(1) Its own communications, or those of its adversary (which correspond to the communications of armies operating ashore).  These tend to increase in importance strategically with the increasing hunger of modern fleets (for coal, ammunition, &c).

    (2) The communications of an army operating from an advanced oversea
    base, that is communication between the advanced and the main base.

(3) Trade Routes, that is the communications upon which depend the national resources and the supply of the main bases, as well as the “lateral” or connecting communications between various parts of belligerents’ possessions.

N.B.—­Such “lines of passage and communication” are the preoccupation of Naval Strategy; that is to say, problems of Naval Strategy can be reduced to terms of “passage and communication” and this is probably the best method of solving them.

NAVAL STRATEGY CONSIDERED AS A
QUESTION OF PASSAGE AND
COMMUNICATION

By “Naval Strategy” we mean the art of conducting the operations of the Fleet.  Such operations must always have for their object “passage and communication”; that is, the Fleet is mainly occupied in guarding our own communications and seizing those of the enemy.

PROOF I.—­Deductive.—­We say the aim of Naval Strategy is to get command of the sea.  What does this mean?  It is something quite different from the Military idea of occupying territory, for the sea cannot be the subject of political dominion or ownership.  We cannot subsist upon it (like an army on conquered territory), nor can we exclude neutrals from it.  Admiral Colomb’s theory of “conquest of water territory,” therefore, involves a false analogy, and is not safe as the basis of a strategical system.  What then is the value of the sea in the political system of the world?  Its value is as a means of communication between States and parts of States.  Therefore the “command of the sea” means the control of communications in which the belligerents are adversely concerned.

COROLLARY.—­The command of the sea can never be, like the conquest of territory, the ulterior object of a war, unless it be a purely maritime war, as were approximately our wars with the Dutch in the 17th century, but it may be a primary or immediate object, and even the ulterior object of particular operations.

PROOF II.—­Inductive, from history or past experience.—­History shows that the actual functions of the Fleet (except in purely maritime wars) have been threefold.

1.  The prevention or securing of alliances (i.e., deterring or persuading neutrals as to participating in the war).