not exclusively naval in character, must be employed to bring about that consummation. This means that military force must be brought into operation, either for the invasion of the defeated adversary's territory or for the occupation of some of his possessions lying across the seas, if he has any. If he has none, or if such as he has are not worth taking or holding--either as a permanent possession or as what is called a material guarantee to be used in the subsequent negotiations for peace--then the only alternative is invasion. But that is a subject which demands a chapter to itself.