he confluents, leaving the rest free.
The farther he can be pushed back from the point of confluence
the more effectually will he be limited to a single line, because
the combining lines, traced backwards, trend more and more apart,
and it is, therefore, more and more difficult for him to keep
detachments of his force within supporting distance of each other
if they continue to act against two or more lines. The particular
case of the approaches to the territory of the United Kingdom
has the same features, and proves the rule with equal clearness.
This latter case is so often adduced without mention of others,
that there is some risk of its being believed to be a solitary
one. It stands, however, exactly on all fours with all the rest
as regards the principle of the rule.

A necessary consequence of an enemy's exclusion from the combined
line as it approaches the territory to be defended is--as already
suggested--that invasion of that territory and serious raids
upon it will be rendered impracticable. Indeed, if the exclusion
be absolutely complete and permanent, raids of every kind and
depredations on commerce in the neighbourhood will be prevented
altogether. It should be explained that though lines and
communications are spoken of, it is the area crossed by them
which is strategically important. A naval force, either guarding
or intending to assail a line, does not necessarily station itself
permanently upon it. All that it has to do is to remain, for the
proper length of time, within the strategic area across which the
defended or threatened line runs. The strategic area will be of
varying extent, its boundaries being determined by circumstances.
The object of the defence will be to make the area from which the
enemy's ships are excluded as extensive as possible. When the
enemy has been pushed back into his own waters and into his own
ports the exclusion is strategically complete. The sea is denied
to his invading and important raiding expeditions, and indeed to
most of his individual cruisers. At the same time it is free
to the other belligerent. To effect this a vigorous offensive
will be necessary.

The immediate theatre of operations, the critical strategic area,
need not be, and often ought not to be, near the territory defended
by our navy. It is necessary to dwell upon this, because no principle
of naval warfare has been more frequently or more seriously
misapprehended. Misapprehension of it has led to mi