Changes in the global distribution of power and the locus of strategic competition shift the way nations think about naval power. At the turn of the twentieth century, Britain’s naval dominance came under stress, thanks to the appearance of Imperial Germany first as a competitor and then as Britain’s opponent in the First World War. As the relationship between Britain and Germany shifted from competition to war, Julian S. Corbett emerged as a key historian and strategic thinker—one whose writings sought to provide British leaders with a more complete understanding of what their dominant navy could accomplish in a changing international environment.
Though Corbett wrote for Britain, his writings contain lessons that are broadly applicable for understanding the choices available to dominant naval powers—a role the United States has occupied since the Second World War. The challenge for a state with a dominant navy is how to use its power at sea in combination with geographic advantages to obtain the greatest possible strategic effects. Indeed, Corbett’s theoretical arguments highlight many of the successes, challenges, and failures of the United States since 1945, and, applied thoughtfully, provide US decision-makers a clear view of the advantages, limitations, and mechanics of what a dominant navy can accomplish and why. His theories particularly emphasize that the land power of a state with such a dominant navy is only as strong as what can be projected and sustained at distance, and that naval dominance in combination with favorable geography gives states greater strategic choice about when and how to use force, and provides space for strategic recalibration that continental states struggle to achieve. Conversely, however, Corbett warns of danger maritime states face when they fail to capitalize on the advantages of isolation, and of particular challenges that naval dominance generates for coalition sustainment. Maritime states such as Corbett’s Britain or the United States since the Second World War improve their margins of success most when they capitalize on the advantages of geographic isolation, manage coalition partners well, and take advantages of opportunities for strategic recalibration.
Using Theory and History in Tandem
To a friend, Corbett admitted the challenge of applying theoretical and historical writings: “Your belief that the Service might have learnt a little more from my books is a comfort to me. I seem to have written so entirely in vain & seldom see any effect except where someone has mistaken or misapplied the teachings & consequently gone wrong.”1 Corbett’s lament provides caution when using his theories in conjunction with historical evidence from the history of the United States since 1945 to extract valuable lessons for contemporary strategy.
Theory is not infallible—whether it is Carl von Clausewitz, Sun Tzu, or Corbett. Rather, theory forces those applying it to ask questions while distilling wisdom from the past. Theory stimulates reflection, thinking, imagination, and creativity; it looks to the present and peers into the future to provide tools that assist decision-makers. At its simplest, making use of theory allows for a better understanding of cause and effect. These are the clearly imagined reasons why events may occur and the possible results that leaders can hope to achieve. Theory provides decision-makers with tools to forecast more analytically and effectively.
Corbett provided these tools to British decision-makers in the early twentieth century, but he claimed that it was up to them to decide how to apply them. According to Corbett, theory should not advocate. Just a few years before the outbreak of the First World War, he explained, “The theory of strategy . . . merely places the advantages of each before us & leaves the solution of each practical problem to practical men, as it occurs. It offers no solution, but only the means of arriving at a solution.”2 Theory does not provide “a substitute for judgment and experience.” Corbett reasoned, “Individual thought and common-sense will remain the masters and remain the guides to point the general direction when the mass of facts begins to grow bewildering.”3
Corbett’s theories remain extremely valuable for understanding US actions since the Second World War, and decision-makers should be aware of his theories.
Corbett’s theories remain extremely valuable for understanding US actions since the Second World War, and decision-makers should be aware of his theories. At the same time, his frameworks must, like all theories, be used judiciously. Some of his arguments are more valuable in the present environment than others. Thus, understanding context is an essential part of interpreting his theory.4 US history since the Second World War serves such a valuable purpose in this article; it provides a means of extending Corbett’s theoretical arguments to allow for a better understanding of which among his theories apply most effectively in the contemporary environment.
This context is where illustration, often in the form of historical examples, adds to the usefulness of theory. Without examples, theory often remains abstract—a series of cliches, catchphrases, and definitions that have no reality in themselves. Theory coupled with illustration, however, creates stronger conditions for serious and thoughtful analysis because historical examples provide a means to express theory’s value and validity. Consider what Clausewitz, the Prussian general and military theorist, asserted: “Theoretical results must have been derived from military history or at least checked against it.” He then maintained, “A great advantage offered by this method is that theory will have to remain realistic. It cannot allow itself to get lost in futile speculation, hairsplitting, and flights of fancy.”5
History provides multiple, real-world examples for contemporary leaders. To this end, Corbett followed an inductive approach “by which we argue from the particular to the general and from a mass of ascertained facts endeavour to construct a generalisation which will cover them all.” He advocated, “Collect and study the ascertained facts of war history, patiently build up your doctrine on the solid foundations they afford.”6 Elsewhere, he provided additional guidance on how historical examples informed theoretical arguments. People should use history “to find out where they are wrong; or, as it has been well said, they go to history to search for principles, not to prove those which they believe they have already found.”7 This approach is not easy, however. It requires the hard work of learning the historical context and then basing the theoretical foundations on that.
Corbett followed this inductive methodology by studying a wide array of historical cases from the age of the Spanish Armada through the Napoleonic Wars. He even wrote a two-volume study on the Russo-Japanese War, which took place from 1904 to 1905. Before his death in 1922, he completed the first three volumes of the official history of naval operations in the First World War, taking its history through the Battle of Jutland.8
Corbett applied history in such a way to provide British leaders with tools to more fully understand their contemporary environment.9 He understood that history and theory work synergistically. Both provide a means of “fertilising” the mind to amplify a leader’s judgment.10 History makes theory more relatable and more accurate, while theory makes history more useful by providing frameworks to more effectively apply historical understanding to the contemporary environment. Viewed through the lens of history, the principles Corbett identified come more fully into focus.
The link between Corbett’s theoretical arguments and the United States in the aftermath of the Second World War is not perfect. Differences begin with perspective: Corbett wrote explicitly for Britain in the early twentieth century. Small, especially in comparison to the United States, the British Isles by Corbett’s lifetime depended on trade for not merely wealth, but also the very resources the state and its people needed to survive. Over the centuries, British leaders used global trade and the financial power that resulted from that commerce to punch well above its weight. This allowed Britain to compete in both peace and war with continental powers that possessed greater size, populations, and even wealth.11
The United States in the aftermath of 1945 was different. Whereas engagement with the sea was a necessity for Britain, it has always been more of a choice for the United States, whose size and resources make it more a continental island. In the aftermath of the Second World War, US leaders chose to engage ever more fully with the world. This decision has made Corbett’s theories more relevant to the United States, but his theories cannot be applied wholesale.
Corbett’s Britain and the United States since 1945 possess similar geographical characteristics and a dominant navy, and both engaged extensively overseas—but did so differently. As a result, the comparative applicability of Corbett’s theory resides not in wholesale comparison, but in the mechanics of what a state with a dominant navy can accomplish and why.
The Advantages of Maritime Geography
Geography serves as a fundamental concept for understanding how states compete in the international environment.12 Location can bequeath opportunity or constrain choice. Maritime states including Corbett’s Britain and the United States since 1945 possess similar geographic characteristics that provide advantages for aiding in the defense of their respective homelands.
Corbett wrote for an island nation that had the advantage of a watery moat separating it from its European great power rivals. The English Channel kept opponents at bay—any invasion had to cross the water. Since Corbett’s day, air power, missiles, and even cyber threats have created fissures in the moat, but that fact remains: The channel provides significant protection from what Corbett labeled “an unlimited counterstroke.”13
The United States has benefitted from geography in even greater ways. Britain’s location at the periphery of Europe meant that its moat was narrow—on a good day, the European continent is visible from British shores. The United States, however, is in size a continental island, replete with resources, with comparatively weak northern and southern neighbors and immense oceans to its east and west. It therefore possesses a broader range of choices. Moreover, geography has insulated the United States from all but the most catastrophic unlimited counterstroke. This has caused opponents to resort to disruptive and often unconventional actions, including terrorist events such as the September 11th attacks as well as modern cyber threats.
Contrast the maritime geographies of Britain and the United States with the continental geographies of states like Germany and Russia.14 Continental states have land links with powerful rivals, and are vulnerable to an unlimited counterstroke by direct invasion across these borders. This situation has traditionally required prioritization of the army over the navy. Without a powerful army, the territories of a continental state are at risk; the capital is vulnerable; and even survival may be in jeopardy. Consider the Eastern Front of the Second World War fought between Nazi Germany and the Soviet Union. These two continental powers savagely struggled for survival in a way that was only possible because geography allowed it. Russia’s 2022 invasion of Ukraine provides a contemporary example. Long shared land borders have largely defined the course of military operations and provided Russia with the means to pursue its political objectives. In comparison, maritime states are sheltered by water from the immediate threat of conventional land warfare, giving them the advantage of isolation in homeland defense.
Command of the Sea
Dominant navies enhance the defensive benefits of geography for maritime states and allow them to thrive through engagement with the world. Engagement makes them relevant, builds wealth, and secures resources. To reach across the water at acceptable risk, maritime states must possess a navy capable of commanding the sea in times of war. Command of the sea serves as a critical link between Corbett’s Britain and the post-1945 United States.
While some navies focus on good order at sea, others on coastal defense, still more on protecting maritime commercial interests, a very few navies can not only do all of those missions but can also possess the capability to defeat any naval rival and project significant power to distant regions.15 By possessing these capabilities a dominant navy can exercise what Corbett labeled “command of the sea,” which he defined as “establishing ourselves in such a position that we can control the maritime communications of all parties concerned.”16
Obtaining and using command of the sea, however, are only possible during conflict, because command requires the wholesale regulation of maritime activities.
Possessing command of the sea can lead to significant strategic effects. Obtaining and using command of the sea, however, are only possible during conflict, because command requires the wholesale regulation of maritime activities. Historically, the sea’s principal value has been that of a highway linking land masses; trade routes and the commerce that passes along these maritime arteries are therefore the great prize in naval warfare.17 The state that commands the sea can use these critical sea lanes for itself while denying them to opponents. Moreover, the state that possesses command of the sea will regulate the activities of neutral parties. As a result, Corbett aptly cautioned, “It may be taken as a law of maritime warfare, which cannot be omitted from strategical calculation with impunity, that every step towards gaining command of the sea tends to turn neutral sea powers into enemies.”18 For this reason, command cannot be sought in peacetime. This consideration has become increasingly important since 1945, given the proliferation of maritime commercial activities and the diverse ways that humans exploit the sea.
Navies take a long time to build and are costly to keep operational.19 Corbett wrote in a period in which naval power was defined in terms of warships, but the instruments that affect operations at sea today have expanded dramatically to include aerial platforms, missiles, drones, and space-based systems. To sustain the instruments of naval power over the long term requires consistent resourcing, which is only possible with a favorable political culture. While the political culture of Corbett’s Britain differed from that of the United States since 1945, political leaders and the population in both countries have devoted significant national resources to developing and sustaining their navies so that in times of conflict they possess the ability to command the sea.
A critical question for a state possessing the dominant navy entails whether it can command the sea when the situation demands. When necessary, the dominant navy with a latent ability to command the sea must be able to accomplish two objectives. First, it must be capable of defeating maritime challengers to secure command of the sea; and second, it must be capable of controlling maritime communications in order to exercise command.20
Securing command of the sea requires the removal of challengers, usually through such actions as battle or blockade. During Corbett’s time, rising challengers in Europe, Asia, and across the Atlantic worked to upset Britain’s naval dominance, calling into question its ability to secure command.21 Since the Second World War, the United States has possessed that ability in most regions, but in the present environment rising naval powers in Asia—in particular China—are eroding that ability.22
Securing command of the sea, Corbett warns, is “only a means to an end. It never has been, and never can be, the end itself.”23 Rather, it allows the state to use the sea to “exercise command.” He explained, “I must confess that I have always thought one of my best bits of work was to formulate the distinction between holding the command & exercising it. It seems to me to go to the root of the whole thing.”24 He elaborated, “We engage in exercising command whenever we conduct operations which are directed not against the enemy’s battle-fleet, but to using sea communications for our own purposes, or to interfering with the enemy’s use of them.”25
Exercising command involves protecting friendly activities at sea and preventing activities that can support the maritime state’s opponents. Protecting and preventing commercial activities work in tandem because, as Corbett explained, “At sea the communications are, for the most part, common to both belligerents. . . . We as a rule cannot attack those of the enemy without defending our own.”26
Controlling maritime communications entails more than navies—it requires leveraging informational, legal, diplomatic, and financial levers of power. The more fully these levers are emplaced in peacetime, the more effective they can become during war. In the years before the First World War, Corbett sought to maintain legal frameworks that allowed for seizure of maritime commercial cargoes during conflict.27 Preparing these legal frameworks in peacetime gave Britain significant leverage in stifling Germany’s international trade once the First World War began.28
The navy plays an essential role in controlling maritime communications. Corbett maintained, “So soon as the mercantile marine became a recognised burden on the navy the main lines of commerce became also the main lines of naval strategy.”29 He cautioned, however: “By no conceivable means is it possible to give trade absolute protection. . . . To aim at a standard of naval strength or a strategical distribution which would make our trade absolutely invulnerable is to march to economic ruin.”30
Controlling maritime communications entails more than navies—it requires leveraging informational, legal, diplomatic, and financial levers of power.
Commerce protection can occur through either indirect or direct action. The overall naval balance provides indirect means—the more a state possesses latent command at sea, the more secure its trade routes are in peacetime.31 War, however, requires navies to devote warships directly to the defense of commerce. This necessity has historically entailed a combination of convoys and patrols.32 As the size and diversity of the commercial fleet in the late nineteenth and early twentieth centuries increased, Corbett speculated that a comprehensive convoy system would be too inefficient; he thus emphasized patrols in areas where commerce was most dense.33 Although this speculation proved inaccurate—with Britain needing to resort to an ever more comprehensive convoy system in the First World War to defend commercial traffic against German submarine warfare—he was correct to note the important relationship between commercial and naval power.
Furthermore, Corbett correctly deduced that command of the sea does not mean complete insulation from injury.34 Ships will be lost and regions contested. Littoral waters pose particular challenges to command, and require significant power projection, large numbers of platforms, and high levels of risk tolerance. The development of mines and flotilla—including torpedo boats and submarines—made the littorals an increasingly dangerous place during Corbett’s lifetime.35 This danger has increased since 1945 as technological developments in surveillance, mines, submarines, air power, drones, and especially missiles have expanded the littoral space.
Some might claim that command of the sea is no longer possible. Other instruments of power will make attempts to command the sea prohibitively dangerous. Moreover, the ever-expanding volume of commerce and the increasingly diverse ways that humans exploit the maritime environment will limit even a dominant navy’s ability to successfully exercise command. Events during the First World War demonstrated that while the direct control of maritime communication rested with the British navy, effective command increasingly required the integration of informational, legal, governmental, financial, and commercial elements. Furthermore, technological developments affected command of the sea—smaller warships attained battle power through the use of torpedoes, giving them the ability to sink even the largest warships.36 As Corbett witnessed Germany’s use of submarines, he concluded that exercising command of the sea “can’t be done so cleanly as of old.”37
Despite these developments, the nature of international competition is likely to continue to push leaders to attempt to obtain something akin to command of the sea in wartime. Since 1945, the United States has not faced constraints on command as difficult as Britain’s during the First World War. The outcome of the Second World War left the United States with a highly favorable naval balance. This balance has been sustained since 1945 through resourcing a fleet more capable than potential competitors as well as leading the world in integrating the US Navy with other instruments of national power. The erosion of US naval power in the contemporary environment, especially in Asia, however, has begun to call into question America’s latent ability to command the sea.
Employing naval power with the objective of influencing events ashore, for example, reflects the fact that warships cannot occupy land or march on an opponent’s capital.
To sustain America’s global position, it is essential that its latent ability to command does not entirely slip away, for this quality bequeaths tremendous benefits for the country that possesses it. First, in combination with geographic isolation, this ability provides a powerful tool to shield the homeland. Second, the ability to secure sea lanes allows for the safe flow of international maritime commerce and projection of power overseas—ultimately creating the confidence necessary to sustain and grow a maritime commercial system and serve as the foundation of power projection and global engagement.
Crossing Domains and Limited War
Obtaining or even exercising command of the sea does not generally secure political objectives overseas on its own. Writing about the late Elizabethan Age, Corbett identified “the limitation of maritime power” and claimed, “It was not seen that there is a point beyond which hostilities by naval action alone cannot advance.”38 His broader historical studies led him to conclude that wars have traditionally been fought over terrestrial objectives, be it the control of territory or who ruled a given area.39 As a result, the puzzle for a state with a dominant navy is how to cross domains in order to obtain strategic effects on land. Corbett’s solution came in two parts. The first entailed the integration of the navy as an enabler to work in combination with other instruments of power.40 A second way to compensate for the limitations of maritime power involved seeking limited political objectives.
Crossing domains is complicated, because cross-domain strategic effects tend to involve indirect pressure. Employing naval power with the objective of influencing events ashore, for example, reflects the fact that warships cannot occupy land or march on an opponent’s capital. Instead, leaders must find circuitous routes that are often complex in their design and involve multiple instruments of power. At the same time, the navy must maintain its more direct mission of influencing what occurs at sea, including protection of commerce. Understanding the challenge of crossing domains has become ever more important as new domains—including air, space, and some might even argue cyberspace—emerge to complicate the global environment.
Corbett’s second solution for mitigating the limitations of maritime power used Clausewitz’s theory as a point of departure. Whereas Clausewitz wrote for Prussia—a continental land power in central Europe with an army as its dominant instrument—Corbett grappled with how the British maritime state needed to use its navy along with other instruments to attain its political objectives. The difference in land versus maritime focus forced Corbett to adapt Clausewitz’s philosophy of war to create a strategic theory for Britain.41
To accomplish this, Corbett contrasted war for limited and unlimited political objectives,42 resulting in what some have claimed to be among his most important contributions to the theory of war.43 While unlimited objectives require enough leverage over an opponent to dictate terms, limited objectives are messier, seeking specific aims without pushing the opponent to the point of capitulation.44 A limited political objective leaves the opposing government in power and requires a negotiated settlement. Corbett asserted, “The distinction between the two kinds of war may appear academical, but it will be found, nevertheless, of the greatest assistance in arriving rapidly at a just appreciation of the situation and in detaching at once the main lines on which our war must be planned.”45
Corbett contended that maritime states are uniquely positioned to wage limited war. For example, Britain’s geography and dominant navy protected it from opponents seeking unlimited objectives by depriving them of the conventional means to obtain that end state. The combination of a watery moat and a dominant navy forces the maritime state’s opponents to conform to limited war.46
The value of the objectives pursued had to be balanced against the risk of nuclear escalation, which often led the United States to avoid crossing real or perceived redlines.
While maritime states have defensive advantages in limited war, options narrow when these states seek limited offensive objectives. A maritime state’s capabilities are strongest at sea, but war is almost always decided on land, and a maritime state’s land power is only as strong as what can be projected and sustained abroad. It is possible to partially mitigate this weakness through the recognition of the opponent’s geographic vulnerabilities and careful coordination among the maritime state’s instruments of power. Specifically, Corbett asserted that leaders of maritime states can obtain disproportionate effects by having their navy put their army ashore at a time and place where maximum strategic advantage can be achieved.47 Additional mitigation can be attained through limited political objectives that Corbett believed were better matched to Britain’s means.48
A combination of factors—including nuclear weapons, superpower rivalry, and international organizations—have driven the United States to fight for limited political objectives since 1945. Yet this fight has resulted in particularly difficult conundrums for American leaders and citizens, who have been more at home with the clarity of unlimited war—perhaps as a holdover from the Second World War’s demand for “unconditional surrender.” This line of thinking can also be explained by the fact that the United States is capable of more by virtue of its continental size. Limited political objectives in places like Korea in the early 1950s and Kuwait in the early 1990s—when opposing regimes remained in power and objectives were only partially achieved—have tended to ring hollow to both the American citizenry and leadership.49
Even with size, population, and wealth, nuclear weapons and the international environment have propelled US leaders to consider limited objectives, which allow them to seek some outcomes while reducing the risks of escalation and maintaining its global position. Limited objectives, however, do not provide every desired result, and make the costs they impose in terms of both blood and treasure harder to explain.
Nuclear Weapons and Corbett’s Theory
When Corbett wrote at the turn of the twentieth century, he focused on the naval component, and how to integrate it with land, diplomatic, economic, and financial power. Since his lifetime, however, instruments have emerged that add new dimensions to strategic decision-making.
Nuclear weapons are especially significant. Water, in combination with naval power, shields maritime states from the conventional unlimited counterstroke, but nuclear weapons provide the opportunity to negate this defensive shield. This situation provides a powerful incentive for the maritime state’s opponents to obtain nuclear weapons or a nuclear ally.
Beginning in the 1950s, the United States engaged in competitions with nuclear-armed states. Decisions became far more dangerous if an opposing state possessed nuclear weapons due to the risk of escalation to the level of a nuclear exchange. The Cuban Missile Crisis in October 1962 pinpoints how cautious US leaders needed to be, even though the “quarantine” of Cuba clearly indicated that the US Navy possessed command of the sea.
The value of the objectives pursued had to be balanced against the risk of nuclear escalation, which often led the United States to avoid crossing real or perceived redlines. Limited political objectives were one way to make this possible, and the United States repeatedly sought such objectives against states like the Soviet Union, China, and their proxies. For example, the United States sought its objectives in South Vietnam while limiting its aims vis-à-vis North Vietnam and keeping objectives related to China and the Soviet Union more limited still.
Nuclear weapons have made Corbett’s theory simultaneously more and less viable. His theory is less practical because the maritime state’s homeland is no longer secure, due to the potential for a new type of unlimited counterstroke. Conversely, however, a nuclear unlimited counterstroke became increasingly unthinkable with the proliferation of nuclear weapons capabilities—meaning that when two sides in a conflict possess such weapons, Corbett’s theories became more relevant again. For example, in the Cuban Missile Crisis and the Vietnam War, US leaders had to carefully shape limited objectives involving the use of force at the right time, in the right place, and in the correct amount to obtain maximum strategic effects without triggering a nuclear exchange.
Though Corbett wrote before the advent of nuclear weapons, his historical studies leave us with powerful advice that transfers to the nuclear age. For example, he asserts, “The first and greatest advantage that a belligerent can obtain is the power of making the war what he wishes it to be, to make it, that is, limited or unlimited as it best suits his aims, position, and resources.”50 Nuclear weapons make this pronouncement even more relevant, because they make limited objectives the only thinkable option. Though limited war remains problematic for the United States, naval dominance and geography can help its leaders take advantage of this “first and greatest advantage.”
The Decision for War: Ends and Means
Maritime states with command of the sea have greater freedom of action when deciding to enter conflicts. The United States did not have to become involved in Korea in 1950, in Vietnam in the 1960s and early 1970s, in Kuwait in 1991, or in Iraq in 2003, just as Britain did not have to wage the Crimean War against Russia in the 1850s or join the First World War in 1914.
Leaders with this degree of choice can base their decisions for war on national interests that reach beyond national survival. In fact, their decisions go beyond a binary “yes” or “no,” by also containing significant latitude in “how.” But in engaging primarily in what become wars of intervention (of one kind or another), these states must consider what Clausewitz posited about not taking “the first step without considering the last.”51
As Corbett wrote in 1905, “So we discuss a sort of abstract plan of war, as if wars were all much the same—whatever their object & whatever the means at the disposal of the belligerents. But they are not so & until we know [the] ends of war & means, we can’t know what we are talking about.”52 His admonition remains relevant today: Not all wars are alike. Deciding whether and how to enter a conflict demands a thorough assessment of attainable ends and available means—a principle that applies not only to one’s own state, but to opponents, partners, and even neutrals.
For the maritime state, naval dominance has too often produced a focus on available means rather than desired ends. Britain during Corbett’s lifetime and the United States since the Second World War have possessed substantial means of projecting forces to distant regions. At times, however, the capability to project forces overseas has blinded leaders from asking difficult but important questions about whether the objectives are truly attainable, and at what cost.
Corbett lamented the thought process of British leaders when they intervened in the First World War. Since the Royal Navy was capable of securing command of the English Channel, British leaders perceived that there was little risk in getting the British Expeditionary Force to the continent immediately following the outbreak of hostilities. Once across the channel, the army quickly became drawn into the fighting in Belgium and France. Additional forces followed until Britain ended up fighting the war as a continental land power, which resulted in sacrificing its maritime advantages. In the middle of the war, Corbett described the resulting attritional, continental struggle fought by the British army on the Western Front as “a costly method of war, beating the Germans at their own game.”53 Corbett recognized that Germany, as a continental power, was fighting massive land campaigns on its eastern and western fronts, but believed Britain, as a maritime power, did not need to fight this type of war. Forsaking Britain’s key advantages as a maritime state bled out its people and finances. As Corbett wrote, “I wept when our whole Expeditionary Force was going to France, and felt what it would mean.”54
US leaders have possessed the naval and economic dominance to skirt Corbett’s warnings since 1945.55 American leaders have not faced the question of whether they could project and sustain forces to places such as Korea, Vietnam, or the Middle East. As a result, decisions for war since 1945—whether supporting partners, intervening in ongoing conflict, or acting preemptively—have often occurred without sufficient focus on objectives, their costs, and their feasibility. Unless the attainability of the desired ends and the costs of the intervention are in alignment, broader global objectives are likely to suffer.
Is the comparison between Britain’s decision in a world war and these US decisions since 1945 unfair, given the difference in their magnitude? Regardless of the scale of conflict, the thought process should be the same. Questions of attainable ends and their value must be assessed in relation to projected cost. Available means should become more of a prerequisite rather than the determinative factor.
While Corbett’s Britain was weaker and the magnitude of US involvement smaller, the mistakes have paralleled each other: Leaders have focused too much on means, and not enough on attainable ends and their costs. While potentially unsurprising, given the tremendous amount that both Corbett’s Britain and the United States have paid to generate and maintain their naval and expeditionary capabilities, this focus remains strategically unwise. Having the means to become involved in a war does not necessarily signify that a state should do so, or do so in the easiest way. Hard thinking is required to make the greatest use of the costly instruments developed in peacetime.
The Challenge of Overseas Operations
Corbett labeled actions ranging from naval bombardment to deploying troops overseas “direct territorial attacks.”56 The effects they can achieve, however, are imperfect, in large part because the power of maritime states dissipates quickly when engaging with opponents ashore.57 Leaders of maritime states often fail to understand this important point because they tend to overestimate the attainable ends from direct territorial attacks and underestimate their costs.
Bombardment has the advantage of unity of effort. Because a navy can conduct bombardment without recourse to other services, coordination is easier. During Corbett’s day, bombardment entailed the use of ships to directly engage targets ashore, but the range of their guns was limited. As a result, warships had to approach close to the shoreline, and even then the targets needed to be in close proximity to the coast. Risks for the ships involved remained high. The British met with failure when they tried to push their way through the Dardanelles with ships on March 18, 1915, as shore batteries and mines inflicted high losses but had few effects.58
In the Second World War, the United States used the juggernaut of its technological and industrial resources to overcome some of the difficulties with bombardment, and carried these advantages into the postwar world. Aircraft, missiles, and more recently, drones have provided a standoff capability to more effectively identify and engage targets at greater distances than in Corbett’s day. Since 1991, for example, Tomahawk cruise missiles have been go-to US instruments for direct territorial attack, targeting locations ashore including in Iraq, the former Yugoslavia, Somalia, Afghanistan, Yemen, Libya, and Syria.59 The advantages of pinpoint accuracy, and of keeping US personnel away from risk, promise great advantages—but these attacks have often failed to yield definitive results. Command of the sea coupled with technologies—including air power and precision strike—have led US decision-makers to believe that they can mitigate many of the difficulties of attaining strategic effects from bombardment. This viewpoint, however, increases the confusion of means with attainable ends.
Deploying troops overseas is a form of direct territorial attack more likely to yield strategic effects. Corbett saw this as the particular form of war “which was the most decisive form of offence within our means.”60 This approach, however, does increase cost and risk. The potential for casualties increases, as does the potential to get drawn deeper into conflicts because the state’s blood, treasure, and credibility have been more directly put at stake.
Both British and American leaders have had to grapple with these limits of expeditionary warfare. Corbett witnessed Britain using this method in the First World War, and studied numerous other historical examples. Since 1945, the United States has also resorted to putting personnel ashore in distant lands. Such operations are expensive to sustain; mobility becomes problematic when forces transition from water to land; and getting soldiers into a theater tends to be time-consuming. Even with uncontested sea lines of communication, the United States took years to build up forces in South Vietnam in the mid-1960s and approximately six months in Saudi Arabia prior to the Gulf War of 1991.
Moreover, truly integrated joint operations are difficult because multiple instruments of power must work together, each sacrificing some independence for the overall objective. An easier way involves engaging in parallel lines of effort with each instrument doing what it does best—but in such circumstances, involvement follows individual stovepipes as each component acts along its preferred line of effort, often sacrificing the advantages from joint or even interagency cooperation as a result.
The Dardanelles in 1915 provided British leaders with an opportunity to reinvigorate a joint approach in the First World War after its forces had become stalemated on the Western Front in France and Belgium. The operation failed, however. Corbett believed British leaders had forgotten the synergistic effects that could be obtained from naval and land power working in combination, asserting, “It meant, moreover, entirely ignoring the fleet and its oft-proved capacity for substantially increasing the power of the army.” He lamented, “It was impossible not to protest.”61 Britain had developed the world’s leading navy, yet Corbett believed that the way it intervened in 1914 and afterward squandered this advantage as the army and navy fought parallel but separate wars.
Isolation is one of the most critical strategic advantages a maritime power can exploit.
Corbett had foreseen this possibility a decade earlier. At that time, he revealed to a friend, “All our mistakes are due to neglecting to treat Naval and Military Strategy as one.”62 Seven years later and three years before the outbreak of the First World War, he warned: “We are accustomed, partly for convenience and partly from lack of a scientific habit of thought, to speak of naval strategy and military strategy as though they were distinct branches of knowledge which had no common ground. It is the theory of war which brings out their intimate relation. It reveals that embracing them both is a larger strategy which regards the fleet and army as one weapon.”63 Even so, Corbett found that the effectiveness of attacks from the sea dissipate when crossing onto land. Several methods allow for maritime states to expand their narrow margins of success. These methods include the advantages of isolation, the effective management of coalition partners, and the opportunities for strategic recalibration.
Expanding the Margin for Success: Isolation
Corbett determined that isolation provides the maritime state with some of its greatest advantages. Isolation can be applied against the objective or against the opponent. Isolating the objective tends to be geographic and requires the use of naval power, while isolating the opponent tends to place more reliance on partner states in combination with geography and naval power.
Isolation of the objective can prove advantageous in both limited and unlimited wars. In limited war, one does not fight an opponent until it can no longer resist; instead, limited war seeks specific objectives. If these objectives can be isolated, they are easier to secure during the war and retain at its end. In cases of unlimited war, objectives that can be isolated tend to be intermediate in character. These objectives weaken the opponent and serve as stepping stones on the path to final victory.
The most obvious and effective form of isolation occurs when navies can physically isolate objectives ashore. Corbett contended that isolation gave the maritime state’s relatively small land force the ability to punch well above its weight because it restricted the size of the opposing force it needed to defeat on land.64 Total isolation of the objective is most possible when the maritime state can use its navy to encircle an island where the opponent is positioned. Think of battles such as Okinawa and Iwo Jima in the Second World War, in which the Japanese could not reinforce their beleaguered garrisons. These islands could thus be secured as bases on the way to Japan.
Isolation proves much more difficult when objectives are on large landmasses. Still, partial isolation is possible in peninsulas such as Iberia and Korea. Corbett recognized that Britain used the geography of Spain and Portugal to its advantage during the Napoleonic Wars, and that the mobility Britain obtained from naval dominance proved more effective than French reliance on land-based lines of communication.65 In the Korean War, the United States proved more successful as its Communist opponents advanced further down the Korean Peninsula, but also faced increasing challenges as US forces and their partners advanced toward the Chinese border.
Isolation is one of the most critical strategic advantages a maritime power can exploit. This only occurs, however, where objectives are geographically vulnerable to isolation, or if the opponent places itself in a position where the maritime state can sever lines of communication. Geography does not always provide these advantages, as Corbett witnessed during the First World War. Though Germany’s colonies in Africa and the Pacific could be geographically isolated and were vulnerable to seizure, these assets were not valuable enough to have a significant influence on the war’s outcome. In Europe—the main theater—Germany did not have important geographical regions that could be isolated. The Ottoman Empire was Germany’s most exposed ally, and was in fact physically isolated from Germany until Bulgaria joined the war in October 1915, but British leaders failed to find a theater against the Ottomans where isolation could quickly gain pivotal effects at acceptable cost.
Isolating opponents is more complicated because it relies on a combination of naval power and diplomacy. In the 1960s and early 1970s, the United States proved unable to isolate North Vietnam. As a result, the North received aid across its northern border with China. In addition, for much of the period, the North received assistance from China and the Soviet Union through its only major port, Haiphong. Finally, the North developed what became known as the Ho Chi Minh Trail through Laos and Cambodia to sustain its operations in the South.66 The failure to isolate North Vietnam limited what the United States could accomplish in South Vietnam. Since 2001, American strategy has also struggled with isolating transnational actors—both along the porous borders of Afghanistan and in other locales, especially when borders do not serve as effective barriers, water is not available to create isolation, and opponents operate in small groups, often without fixed territory of their own.
Note that when the Islamic State of Iraq and Syria (ISIS) created a physical caliphate based on a specific geographic area, including a capital and population centers, isolation again became possible. Here, however, it had less to do with geography and more to do with diplomacy and regional dynamics that could confine it to a specific area—an effort involving not just the United States but also the Arab League, NATO, the European Union, and the states of the Gulf Cooperation Council.67 Iran’s opposition to ISIS added to that isolation.
Thus, when diplomatic isolation has multiple layers—from immediate bordering areas, to the broader region, and beyond—diplomacy can create isolation in depth. Naval power through its influence over the sea lines of communication proves especially effective when seeking to achieve isolation in depth. During Corbett’s lifetime, diplomacy aided British efforts to isolate Germany in the First World War. The Triple Entente among Britain, France, and Russia, joined later by other states, sealed off the eastern, western, and eventually the southern borders of both Germany and its Austro-Hungarian ally. When the United States entered the war in 1917, isolation in depth became more effective because the most powerful neutral state had joined the coalition.
In the Gulf War, the United States isolated Iraq diplomatically by developing partnerships with several of Iraq’s neighbors and using the preexisting animosity between Iraq and Iran. In this case, isolation was not merely the product of a coalition of countries surrounding Iraq and Kuwait, but also included the dominant global naval power, the leverage of the United Nations, and an array of partners around the globe. Together, these partnerships built legitimacy, secured funding to sustain the coalition, and provided necessary bases and forces—again highlighting the importance of isolation in depth.
Both Corbett’s Britain and the United States since 1945 have used isolation to increase their margins for success. When isolating objectives, the state with a dominant navy can use water to create a barrier, which allows expeditionary land forces to engage only part of their opponent’s forces. The possibilities of geographic isolation are relatively constant, based on the relative location of water, land, and terrain features; by contrast, isolating opponents tends to be more situational. In addition to using naval dominance in combination with geographic advantages, isolating opponents can also benefit from how well the state with a dominant navy manages its formal alliances and more informal partnerships.
Expanding the Margin for Success: Coalition Partners
Though diplomacy can be a valuable tool for isolation, that is only one of several advantages possible through international engagement. Corbett identified diplomacy’s significance as follows: “To decide a question of grand strategy without consideration of its diplomatic aspect . . . is to decide on half the factors only.”68
In fact, Corbett contended that one of the three functions of the fleet in war is its ability to “support or obstruct diplomatic effort.”69 Thus, he reasoned, “It is evident that we require for the guidance of our naval policy and naval action something of wider vision than the current conception of naval strategy, something that will keep before our eyes not merely the enemy’s fleets or the great routes of commerce, or the command of the sea, but also the relations of naval policy and action to the whole area of diplomatic and military effort.”70 Using the navy to foster diplomatic engagement provides the maritime state with potentially powerful advantages.
Partners can give the maritime state basing at strategically important locations. This arrangement has allowed maritime states to project force into friendly locations that the maritime state’s opponents find disadvantageous. During the British intervention in Iberia in the Napoleonic Wars, Lisbon provided a secure base that could be sustained from the sea, allowing Wellington’s army not just to survive but to thrive.71
American allies have provided similar opportunities by hosting bases that maintain the advantages of forward presence. Located close to the theater of operations in Korea, Japan provided the United States with a secure base—geographically separate but within the range of air power. In the Gulf War of 1991, the United States used Saudi Arabia as a base and starting point for operations to repel the Iraqi invasion of Kuwait.72 Rather than supporting operations from the homeland, the United States could shorten its lines of communication to make it easier to sustain forces in the region.
This advantage, however, has limits. These limits appear especially when the US military seeks to operate in landlocked countries like Afghanistan.73 There, a combination of costly air lines of communication and long overland supply routes allowed the United States to maintain this theater, but at the cost of sacrificing its comparative maritime advantage.
Prioritization is essential to compete within a state’s means, and sharing burdens with allies can allow that. Corbett understood that Britain’s comparative advantages were economic, financial, and naval. Even with its economic and financial strength, however, Britain lacked the wealth to sustain a large navy and large army simultaneously. Catastrophe resulted when Britain attempted to field both a dominant navy and a continental-sized army in the First World War, which resulted in a high price in both blood and treasure as the war weakened Britain’s global financial position.74 Maritime powers often have tremendous wealth, but it is not inexhaustible.
Burden sharing poses particular challenges for dominant naval powers. Naval burdens are difficult to shift since the navy is the unique instrument of the maritime state. Risks also become higher if the maritime state shifts essential naval missions onto partners because this diminishes the dominant navy’s latent ability to command the sea, with all the benefits described above.
Land forces are more fungible, and tend to drain rather than build wealth. As a result, coalition partners are especially valuable when they provide land forces to augment those of the maritime state. In such cases, the maritime state seeks partners to do the work on land, providing strengths where the maritime state is weakest. During the Napoleonic Wars, for example, Britain successfully shifted the burden of fielding the large army essential for the defeat of Napoleon onto European coalition partners; Russia, Prussia, and later Austria in the last years of the struggle provided the massive armies necessary for victory. On a different scale, the United States has sought to develop local land forces in places such as South Korea, South Vietnam, Iraq, and Afghanistan. Not only has this arrangement fostered the potential for legitimacy by putting a local imprint on operations, it has also potentially provided a more cost-effective way for a maritime state to maximize its power and use its comparative advantages over the long term.
As with most possibilities, this situation has not proven an unfettered advantage. Local forces must be subsidized, especially in their formative phase, and they do not always prove effective. The leaders of maritime states need to make hard choices based on careful assessments about the viability of partner forces, or the maritime state’s money—followed by its legitimacy—will be thrown away.
Other significant barriers exist when a maritime state attempts to have allies work for it. Partners have their own objectives that do not always align with those of the dominant naval power. To a friend, Corbett related the brutal truth: “We have always had to spoil our hand . . . to keep allies in a good temper.”75 NATO provides a long-term example of the difficulties of the United States convincing its most important alliance to contribute to the burden of its own defense. The more the burden is shifted onto allies, the more they demand and the more independently they act. The less the burden is shifted, however, the more the dominant naval power pays and sacrifices its comparative advantages. This difficult balancing act is more complex because partnerships are often developed in distant regions; allies must believe the maritime state will uphold its end of the partnership, or long-term questions of maintenance work against burden-sharing.
Careful engagement with partners is necessary if the maritime state hopes to expand its margins of success. Partners provide numerous advantages ranging from aiding in isolation, to providing basing for forward presence, to compensating for the weaknesses of the state with a dominant navy, to increased legitimacy. A maritime state’s relationship with its coalition partners tends to function most effectively when leaders of the maritime state and their partners are able to link their objectives. Shared ends create legitimacy and can increase the willingness of both the state with the dominant navy and its partners to pay for those objectives in blood and treasure. Means, however, cannot be forgotten. These include the means that both the maritime state and its partners are able and willing to expend. If means are not balanced with the ends, partners will narrow the maritime state’s margin of success.
Expanding the Margin for Success: Reassessment
No matter how well leaders identify attainable ends, seek the assistance of partners, and recognize the possibilities of isolation, a level of risk always exists when employing force. This risk stems from the very nature of war, where complex interactions occur among competitors strategizing constantly about how to achieve their objectives in the face of resistance from others.76 A maritime state is especially effective at minimizing the risks of this kind of interaction, and can use reassessment in the aftermath of both success and failure to further widen its margins of success.
Careful engagement with partners is necessary if the maritime state hopes to expand its margins of success.
Reassessment for continental states tends to yield fewer choices. Building on Clausewitz’s theory, Corbett noted that wars among continental states tend to escalate toward the unlimited form because geography allows the side that can escalate to do so. Even the losing side in wars among continental states has the opportunity to expand objectives in a search for more meaningful outcomes.77
Maritime states have flexibility because their watery frontiers minimize the potential for escalation—opponents are unable to cross the water to invade.78 Moreover, the navy provides the capacity to move forces overseas, which allows for escalation on the maritime state’s terms by opening new theaters of operation and reinforcing those that already exist. This flexibility also allows maritime states to limit losses by more effectively closing theaters that are not providing desired results. Possessing this capability, however, comes with the tremendous responsibility of understanding oneself, one’s opponent, and other actors that can influence outcomes.
When geography and naval power shield the maritime state’s homeland, leaders and people can misperceive rewards and risk, and can also misidentify cost and feasibility. In the Seven Years’ and Napoleonic Wars, British leaders occasionally overreached, but avoided irreparable harm—a significant reason that Britain emerged on the winning side in both wars.79 This outcome is not easy, however. In a study of the Russo-Japanese war, Corbett identified how easy it can be for the people and leaders of a maritime state to overextend. Japanese leaders understood their narrow margin for success, but their people did not grasp Japan’s precarious position. Corbett claimed: “It was undoubtedly a peace cleverly snatched by the Japanese at the most favourable moment, but in Japan it was received with execration. The astute Plenipotentiaries were branded as traitors.”80 Because of the shrewd assessment by Japanese political leaders of their narrow margins of advantage, Japan eked out a victory. Even with success, the Russo-Japanese War demonstrates the difficulty of explaining the limitations of maritime power to populations who have paid costs in blood and treasure.
Political and military leaders of maritime states gain their greatest advantages when they understand the margins under which they operate. When states go too far, wars protract, costs spiral, and states obtain fewer benefits. The contrast between successes such as Britain in the Seven Years’ War and Japan in the Russo-Japanese War contrast with examples of overreach by the United States since 1945. After the Incheon landing in September 1950 shattered the North Korean army and led to the rapid reconquest of territory controlled by the Republic of Korea prior to the North’s invasion, the United States ended up pressing up the peninsula into North Korea and toward China, lured in part by an emphasis on what it was capable of. This aggression, however, precipitated China’s entry into the war, which protracted the conflict, raised the costs, and may have brought the war to a less desirable armistice. Similar decisions in conflicts in Kuwait in 1991, Afghanistan in 2001, and Iraq in 2003 have produced a mixed record of success.
Political and military leaders of maritime states gain their greatest advantages when they understand the margins under which they operate.
In such circumstances, reassessment can lead maritime states to potentially recalibrate. One form of reassessment is withdrawal, which occurs when involvement surpasses the value of the sought-after objectives. Both Britain in Corbett’s lifetime and the United States since 1945 have found, however, that committing forces is easier than withdrawing them. Once intervention has occurred, a combination of sunk costs in blood and treasure, inertia, the exposure of partners, and the feeling that withdrawal would cause international loss of credibility has made ending commitments difficult, even when costs exceed the value of the object. Some claim withdrawing is a sign of weakness—as occurred in 2021 at the end of American involvement in Afghanistan—but the effects of withdrawals on maritime credibility are debated, and require years if not decades to assess.
A contrasting perspective might emphasize that reassessment and withdrawal from South Vietnam gave the United States an opportunity to concentrate on other theaters in the Cold War and pursue new forms of advantageous engagement, such as President Nixon’s decision to go to China.81 A maritime state can accomplish this type of realignment far more effectively than a continental state.
Reassessment can also lead to opening new theaters in ongoing wars. During the Wars of the French Revolution and Napoleon, British leaders grappled with where to use its small army to obtain maximum strategic effects. These leaders generally gained small-scale successes, especially outside of Europe, by seizing the colonial possessions of their opponents. Even when Britain intervened in Europe, however, naval dominance afforded options, because the navy provided an exit strategy that limited the potential for manpower losses and helped terminate costly extended engagements. When the situation proved disadvantageous, British leaders had the option of using the navy to extract their land forces. And eventually, late in the Napoleonic Wars, leaders found a theater in Spain and Portugal where it was possible to obtain disproportionate strategic effects with a small army. Corbett revealed, “The real secret of Wellington’s success—apart from his own genius—was that in perfect conditions, he was applying the limited form to an unlimited war.”82
Reassessing is never easy. Corbett watched from afar as Japanese leaders grappled with this conundrum in the Russo-Japanese War, and saw even greater challenges when his own country wrestled with these issues in the First World War. The United States since 1945 has engaged in similar discussions on several occasions, including Korea, Vietnam, Kuwait, Iraq, and Afghanistan. In each case, the geographies of Britain, Japan, and the United States provided options for reassessment that would not have been possible if they had shared land borders with their opponents. These opportunities can, however, be squandered if the leaders fail to think critically, but reassessment provides maritime states with significant opportunities to use naval dominance in combination with the geography to limit failure.
Looking Forward
Naval dominance coupled with geography have insulated the United States from catastrophic conventional defeat and enabled pursuit of expansive global objectives. America’s global position in the post-1945 world would have been far shakier without this foundation.
The post-1945 period, however, has demonstrated another important truth: The advantages provided by geography and naval power narrow when maritime states attempt to secure objectives in distant lands. Decisions to become involved overseas have proven more effective when US leaders have looked at available means as a prerequisite while focusing on attainable ends, and accurately accounting for the costs required to achieve them. Just because US political leaders, or even its citizens, may wish to become involved in a conflict, the use of force might not yield the desired results at an acceptable cost. Making this determination requires leaders to consider the unique characteristics of each decision for war in relation to the value of long-term grand strategic objectives, a thorough understanding of the differences between limited and unlimited political objectives, and a willingness to accept the advantages of the former over the latter.
Though the United States has generally possessed the means to intervene, geography may be such that involvement can only occur at a disadvantage. The United States has obtained its greatest strategic effects overseas when it has employed isolation effectively (in terms of both geography and diplomacy), and worked with partners to ensure that US naval power and partner land power reinforce each other. When isolation is not possible, geographic disadvantage can be mitigated by securing international partners who are willing to sacrifice for the maritime state’s objectives. When the maritime state cannot achieve acceptable outcomes, the opportunity to reassess can potentially expand its margins for success. Though this decision can be painful, especially after experiencing sunk cost, recalibration is especially useful for the maritime state.
As Corbett so poignantly argued, not all competitions, conflicts, and wars are the same. US leaders should avoid the temptation to think that a single strategy will face down every threat. The period since 1945 suggests that the challenges that emerge will be many and often unanticipated, and Corbett’s theory helps us to illuminate and sharpen US options in an era of intensifying maritime competition.
Kevin D. McCranie is the Philip A. Crowl Professor of Comparative Strategy at the US Naval War College. His most recent book is Mahan, Corbett, and the Foundations of Naval Strategic Thought.
Acknowledgments: I would like to thank the two anonymous reviewers for their insightful comments and suggestions along with the editors of the Texas National Security Review for the time and effort they devoted to make this article much stronger.
The positions expressed in this article are my own. I do not represent the Naval War College, the US Navy, the Department of Defense, or the US government, and my views are not necessarily shared by them.