In the American rise to world power, which began in the 1890s, one man who was neither president nor secretary of state played a crucial role. Captain Alfred Thayer Mahan, naval strategist and historian, provided the theoretical framework for the extension of American power into the Pacific as the key to national security and world peace. If Seward can be called the precursor of American imperialism, then Mahan was its prophet. Mahan's influence upon American foreign policy is easy to demonstrate because he was so visible. His first book, The Influence of Sea Power Upon History, 1660–1783, achieved an instant success when it was published in 1890, and it had an effect on the Anglo-American world comparable with Charles Darwin's Origin of Species a generation earlier. A rising group of dynamic, nationalistic American leaders pondered Mahan and became his fervent disciples.
Theodore Roosevelt brought to the presidency a coherent program for the expansion of American power. The ideas of Mahan formed Roosevelt's frame of reference in almost all his discussions of foreign policy: a large navy that could control the sea-lanes; the acquisition of naval bases and coaling stations, and possibly colonies; the construction of an isthmian canal to connect the Atlantic and Pacific oceans by water, with bases to guard the approaches on either side; and the development of a large merchant marine to expand American foreign trade. By tireless propaganda (Roosevelt described the presidency as "a bully pulpit"), cajolery of Congress, and often by breathtaking expansion of presidential powers, Roosevelt was able to realize Mahan's program. Although it was not as large as he wished, he built the "Great White Fleet" and sent it around the world. He acquired naval bases in Cuba and the Philippines, and he carried out what Secretary of State Elihu Root described as the rape of Colombia in order to build the Panama Canal.
Personally much closer to Roosevelt was Senator Henry Cabot Lodge of Massachusetts who was also a disciple of Mahan. Lodge thought as Roosevelt did and consistently supported him in his imperialistic initiatives. Other notable members of Roosevelt's circle of intimates were the brothers Brooks and Henry Adams, grandsons and great-grandsons of the Massachusetts presidents. They were historians, as was the president himself, and they shared his expansionist views without, however, possessing his ebullient optimism.
If foreign policy had always been an unpleasant distraction to American government officials, it was so no longer. The administrations of Theodore Roosevelt were the turning point, and the hopes of Mahan, Lodge, the Adamses, and Roosevelt himself for the growth of American power and influence were realized. The War with Spain, which Roosevelt and his friends had promoted so ardently, and World War I, even more so, thrust the United States into a commanding world position.