, driven to
sea by mountains and desert at her back, spread her sails beyond
the Pillars of Hercules. And England, hemmed in by the Atlantic,
has carried her goods and her language to every nook and cranny of
the earth. Thus the ocean has served less to separate than to bring
together. As a common highway it has not only excited quarrels, but
established common interests between nations. Special agreements
governing the suppression of piracy and the slave trade, navigation
regulations and the like, have long since brought nations together in
peace on a common ground. It has also gone far to create international
law for the problems of war. Rules governing blockade, contraband,
and neutral rights have been agreed upon long since. But, as every
war has proved, international law has needed a higher authority to
enforce its rules in the teeth of a powerful belligerent. To remedy
this defect is one of the purposes of a League of Nations.

Such has been the significance of the sea. The nations who have
used it have made history and have laid the rest of the world under
their dominion intellectually, commercially, and politically. Indeed,
the story of the sea is the history of civilization.

At the conclusion of this survey, it is appropriate to pause and
summarize what is meant by the term "sea power." It is a catch
phrase, made famous by Mahan and glibly used ever since. What does
sea power mean? What are its elements?

Obviously it means, in brief, a nation's ability to enforce its will
upon the sea. This means a navy superior to those of its enemies.
But it means also strategic bases equipped for supplying a fleet
for battle or offering refuge in defeat. To these bases there must
run lines of communication guarded from interruption by the enemy.
Imagine, for instance, the Suez or the Panama Canal held by a hostile
force, or a battlefleet cut off from its fuel supply of coal or
oil.

The relation of shipping to sea power is not what it was in earlier
days. Merchantmen are indeed still useful in war for transport
and auxiliary service, but it is no longer true that men in the
merchant service are trained for man-of-war service. The difference
between them has widened as the battleship of to-day differs from
a merchantman of to-day. Nor can a merchantship be transformed
into a cruiser, as in the American navy of a hundred years ago.
The place of shipping in sea power is therefore subsidiary. In
fact, unless a nation can