s his enemy, the less is
he likely to be hurt himself. This defines the great principle
of offensive defence. To act in accordance with this principle,
a belligerent should try, as the saying goes, to carry the war
into the enemy's country. He should try to make his opponents
fight where he wants them to fight, which will probably be as
far as possible from his own territory and as near as possible
to theirs. Unless he can do this, invasion and even serious raids
by him will be out of the question. More than that, his inability
to do it will virtually indicate that on its part the other side
can fix the scene of active hostilities unpleasantly close to
the points from which he desires to keep its forces away.

A line of ocean communications may be vulnerable throughout its
length; but it does not follow that an assailant can operate
against it with equal facility at every point, nor does it follow
that it is at every point equally worth assailing. Lines running
past hostile naval ports are especially open to assault in the
part near the ports; and lines formed by the confluence of two or
more other lines--like, for example, those which enter the English
Channel--will generally include a greater abundance of valuable
traffic than others. Consequently there are some parts at which
an enemy may be expected to be more active than elsewhere, and
it is from those very parts that it is most desirable to exclude
him. They are, as a rule, relatively near to the territory of the
state whose navy has to keep the lines open, that is to say,
prevent their being persistently beset by an enemy. The necessary
convergence of lines towards that state's ports shows that some
portion of them would have to be traversed, or their traversing
be attempted, by expeditions meant to carry out either invasion
or raids. If, therefore, the enemy can be excluded as above
mentioned, invasions, raids, and the more serious molestation of
sea-borne commerce by him will be prevented.

If we consider particular cases we shall find proof upon proof
of the validity of the rule. Three great lines--one from the
neighbourhood of the Cape of Good Hope, one from the Red Sea, and
a third from India and Ceylon--converge near the south-western
part of Australia and run as one line towards the territory of the
important states farther east. If an assailant can be excluded
from the latter or combined line he must either divide his force
or operate on only one of t