Admiral Mahan, an acute political observer as well as strategist, summed up the international situation in 1895 and again in 1897 as "an equilibrium on the [European] Continent, and, in connection with the calm thus resulting, an immense colonizing movement in which all the great powers were concerned."[1] Later, in 1911, he noted that colonial rivalries had again been superseded by rivalries within Europe, but pointed out that the European tension was itself largely the product of activities and ambitions in more distant spheres. In fact the international developments of recent times, whether in the form of colonial enterprises, armament competition, or actual warfare, find a common origin in economic and commercial interests. Commerce and quick communications have drawn the world into closer unity, yet by a kind of paradox have increased the possibilities of conflict. Both by their common origin and by their far-reaching consequences, it is thus possible to connect the story of naval events from the Spanish-American to the World War, and to gather them up under the general title, "rivalry for world power." 1. THE SPANISH-AMERICAN WAR To this rivalry the United States could hardly hope or desire to remain always a passive spectator, yet, aside from trying to stabilize the western hemisphere by the Monroe Doctrine, she cherished down to the year 1898 a policy of isolation from world affairs. During the first half of the 19th century, it is true, her interests were directed outward by a flourishing merchant marine. In 1860 the American merchant fleet of 2,500,000 tons was second only to Great Britain's and nearly equal to that of all other nations combined. But its decay had already begun, and continued rapidly. The change from wood to iron construction enabled England to build cheaper ships; and American shipping suffered also from lack of government patronage, diversion of capital into mare profitable projects of Western development, and loss of a third of its tonnage by destruction or shift to foreign register during the Civil War. At the outbreak of that war 72 per cent of American exports were carried in American bottoms; only 9 per cent in 1913. Thus the United States had reached the unsatisfactory condition of a nation with a large and rapidly growing foreign commerce and an almost non-existent merchant marine. [Footnote 1: NAVAL STRATEGY, p. 104.]