How to Hide an Empire: A History of the Greater United States

by Daniel Immerwahr

Roosevelt might have taken this as cause for despair. Yet just as he was reading Frederick Jackson Turner’s warnings about the end of the frontier, he was also studying the work of another historian, Captain Alfred Thayer Mahan, of the Naval War College. Mahan’s lengthy 1890 treatise, The Influence of Sea Power upon History, was hardly a page-turner, but it contained a powerful suggestion. If, according to Turner, the land was closed, Mahan noted that the seas were open. Mahan didn’t care about democracy or individualism, as Turner did. His concern was trade. The wealth of nations, he argued, came from maritime commerce. Yet ships could not simply cast off for distant lands. They needed ports, coaling stations, warehouses, and other way stations along their paths. They also needed naval protection, which required still more overseas bases.