The Interest of America in Sea Power, Present and Future

The Influence of Sea Power upon History (1890) and its 1892 sequel were historical studies demonstrating sea power's role in past conflicts. The Interest of America in Sea Power, published in 1897, is prescriptive rather than historical. Mahan moves from analyzing what sea power accomplished in the past to advocating what the United States must do in the present: acquire Hawaii, build an isthmian canal, establish Caribbean naval bases, and fund a modern battle fleet. The shift reflects Mahan's growing role as a public advocate, not merely a naval historian.

Mahan argued for the annexation of Hawaii as a mid-Pacific coaling station and naval base essential for defending the West Coast and projecting power toward Asia. He advocated for Caribbean footholds—Cuba and Puerto Rico—to secure the approaches to a future Central American canal. He also stressed the strategic importance of the Gulf of Mexico and the Caribbean Sea as an 'American Mediterranean' that the United States must control. These positions, he argued, were not imperial luxuries but necessary infrastructure for any nation seeking sea power and global commercial access.

For Mahan, a canal across the Isthmus would transform the United States into a two-ocean power, enabling rapid concentration of naval forces between the Atlantic and Pacific. Without a canal, the U.S. Navy would be divided between two coasts and incapable of decisive action in either theater. The canal would also enable American commercial vessels to compete more effectively in Asian markets. Mahan saw control over the canal's approaches—the Caribbean and the Gulf of Mexico—as inseparable from the canal itself. This argument directly shaped American policy toward Central America in the following decade.

The Influence of Sea Power upon History (1890) and its 1892 sequel were historical studies demonstrating sea power's role in past conflicts. The Interest of America in Sea Power, published in 1897, is prescriptive rather than historical. Mahan moves from analyzing what sea power accomplished in the past to advocating what the United States must do in the present: acquire Hawaii, build an isthmian canal, establish Caribbean naval bases, and fund a modern battle fleet. The shift reflects Mahan's growing role as a public advocate, not merely a naval historian.

The essays, originally published in magazines such as the Atlantic Monthly and Harper's, were written to build public support for naval expansion. Mahan's friend and admirer Theodore Roosevelt, then Assistant Secretary of the Navy, was already sympathetic to these views. The Spanish-American War of 1898 and the subsequent acquisition of Hawaii, Puerto Rico, Guam, and the Philippines largely realized Mahan's program. He served as a naval advisor to Roosevelt during the war. The book's lasting significance is as a manifesto for the strategic vision that guided American expansion at the turn of the century.

Mahan subordinated commerce to strategy. Scholars have noted that when he defended the 'Open Door' policy in China, his motives were political and security-related, not commercial. He valued overseas bases for their strategic advantages—coaling, repair, and projection—more than for their direct economic benefits. This reflects the primacy of security and foreign policy considerations in Mahan's thought. The merchant marine mattered because it supported the navy, not as an end in itself. His vision was fundamentally strategic: sea power as the foundation of national security and great-power status.