length and difficulty of the enemy's land communications and to the
strategical situation of the territory at stake.

These examples will also serve to illustrate and enforce the second
essential of this kind of war. As has been already said, for a true limited
object we must have not only the power of isolation, but also the power by
a secure home defence of barring an unlimited counterstroke. In all the
above cases this condition existed. In all of them the belligerents had no
contiguous frontiers, and this point is vital. For it is obvious that if
two belligerents have a common frontier, it is open to the superior of
them, no matter how distant or how easy to isolate the limited object may
be, to pass at will to unlimited war by invasion. This process is even
possible when the belligerents are separated by a neutral State, since the
territory of a weak neutral will be violated if the object be of sufficient
importance, or if the neutral be too strong to coerce, there still remains
the possibility that his alliance may be secured.

We come, then, to this final proposition--that limited war is only
permanently possible to island Powers or between Powers which are separated
by sea, and then only when the Power desiring limited war is able to
command the sea to such a degree as to be able not only to isolate the
distant object, but also to render impossible the invasion of his home
territory.

Here, then, we reach the true meaning and highest military value of what we
call the command of the sea, and here we touch the secret of England's
success against Powers so greatly superior to herself in military strength.
It is only fitting that such a secret should have been first penetrated by
an Englishman. For so it was, though it must be said that except in the
light of Clausewitz's doctrine the full meaning of Bacon's famous aphorism