Julian Corbett and Alfred Thayer Mahan found themselves at a pivotal point in history. The rapid increase in overseas trade in the early 20th century led lawmakers across the globe to seriously consider the implications of trade interdiction. On the eve of the 1907 Hague Convention, Mahan and Corbett presented their thoughts on this subject, writing to the same audience at the same time, a rarity indeed. In reading these essays, it is clear these two men had fundamentally different ideas on the international economy worked and thus possessed different perspectives on how the application of sea power on a day-to-day level. Where Mahan grappled with the dynamism of a globalized economy to understand its “pressure points” and apply sea power more effectively, Corbett, by contrast, took no account of this transformative economic development.
If a war should occur in the near future between the United States and China, the U.S. Navy should again explore the significance of trade interdiction as a strategy of war in the global economy. In a January 2020 Proceedings article, Daniel Ward proposed that Sir Julian Corbett’s 1911 work, Some Principles of Maritime Strategy, offers the best model for developing such a strategy, and suggested “the United States must disengage itself from the allure of Alfred Thayer Mahan” and, instead, embrace “Corbett’s concepts of blockade, ‘cruisers,’ and attacks on trade as more sensible options for containing and strangling China in a possible war.”1
However, in reading Mahan’s works carefully, particularly his later works, one sees that the effective interdiction of commerce underpins his entire theory of sea power. Battle by battlefleets is only a means to the ultimate end, which is to control the commons through blockade, i.e., effective trade interdiction. In developing this framework, Mahan acknowledged the growing importance of a globalized trade system to the application of sea power.
A Globalized Economy
By the early 20th century, the world economy had been transformed through a process known today as globalization. Ships-of-sail developed into ships-of-steam; on land, the agricultural economies in the Western world industrialized. As technologies and societies developed, the cost of shipping goods dropped substantially.2 The distance ships could travel, coupled with reduced shipping costs, “made it economically practicable to transport bulk commodities, or staples with a low value-to-weight ratio, over great distances. . . . Delivery was not only cheaper, moreover, but also quicker and more reliable.”3
Meanwhile, the rapid development of undersea cables amplified communication technology, which “profoundly changed the ways in which business was conducted and commerce transacted on a day-to-day level.”4 Individuals became reliant on the security of global trade for daily needs. It was as true then as it is today that often it is cheaper to buy goods from thousands of miles away than tens of miles. National economies diverged from self-sufficiency as the growing interdependence in the global trading system undermined the demand for localized provisioning.
Today’s international economy resembles that of the early 20th century to a surprising degree. Individual national economies across the globe again have morphed into a complex web in which each strand ensures the strength and fidelity of the other. Then as now, the globalized trade system is characterized by “constant movement—flows, or currents, of information, capital, goods, and people.”5 The relative importance of international trade to individual national economies is as high today as it was then—more than 20 percent. Moreover, 95 percent of modern-day commerce by volume is carried by sea, as it was then. Really, “international trade” is sea commerce—which is the essence of the global economy. The Navy should do more to remind everyone of this fundamental fact.
A globalized, interdependent economy is quite fragile. It is a web of dynamic, changing commercial lanes. The shifting variables exponentiate the number of factors to consider in understanding its complexity and functionality. Producers and consumers alike rely on a steady supply of goods; any interruption in the supply inhibits the production of wealth. Even the slightest deviation sends ripples through the entire system, deranging flows and putting undue strain on interdependent commercial networks.6 The global economy functions as a cohesive unit made up of individual gears and mechanisms that allow the greater machine to operate effectively. The consequences of throwing a wrench into this finely tuned machine cannot be overstated.
It is within this general understanding of a globalized trade system that we must explore the significance of trade interdiction.
Destruction and Seizure of Property at Sea: Mahan
As early as 1898, Mahan writings showed evidence of his serious thinking about international economics as the heart of sea power. There are hints he began thinking in this direction even earlier. Writing to The New York Times in November of that year, Mahan observed that in the global economy, “the exchange of goods, commerce, is the financial life of a nation,” or, put another way, “money is the sinews of war.”7 A product “embarked in the process of transportation and exchange, which we call commerce, is like money in circulation. It is the life-blood of national prosperity.”8 It thus followed, he said, that preventing the flow of goods forces private property to a standstill. “It the unproductive money in a stocking, hid in a closet,” or money hidden under the mattress, if you will.9 Capturing or interdicting trade on the commons is “made contingent upon movement; otherwise the property is merely bidden to stay at home, where it will be safe.”10 To understand how to apply sea power effectively, it is essential to understand the system on which one is trying to apply pressure, i.e., the international economy.
By 1907, Mahan recognized that the effect of interdicting commerce at sea would be felt much deeper in the enemy’s economic system than just the owners of the ships captured. He understood the complexity of the model—that interdicting a single ship would have multiple-order consequences. This point is critical. All merchants are affected, he recognized, and the “loss of one is the loss of all.” Maritime capture is felt by “the producer, the transporter, the handler, the broker, the merchant, [and] the banker no one of whom may be the owner of the particular property seized.”11 Preventing the flow of trade affects
the butchers, the bakers, the tailors, shoemakers, grocers, whose customers economize; the men who drive drays to and from shipping, and find their occupation gone; the railroads, as the great common carriers, whose freights fall off; the stockholders whose dividends shrink; we shall by no means have exhausted the far-reaching influence of this intermeddling with transportation. It is a belligerent measure which touches every member of the hostile community, and, by thus distributing the evils of war.12
The seizure of property on the commons is an attack on an enemy’s national life. Commerce interdiction serves no other purpose than to prevent circulation of wealth, or national life, “by stopping the transportation of his goods.” Ships carry significantly more goods than land transportation, so “the stoppage of a coasting trade [and] the closing of a few principal ports, would so congest the trunk lines of a national system that the influence would be felt instantly in every shop and household.” Successful commerce interdiction paralyzes the system, the effects are “thrown upon ports and roads which have not the necessary facilities,” and ultimately deranges an enemy’s economy.13 This is a remarkably “un-Mahanian” sophisticated analysis, when compared with what is commonly understood of Mahan.
Destruction and Seizure of Property at Sea: Corbett
Similar to Mahan, trade interdiction is central to Corbett’s conception of maritime strategy. The idea he is best known for is that “command of the sea means nothing but the control of maritime communications, whether for commercial or military purposes.”14 In his own words, the sea is “a means of communication between States and parts of States, and the use and enjoyment of these communications is the actual life of a nation at sea.”15
Corbett argues that in time of war, “by denying an enemy this means of passage we check the movement of his national life at sea in the same kind of way that we check it on land by occupying his territory . . . but no further.” What Corbett is saying, therefore, is that preventing an adversary from using the sea checks “the vitality of that life ashore so far as the one is dependent on the other.”16 Following this logic, the stoppage of maritime commerce succeeds so long as inland trade depends on sea trade. Otherwise, stopping maritime commerce is futile. Corbett’s view of land and sea commerce as separate systems is a critical point.
Fundamentally, Corbett treats “war at sea” as subordinate to “war on land.” In fact, he suggests that “no form of war indeed causes so little human suffering as the capture of property at sea.” He contends that commerce interdiction can only “deprive him of all the sea can give him, and produce the state of stagnation of his maritime life that conquest of territory does of his life ashore.” Corbett thus believed that while maritime interdiction is important, it is only supplementary to conquest on land. Put more simply, what happens at sea is incidental to what happens on land. In his own words, denying communications at sea “is but a trifle compared to what is gained ashore.” Again, the “capture of property on the high seas has an almost negligible military value,” and “blockade alone even if blockade in the old sense were still possible will not do.” For Corbett, control can only be obtained physically, either by capturing goods at sea or by conquest of territory. In doing so, one is “allowed to produce that stagnation of the enemy’s life at sea which an army is permitted to produce ashore by conquest of territory.”17
Careful reading of Corbett’s texts reveals he thought of economic activity in the simplest terms, employing an economic model more applicable to the 18th than the 20th century. Corbett did not conceptualize international commerce as a network, but as a point-to-point system. He believed physical conquest determined victory. Control of the sea was subsidiary. Physical command alone would bring an enemy to capitulation. Nothing more.
Corbett’s individualizing land and sea commerce, however, undermines the interdependency of a globalized system. He was unwilling or unable to comprehend the complexity of the network. Nor did he recognize the magnitude of the impact that interdicting trade at sea would have on a nation’s economy. There is no evidence in Corbett’s writings that he reflected on the significance of the international trading system, which today we call globalization. In fact, Corbett was so uncomfortable and unable to discuss the complexity of the international trade system that he relied on Mahan’s words!18
A close reading of Mahan’s and Corbett’s 1907 articles reveals that both agreed that the capture of private property and commerce warfare were fundamental to attaining victory. But there were key differences. Mahan went to great lengths to comprehend the economic world as it was in the early 20th century. He tried to understand how it was pieced together. He saw, for instance, that the global economy functioned interdependently, so disrupting the flow of one commodity in one part of the system could have knock-on effects throughout the entire system—prices go up and revenue down, supplies of goods become insufficient, and those aspects that regularly economize will be inhibited. Mahan contended that sea power used to interdict sea commerce could effectively disrupt an enemy’s national economy so significantly as to compel them to sue for peace. Corbett, by contrast, employed a simplistic model based on his historical studies of the 1700s.
Whereas Corbett regarded the maritime domain as subordinate to land, Mahan saw far greater possibilities for applying sea power as a tool for war. As sea power functions to maintain sea communications, then comprehending the mechanisms of the global trading system is crucial. Most important, the globalized economy is dynamic; inland trade and sea trade are fundamentally interdependent. Therefore, disrupting sea lines of communication forces trade onto other routes that do not normally bear that weight, disrupting the enemy’s entire commercial system. Mahan saw that in a globalized world, commerce interdiction is part of “a great and important wheel in a complicated machinery of interchange. If this is so, impairment of it must materially derange the whole, to the detriment of the nation.”19 Sea commerce interdiction is more than simply stopping maritime trade, it is an attack on national and global life itself.
Dust Off Mahan, Not Corbett
Mahan is lauded as the author of The Influence of Sea Power upon History: 1660–1783, which appeared in 1890. However, he continued to write for another 20 years, refining his ideas on the application of sea power. Because of their complexity, “the reasoned substance of Mahan’s work [has been] overlooked” or misunderstood.20 In truth, Mahan’s work cannot be used as a guide for commerce interdiction today, because so much has changed since he wrote. His theories cannot solve the problems of today, but they can serve as a guide for asking the right questions. His willingness to identify, define, and approach the problems inherent in employing sea power provides a model for inspiration—to educate officers on the nature of the global economy, and that the devil is in the details.
Interdicting Chinese commercial interests certainly seems a better plan than fleet-on-fleet action, especially as China layers its defenses in the South China Sea.21 However, approximately a third of global trade by volume transits the South China Sea.22 Simply asserting that Navy ships could “occupy shipping lanes and chokepoints to control commercial traffic,” and “stop, disrupt, and, if necessary, attack Chinese merchant shipping” without considering the significance and consequences of interdicting commerce—neutral shipping especially—indicates a misunderstanding of the true mechanisms of sea power. Leveraging sea power effectively is contingent on understanding how trade interdiction will have multiple-order consequences not only on China’s economy, but also on the entire global trading system.
But Corbett made no attempt to grapple with the globalized economic system. He had no clue where the “pressure points” lay, so his dicta could not be right—unless by accident. While Corbett’s simplicity is attractive, its utility for today’s Navy is questionable. The trade interdiction mission is complex. Corbett’s apparent discomfort with and inability to express the economic significance of commerce interdiction only amplifies his questionable relevance in maritime strategy. Yet, his views inform current U.S. Navy discussions regarding naval strategy and doctrine.23 All other things being equal, the enemy’s economy should be “the ultimate target of sea power.”24 Rather than relying on Corbett’s operational theory, perhaps the Navy should put strategy first, as Mahan did. If interdicting Chinese commerce is the plan, then it is time to dust off Mahan, not Corbett.
1. Daniel E. Ward, “Going to War with China? Dust Off Corbett!” U.S. Naval Institute Proceedings 146, no. 1 (January 2020).
2. Kevin O’Rourke and Jeffrey Williamson, eds., Globalization and History: The Evolution of a Nineteenth-Century Atlantic Economy (Cambridge, MA: MIT Press, 1999).
3. Nicholas A. Lambert, “Brits-Krieg: The Strategy of Economic Warfare,” in Understanding Cyber Conflict: Fourteen Analogies, George Perkovich and Ariel E. Levitte, eds. (Washington, DC: Georgetown University Press, 2017), 123–45.
4. Lambert, “Brits-Krieg,” 127.
5. Katherine C. Epstein, “The Conundrum of American Power in the Age of World War I,” Modern American History (2019): 2, 345–65.
6. Ivan Bloch, Is War Now Impossible? Being an Abridgment of “The War of the Future in its Technical, Economic, and Political Relations” (London: Ballantyne Press, 1899), vii–lxii.
7. Alfred Thayer Mahan, “Commerce and War,” The New York Times, 17 November 1898; Alfred Thayer Mahan, “Commerce and War,” The New York Times, 23 November 1898.
8. Julian Corbett, “The Capture of Private Property at Sea,” in Some Neglected Aspects of War, Alfred Thayer Mahan, ed. (Boston, MA: Little, Brown, and Company, 1907), 131. Corbett citing a quote from Alfred Thayer Mahan’s “Sea Power in Its Relations to the War of 1812.”
9. Corbett, “The Capture of Private Property at Sea.”
10. Corbett; Alfred Thayer Mahan, “The Hague Convention of 1907, and the Question of Immunity for Belligerent Merchant Shipping,” in Some Neglected Aspects of War, Alfred Thayer Mahan, ed. (Boston, MA: Little, Brown, and Company, 1907), 171.
11. Mahan, “The Hague Convention of 1907.”
12. Mahan, 163, 173.
13. Mahan, 165, 179, 189.
14. Julian Corbett, ed., Some Principles of Maritime Strategy (New York: Longmans, Green, and Co., 1918), 94.
15. Corbett, “The Capture of Private Property at Sea,” 131.
16. Corbett, 93, 95.
17. Corbett, 131, 132, 135–36.
18. See footnotes eight and nine.
19. Mahan, “The Hague Convention of 1907,” 178.
20. Jon Tetsuro Sumida, Inventing Grand Strategy and Teaching Command: The Classic Works of Alfred Thayer Mahan Reconsidered (Washington, DC: The Woodrow Wilson Center Press, 1997).
21. Ward, “Going to War With China? Dust Off Corbett!”
22. “Review of Maritime Transport,” United Nations Report (2016), unctad.org/en/PublicationsLibrary/rmt2016_en.pdf.
23. Nicholas Lambert, “False Prophet?: The Maritime Theory of Julian Corbett and Professional Military Education,” The Journal of Military History 77 (July 2013): 1055–78.
24. Lambert, “False Prophet?”