umption can be
accepted without very careful consideration. In the history of that system
there is no indication that it was affected by the volume of the trade it
was designed to protect. Nor has any one succeeded in showing that the
pressure which an enemy could exert upon us through our commerce increased
in effect with the volume of our seaborne trade. The broad indications
indeed are the other way--that the greater the volume of our trade, the
less was the effective impression which an enemy could make upon it, even
when he devoted his whole naval energies to that end. It is not too much to
say that in every case where he took this course his own trade dwindled to
nothing, while ours continually increased.

It may be objected that this was because the only periods in which he
devoted his main efforts to trade destruction were when we had dominated
his navy, and being no longer able to dispute the command, he could do no
more than interfere with its exercise. But this must always be so whether
we have positively dominated his navy or not. If he tries to ignore our
battle-fleets, and devotes himself to operations against trade, he cannot
dispute the command. Whatever his strength, he must leave the command to
us. He cannot do both systematically, and unless he attacks our trade
systematically by sustained strategical operation, he cannot hope to make
any real impression.

If, now, we take the two assumptions and test them by the application of
elementary principles, both will appear theoretically unsound. Let us take
first the relation of vulnerability to volume. Since the object of war is
to force our will upon the enemy, the only way in which we can expect war
on commerce to serve our end is to inflict so much damage upon it as will
cause our enemy to prefer peace on our terms to a continuation of the
struggle. The pressure on his trade must be insupportable, not merely
annoying. It must seriously cripple his finance or seriously threaten to
strangle his national life and activities. If his total trade be a hundred
millions, and we succeed in destroying five, he will feel it no more than
he does the ordinary fluctuations to which he is accustomed in time of
peace. If, however, we can destroy fifty millions, his trade equilibrium
will be overthrown, and the issue of the war will be powerfully affected.
In other words, to affect the issue the impression made on trade must be a
percentage or relative impression. The m