21st Century Mahan: Sound Military Conclusions for the Modern Era
By Benjamin F. Armstrong
(Naval Institute Press, 240 pages, $26)

Alfred Thayer Mahan wrote about naval history, strategy, and geopolitics more than 100 years ago, yet, as Benjamin Armstrong points out in 21st Century Mahan: Sound Military Conclusions for the Modern Era (revised and expanded in the 2023 edition), the naval profession of today can still benefit from Mahan’s enduring insights about naval strategy and administration. We live in a globalized world with changing technology and shifting geopolitics — a world not that fundamentally different from Mahan’s. As Armstrong notes in his introduction, “The world of Mahan is today.”

The book is divided into eight chapters, all of which include an introductory piece by Armstrong and an essay by Mahan. The first chapter is probably the most important. Armstrong’s introductory essay is titled “America’s Place in the World,” which is followed by Mahan’s 1890 piece “The United States Looking Outward.” Mahan wrote this article eight years before the Spanish-American War resulted in the United States emerging as a global imperial power. Mahan noted that the “world continues to be one of struggle and vicissitude,” where globally “nation is arrayed against nation,” and foresaw the need for the United States to have a powerful navy, an alliance with Great Britain, an inter-oceanic canal in Central America, and control of the Hawaiian Islands. Our favorable geographic position between the “two Old Worlds” (Europe and Asia) had to be complemented by “military readiness,” Mahan wrote, because “[t]hough distant, our shores can be reached; being defenseless they can detain but a short time a force sent against them.”

“This essay,” Armstrong writes, “was the first of Mahan’s many forays into contemporary affairs and American national strategy. It foreshadowed many of the themes he would write about in the coming decades,” especially in The Problem of Asia and The Interest of America in International Conditions. Mahan understood that rising Asian powers, especially Japan but also China, would cause the United States to become an Asian power. In fact, Mahan later foresaw the importance to the global balance of power of the South China Sea, East China Sea, and the entire east Asian littoral, which he called the “Asiatic Mediterranean.”

Mahan also understood, with Clausewitz, that war is waged for political purposes and that the ends of war are victory on the field and seas of battle and the achievement of the political purpose. He explained this in his 1896 essay “Preparedness for Naval War.” The United States, he wrote, is an “insular power” that is “dependent … upon a navy.” We have “interests beyond the sea” that must be protected — and those interests are political in nature.

This means that the United States requires naval administration that “provides to the nation an efficient fighting body, directed by well-trained men, animated by a strong military spirit.” That was the subject of Mahan’s 1903 essay “The Principles of Naval Administration.” It also means that political considerations help to determine the “disposition” of naval power, which Mahan discussed in his 1902 article “Considerations Governing the Disposition of Navies.” One of those political considerations was the growing “interdependence of nations” — what we today call “globalization.” Other considerations included the commercial and financial interests of the country. The “interaction of commerce and finance,” he wrote, “shows a unity in the modern civilized world.” And he noted that our nation’s interests had “shifted” due to developments in the Far East, including the increased trade from Europe via the Red Sea, Indian Ocean, and the east Asian littoral. Preponderant naval power at key locations can “cut the sinews of the enemy’s power by depriving him of sea-borne commerce.” Here, Mahan could just as readily be discussing the geopolitics of the crucial maritime region that Robert D. Kaplan so brilliantly explored in Monsoon and Asia’s Cauldron.

The book’s final chapters are devoted to the training of officers and sailors, which was the subject of Mahan’s first publication in the U.S. Naval Institute’s Record of the United States Naval Institute, the forerunner of Proceedings, the institute’s flagship journal, and naval leadership as epitomized by Edward Pellew (later Adm. Lord Exmouth), who fought and commanded in the War of American Independence, the wars of the French Revolution and Empire, and struggles against the Barbary pirates off the North African coast; and by Adm. Lord Horatio Nelson, the victor of the Nile, Copenhagen, and Trafalgar. The essay on Nelson, “The Strength of Nelson,” is a historical and biographical masterpiece that emphasized his “conviction, confidence, trust, faith,” and, above all, his commitment to Duty. Mahan quotes Lord Minto: “[T]here was a sort of heroic cast about Nelson that I never saw in any other man, and which seems wanting to the achievement of impossible things, which became easy to him.” With all the advances of modern technology, there is still no substitute for naval leadership.

Mahan in all of his works emphasized the importance of the study of history, not, as Armstrong points out, because history repeats itself but rather because history imparts wisdom, counsels prudence, and offers guidance. That, above all, is why Mahan remains relevant to our 21st-century world.

Francis P. Sempa wrote introductions to two of Alfred Thayer Mahan’s books: The Problem of Asia (1900) and The Interest of America in International Conditions (1910).