A truer definition is, “the area, whether of sea or land or both, within which the enemy must be overpowered before we can secure the object of the particular operation.”

Consequently, since the nature of the war varies with the object, it may be defensive in one theatre of operations and offensive in another.

Where the operations are defensive in character any special movement or movements may be offensive.

OBJECTIVE

An objective is “any point or force against which an offensive movement is directed.”  Thus where the object in any theatre of operation is to get command of a certain sea in which the enemy maintains a fleet, that fleet will usually be the objective.

LINES OF OPERATION

A line of operation is “the area of land or sea through which we operate from our base or starting point to reach our objectives.”

Lines of operation may be exterior or interior.  We are said to hold the interior lines when we hold such a position, in regard to a theatre of operations, that we can reach its chief objective points, or forces, more quickly than the enemy can move to their defence or assistance.  Such a position is called an interior position.  “Exterior Lines” and “Exterior Position” are the converse of these.

LINES OF COMMUNICATION

This expression is used of three different things:—­

    (1) Lines of supply, running from the base of operations to the point
    which the operating force has reached.

    (2) Lines of lateral communication by which several forces engaged in
    one theatre of operations can communicate with each other and move to
    each other’s support.

    (3) Lines of retreat, which are lines of supply reversed, i.e.,
    leading back to the base.

These three ideas are best described by the term “lines of passage and communication,” which we had in use at the end of the eighteenth century.

Ashore, lines of passage and communication are roads, railways, waterways, &c.

At sea, they may be regarded as those waters over which passes the normal course of vessels proceeding from the base to the objective or the force to be supplied.

In Land Strategy the great majority of problems are problems of communication.  Maritime Strategy has never been regarded as hinging on communications, but probably it does so even more than Land Strategy, as will appear from a consideration of maritime communications, and the extent to which they are the main preoccupation of Naval operations.

MARITIME COMMUNICATIONS

The various kinds of Maritime Communications for or against which a fleet may have to operate are:—­