Mahan
has estimated that during the whole of the war of the French Revolution
and Empire the direct loss to England "by the operation of hostile
cruisers did not exceed 2-1/2 per cent. of the commerce of the Empire;
and that this loss was partially made good by the prize ships and
merchandise taken by its own naval vessels and privateers." It should be
noted, however, that the Royal Commission on Food Supply was of opinion
that 4 per cent. would be a more accurate estimate. It is also well
known that during the same period the maritime commerce of England was
doubled in volume while that of France was annihilated. In point of fact
the risks run in war by commerce afloat are measured very exactly by the
degree in which the flag which covers it has secured the command of the
sea--that is, be it always remembered, the control of the maritime
communications affected. During the War of American Independence, when
British supremacy at sea was seriously challenged and at times was in
grave jeopardy--owing quite as much to faulty disposition as to
inferiority of force--premiums of fifteen guineas per cent. were paid in
1782 on ships trading to the Far East; whereas from the spring of 1793
until the close of the struggle with Napoleon no premiums exceeding half
that rate were paid. Yet to the very end of the war British merchant
vessels were being seized even in the Channel almost every day. There
is, however, good reason to think that many of these seizures were in
reality collusive operations undertaken for the purpose of carrying on
clandestinely the direct trade with the Continent which Napoleon sought
in vain to suppress. The full history of the memorable conflict between
the Berlin Decrees of Napoleon and the British Orders in Council, is
still to be written. Some very illuminating side-lights are thrown on it
by Mr David Hannay in a volume entitled _The Sea-Trader, His Friends and
Enemies_.

It would seem to follow from these premisses--fortified as they are by
other historical examples that might be cited--that of two belligerents
in a naval war, that one which establishes and maintains an effective
command of the sea will be absolute master of the maritime commerce of
the other, while his own maritime commerce, though not entirely immune,
will suffer no such decisive losses as will determine or even materially
affect the course and issue of the war; and that he may indeed emerge
from the war much stronger and more pros