But even in the past, while the importance of the merchant service was
considerable in the ways just outlined, it may perhaps be questioned
whether it formed an element of _sea power_, in the sense in which
Mahan discussed sea power. The power of every country depends on all
the sources of its wealth: on its agriculture, on its manufacturing
activities, and even more directly on the money derived from exports.
But these sources of wealth and all sources of wealth, including
the merchant service, can hardly be said to be elements of power
themselves, but rather to be elements for whose protection power
is required.

In fact, apart from its usefulness in furnishing auxiliaries, it
seems certain that the merchant service has been an element of
_weakness_. The need for navies arose from the weakness of merchant
ships and the corresponding necessity for assuring them safe voyages
and proper treatment even in time of peace; while in time of war
they have always been an anxious care, and have needed and received
the protection of fighting ships that have been taken away from
the fleet to act as convoys.

If commercial sea power was not the power meant by Mahan, then he
must have meant naval power. And if one reads the pages of history
with patient discrimination, the conviction must grow on him that
what really constituted the sea power which had so great an influence
on history, was _naval_ power; not the power of simply ships upon
the sea, but the power of a navy composed of ships able to fight,
manned by men trained to fight, under the command of captains skilled
to fight, and led by admirals determined to fight. Trafalgar was
not won by the merchant service; nor Mobile, Manila, or Tsushima.