Escaping the Deadly Embrace: How Encirclement Causes Major Wars

By Andrea Bartoletti

Encirclement, Andrea Bartoletti argues, is an essential strategic possibility of the international system and a key trigger of major war. Using historical case studies, Escaping the Deadly Embrace examines how great powers try to escape the two-front war problem and seek to preserve their security.

Encirclement is a geographic variable that occurs in the presence of one or two great powers on two different borders of the surrounded great power. The surrounding great powers may not have the capacity to initiate a joint invasion. Yet their threatening presence triggers a double security dilemma for the encircled great power, which has to disperse its army to secure its borders. When the surrounding great powers become capable of launching a two-front attack, the encircled great power initiates war. This situation, disastrous in itself, can also lead to war contagion when other great powers intervene in the new conflict owing to the rival-based network of alliances.

Combining archival work and historiographical analysis, Escaping the Deadly Embrace demonstrates the efficacy of this by assessing three major wars: the Italian Wars, the Thirty Years' War, and World War I. These findings, Bartoletti shows, have important implications for future major wars. Challenging the current focus on the US-China rivalry, he argues that the most concerning strategic scenario is the encirclement of China by India and Russia.

• Language: English
• Publisher: Cornell University Press
• Release date: Nov 15, 2022
• ISBN: 9781501765933

Book preview

Cover: Escaping the Deadly Embrace, How Encirclement Causes Major Wars by Bartoletti, Andrea.

Escaping the Deadly Embrace

How Encirclement Causes Major Wars

ANDREA BARTOLETTI

Cornell University Press

Ithaca and London

Someone asked Gurdjieff, Can something be done to stop wars? He said, Nothing can be done—because those who are fighting, they are fast asleep, and those who are pacifists, they are fast asleep. And everyone is going on in a sleep. These happenings are natural, inevitable. Unless man is awake, nothing can be changed, because these are all just by-products of his sleep. He will fight; he cannot be stopped from fighting. Only the causes can be changed.

—Osho, The Book of Secrets: 112 Meditations to Discover the Mystery Within

Contents

Acknowledgments

Introduction

1. A Theory of Encirclement and Major War

2. France and the Italian Wars

3. France and the Thirty Years’ War

4. Germany and World War I

5. The Origins of Modern Major Wars

6. The Future of Major War

Notes

Bibliography

Index

Acknowledgments

If I had to explain where the association between encirclement and major war came from, I honestly could not answer. In the initial phase of research on the causes of major wars, I found a quote on encirclement and war by Richelieu that inexplicably made complete sense to me. That eureka moment, however, would not have turned into this book without all the support I received. As with any project that takes years to complete, there are several people who have made important contributions to this book and whom I want to thank.

The Department of Political Science at the University of Chicago has been the ideal place to stimulate my intellect and define my area of expertise. John Mearsheimer, Paul Poast, and Austin Carson helped me greatly with their knowledge and mentorship. Each person has taught me specific lessons and tricks on how to become a scholar, but the enthusiasm and commitment that Austin has shown in all those years have been invaluable to me. My gratitude also goes to the Workshop of International Politics at the University of Chicago, where I received excellent feedback on an earlier draft of this book. I also want to thank all the faculty and administrative members at the University of Chicago for creating an engaging and inclusive environment.

Although COVID-19 prevented me from physically joining Stanford University, my year as postdoctoral fellow at the Center for International Security and Cooperation (CISAC) has been important to complete this book. I thank Harold Trinkunas, Rose Gottemoeller, and Steven Pifer for their ability to keep me engaged remotely and for their suggestions on the policy implications of this book. I also want to thank the CISAC Research Seminar and all the CISAC fellows for providing feedback on the last draft of this book.

A fundamental contribution to the last version of this manuscript comes from the helpful comments of Bob Art and of an anonymous reviewer. My gratitude also goes to Michael McGandy, Michelle Witkowski, Clare Jones, and everyone at Cornell University Press who guided me through the publication process.

Even though I started my research on the origins of major wars at the University of Chicago, I cannot overlook my time at Università degli Studi di Firenze. I would like to express special thanks to Luciano Bozzo for his excellent teaching style that sparked my interest in international relations.

Heartfelt thanks go to my friend Maura Cremin for not only her feedback on the manuscript but most important, for all the years we spent together at the University of Chicago. I doubt that I would have graduated without finding someone who shares the same love for dark humor.

My final acknowledgment goes to my parents, Marco and Cinzia, for their unconditional love. My gratitude is even greater because they never failed to be by my side, even when they did not fully understand what I was doing with my life. The publication of this book is also the result of their unwavering support since I was a child.

Introduction

Surrender. You’re surrounded!

In any movie with a hostage standoff, these words are the nightmare for every criminal. Surrounded by a cordon of police and with no way out, the bad guys have two drastic and opposite choices: fight for their freedom with the serious risk of death, or surrender and end up in jail. This desperate situation rarely has a successful conclusion.

This dreadful scenario is not unique to movies. The presence of great powers on two different borders—encirclement—has been considered the greatest threat to state survival from ancient times to contemporary international politics. As historian Victor Hanson emphasizes, Why did Athens risk a campaign that might involve facing the Boeotians? Again, it was the old-age desire to be free of a two-front war, the specter that later haunted Rome when it faced the Carthaginians and Philip V of Macedon, the traditional German dilemma of being wedged between Russia and France, and the predicament America found itself in during World War II, with both Pacific and European theaters.¹ Encirclement lies at the origins of major wars, but we still lack a theory that analyzes the impact of the two-front-war problem on security competition, alliance formation, and great-power war. The main purpose of this book is to fill this gap.

The Topic: Encirclement and Major War

Encirclement is a geographic variable that has been overlooked by scholars. Jack Snyder introduces the concept of self-encirclement, which he considers the result of strategic overcommitments that are driven by imperialist myths of domestic elites rather than the main cause of war.² Moreover, the findings of this book contradict Snyder’s predictions on state behavior since they show that the encircled great power does not initiate a conflict to expand but rather to prevent the surrounding great powers from launching a simultaneous invasion.

Although encirclement has not been theorized, the role that the two-front-war problem plays in the outbreak of major wars is often mentioned by International Relations (IR) scholars. Dale Copeland emphasizes how encirclement was a critical factor in the Nazi decision to invade Poland in 1939: Hitler’s conference with senior commanders on May 23 shows how impending encirclement and others’ accelerating rearmament had convinced him to speed up plans to invade Poland.³ John Mearsheimer suggests that the German fear of encirclement contributed to the outbreak of World War I: The German decision to push for war in 1914 was not a case of wacky strategic ideas pushing a state to start a war it was sure to lose. It was … a calculated risk motivated in large part by Germany’s desire to break its encirclement by the Triple Entente, prevent the growth of Russian power, and become Europe’s hegemon.⁴

The two-front-war problem has not been ameliorated by the advent of nuclear weapons. As Robert Gilpin notes, the Soviet Union deeply understood the dangers of encirclement: As long as western Europe lacks political unity, Japan remains weak militarily, and China continues in a backward state, this danger is minimized, though by no means eliminated. Certainly, the Soviet Union has a genuine fear of a surrounding alliance composed of these neighboring powers and the United States.⁵ According to Stephen Walt, the possibility of facing a joint attack on two different fronts is what heightened the security dilemma between the Soviet Union and the United States: "Geography places the Soviet Union against virtually all the other important and powerful countries in the world. If a Soviet strategic planner could be granted one wish, it should be to move his country somewhere else.… The Soviet response to this unfavorable situation is both predictable and self-defeating. Faced by a surrounding coalition of vastly superior latent resources, the Soviet Union devotes a large share of its national income to amassing military power.… Like Wilhelmine Germany and contemporary Israel, the Soviet Union may view an offensive capability as desirable if it must fight on several fronts."⁶

In sum, encirclement is considered a uniquely dangerous situation that has a profound impact on international politics. Several scholars mention encirclement in passing, but they do not elucidate how it leads to major war. In short, they do not explain how encirclement works.

The Argument in Brief

What are the origins of major wars? The simple answer is encirclement, a situation that creates a two-front-war problem for the encircled great power, because it shares two different borders with one or two great powers (surrounding great powers).⁷

Being a geographic variable, encirclement is constant and cannot explain the variation of war and peace. I identify an intervening variable—the increase of the invasion ability of the immediate rival—as the causal mechanism that links encirclement to the outbreak of major wars. This variable is not a function of state behavior or gradual power shifts in the future but rather of imminent, operational changes that alter the ability of the immediate rival to launch a successful invasion.

Since the immediate rival is the state that poses the greatest threat to survival based on its ability to launch a successful invasion, the surrounding great powers and the encircled great power are mutual immediate rivals.⁸ When the surrounding great powers increase their operational capability to launch a simultaneous invasion, the encircled great power initiates an attack against one of the surrounding great powers. The other great powers are dragged into this dyadic conflict as part of the existing rival-based network of alliances because they want to prevent their own immediate rival from increasing its invasion ability. Briefly, encirclement leads to the outbreak of major wars through a three-step process: double security dilemma, war initiation, and war contagion.

The two-front-war problem creates a uniquely dangerous situation. The encircled great power stands a good chance of being defeated, even when it has military superiority over each of the surrounding great powers, because it cannot concentrate its military forces against a simultaneous attack on multiple fronts. This strategic nightmare compels the encircled great power to eliminate its encirclement by seeking alliances and establishing buffer zones that would hinder the ability of the surrounding great powers to launch a joint attack. On the other hand, the measures that the encircled great power undertakes to eliminate its two-front-war problem decrease the security of the surrounding great powers which, in turn, conduct similar countermeasures that tighten their grip on the encircled great power. Therefore, encirclement engenders a double security dilemma (step 1) that leads to the formation of two alliance blocs and to a spiral of intense security competition that increases the likelihood of war.

The dynamics of the double security dilemma provoke the outcome that the encircled great power is trying to prevent. The surrounding great powers do not always have the ability to initiate a joint attack, but an increase of their invasion ability changes the threat environment of the encircled great power and gives the surrounding great powers the operational capability to launch a simultaneous invasion. Increases in the invasion ability of the surrounding great powers can take two forms: first, the surrounding great powers eliminate all the (internal and external) security threats that prevent them from concentrating their forces; second, they annex territory along the borders of the encircled great power, thereby creating a new gate for invasion. An increase in the invasion ability of the surrounding great powers imminently threatens the survival of the encircled great power because a simultaneous invasion becomes a concrete possibility. Facing the looming prospects for a two-front war, the encircled great power initiates an attack against one of the surrounding great powers (step 2). Like an animal that attacks its predator to escape when feeling trapped, the encircled great power resorts to war as a measure of last resort when it faces the choice of either fighting or surrendering.

The attempts of the encircled great power to eliminate its two-front-war problem have a profound impact not only on war initiation but also on the last step on the path to major war: war contagion (step 3). The other great powers in the system are dragged into the dyadic conflict between the encircled great power and one of the surrounding great powers because of the existing rival-based network of alliances that emerged during the double security dilemma. This system of alliances links the survival of all the members of each bloc, and it ties the separate dyadic antagonisms of immediate rivals in one unified zero-sum game. The attack of the encircled great power triggers a cascade of military interventions. Each great power in the system tries to prevent an increase in the invasion ability of its own immediate rival, which could happen if it loses a great-power ally (by military defeat or defection) or if the immediate rival annexes territory along its borders. Like an earthquake whose devastation radiates out from its epicenter, the attempts of the encircled great power to escape the deadly embrace of the surrounding great powers lead to the progressive involvement of all the other great powers in a major war.

Implications of the Argument

This book makes three main theoretical contributions. First, it elaborates a new explanation on the origins of major wars (encirclement theory). A great power that faces a two-front-war problem initiates war with the limited goal of preventing a simultaneous invasion by the surrounding great powers and it attacks even if it lacks power preponderance. In turn, the findings of this study challenge those arguments that consider major wars to be the result of the most powerful state’s attempts to either achieve or preserve its hegemony. Second, encirclement theory highlights the importance of quick operational shifts in the ability to invade of the surrounding great powers, rather than gradual power changes, as the factor that links the geographic variable of encirclement to the outbreak of major wars. Third, this work outlines an argument that explains both endemic characteristics of state behavior (such as security competition and alliance formation) and the dynamic outbreak of major wars. Existing theories usually account for separate steps that lead to major wars, but they fail to connect them in a comprehensive explanation. Instead, encirclement theory purports to explain both why and when major war begins.

In addition to these theoretical contributions, this book provides insights on the prospects for future major wars. Some scholars consider great-power war to be anachronistic, while others consider the rise of China and US incentives to launch a preventive strike to stop its relative decline to be a likely scenario of conflict. Instead, I argue that the most dangerous situation will ensue from the encirclement of China, which currently shares borders with one great power (Russia) and with an emerging one (India).

Plan of the Book

The remainder of the book is structured as follows. In chapter 1, I lay out a theory that links encirclement to major war. After a general overview of the argument, I define the key variables of my argument: encirclement, the invasion ability of the surrounding great power, major war, and great-power status. Then I unpack my theory in each of the three steps that can provoke the outbreak of major war. Before delineating the research agenda of this study, I identify the main competing explanations on the origins of major wars.

Chapter 2 provides an assessment of encirclement theory in the Italian Wars (1521–1559). I outline how the encirclement of France by Austria and Spain emerged, triggering a double security dilemma that revolved around the French attempts to create a buffer zone in northern Italy with the goal of breaking the lines of communication between the surrounding great powers. After Charles V inherited the Spanish and Austrian possessions of the Hapsburg in 1519, France initiated a series of attacks to prevent him from controlling the Duchy of Milan. Then I move to the analysis of the motivation for intervention by the other European great powers. I conclude by showing how the findings of this case study undermine alternative explanations.

In chapter 3, I evaluate my argument in the Thirty Years’ War (1635–1648). After providing an overview of the historiographical debate on the origins of this major war, I explore how the Spanish encirclement of France triggered a double security dilemma that led to the formation of a rival-based network of alliances and to the adoption of increasingly aggressive measures that increased the chances of war. Then I show that France decided to launch an attack against Spain as a measure of last resort to prevent actualized encirclement, which would have resulted from an increase in the invasion ability of the Hapsburg. I move to the assessment of the logic of war contagion by showing that the Swedish and Austrian interventions on the side of their allies (France and Spain, respectively) were driven by concerns that their own immediate rival would increase its invasion ability. I conclude the chapter by showing how theories that stress hegemonic ambitions or the role of religion cannot explain the outbreak of this major war.

Chapter 4 shows that the encirclement of Germany by France and Russia led to the outbreak of World War I (1914–1918). After analyzing Otto von Bismarck’s and Wilhelm II’s attempts to break the deadly embrace by splitting the Franco-Russian alliance, I identify the Russian construction of strategic railroads in Poland as the increase of the invasion ability that led to the escalation of the July crisis. I explore the logic of intervention of the other great powers after Germany declared war on Russia, and I end the chapter by underlining the shortcomings of existing explanations of the outbreak of World War I.

In chapter 5, I provide an overview of all the other major wars in modern history. I start by outlining the three major wars that were initiated by Louis XIV (Franco-Dutch War, Nine Years’ War, and the War of the Spanish Succession), the two major wars that were caused by the encirclement of Prussia (War of the Austrian Succession and the Seven Years’ War), and the French Revolutionary and Napoleonic Wars. Then I analyze in more detail the main anomaly for encirclement theory: the outbreak of World War II.

In chapter 6, I explore the prospects for future major war. After debunking the myth that the nuclear revolution has made major wars anachronistic, I identify China as the next encircled great power that could initiate a major war to eliminate its two-front-war problem. I conclude this book by highlighting future directions for studies focusing on the role of encirclement.

CHAPTER 1

A Theory of Encirclement and Major War

As noted in the introduction, scholars generally consider the two-front-war problem a uniquely dangerous situation that seriously undermines the survival of the encircled great power. Nevertheless, we lack an explanation of how encirclement leads to the outbreak of major wars. In this chapter, I develop a new theory that aims to fill this gap in the literature.

Major wars (dependent variable) have their foundations in the encirclement of one great power (the independent variable) and unfold through a three-step process, the causal mechanism of which is the result of changes in the invasion ability of the immediate rival (the intervening variable).

Encirclement is present when a great power (encircled great power) shares two different borders with one or two great powers (surrounding great powers). This two-front-war problem creates a double security dilemma for the encircled great power because it must disperse its forces for securing its borders against a potential invasion from different fronts (step 1). The encircled great power adopts two major strategies to prevent the surrounding great powers from acquiring the ability to launch a simultaneous invasion: seeking allies and establishing buffer zones. The measures that the encircled great power adopts to eliminate its two-front-war problem trigger the other two steps that lead to the outbreak of major wars.

The first outcome of the double security dilemma has a direct impact on war initiation (step 2). The strategies that the encircled great power undertakes to eliminate its two-front-war problem alarm the surrounding great powers because seeking external support from other great powers or creating buffer zones could not only improve the security of the encircled great power, but it could also increase its ability to launch an attack from more defensible borders. Accordingly, the surrounding great powers respond by adopting similar countermeasures that could result in improvements in their operational capacity to launch a simultaneous invasion.

Given that the surrounding great powers are the immediate rivals of the encircled great power, as they are the states that pose the greatest threat to its survival, an increase of their invasion ability engenders a fundamental change in the threat environment of the encircled great power. Encirclement creates the two-front-war problem (latent encirclement), but the surrounding great powers often lack the operational capability of conducting a joint attack. Increases in the invasion ability of the surrounding great powers give them the operational capability to launch a joint attack (actualized encirclement) and to conquer part or all the territory of the encircled great power.

Change in the operational ability to launch an invasion is different from relative power shifts and it is much more dangerous: the former is rapid and drastic, creating the possibility of an imminent invasion and occupation of territory; the latter is usually gradual and takes years before it is transformed in actual ability to attack an adversary.¹ Therefore, the encircled great power launches an attack against one of the surrounding great powers as a measure of last resort to prevent actualized encirclement, even if it risks triggering a two-front war against the surrounding great powers.

The second consequence of the double security dilemma has a direct influence on war contagion (step 3). During the double security dilemma, the encircled great power attempts to eliminate its two-front-war problem by seeking external support from other states that regard the surrounding great powers as their own immediate rival. This strategy compels the surrounding great powers to form an alliance among themselves and with those states that consider the encircled great power or one of its allies their own immediate rival. The result is the formation of a rival-based network of alliances, where each great power joins the opposite bloc of its own immediate rival.

This checkerboard system of alliances is activated by the dyadic war between the encircled great power and one of the surrounding great powers. The other great powers are dragged into this conflict to prevent increase in the invasion ability of their own immediate rival, which could happen by losing a great-power ally (by military defeat or defection) or if a great power annexes territory along the borders of its immediate rival. Therefore, this rival-based system of alliances entwines the survival of all the members of each bloc, and it ties the separate dyadic antagonisms of immediate rivals in one unified zero-sum game.

As dropping a stone into a lake creates a ripple effect that radiates from its center to the banks, the attempt of the encircled great power to escape its deadly embrace is the common thread that ties the double security dilemma, war initiation, and war contagion. Coming full circle, encirclement lies at the origins of major wars. Figure 1.1 illustrates the logic of my argument.

In the remainder of this chapter, I elaborate on the logic of my argument. I start by defining the key components of my theory. After emphasizing the primary role of geography, I examine how encirclement lies at the origins of major wars through the unfolding of three steps: double security dilemma, war initiation, and war contagion. Then I analyze the main alternative explanations on the origins of major war. I conclude by outlining the research agenda and case selection of this book.

A flowchart that shows how encirclement and major war are connected through the unfolding of three steps: double security dilemma, war initiation, and war contagion.

Figure 1.1. Encirclement at the origins of major wars

Definitions

My explanation for the outbreak of major wars introduces new concepts and refines existing ones. To clarify the logic of my argument, I identify its key components. I begin this section by offering a definition of the main variables of my theory: encirclement, the invasion ability of the immediate rival, and major wars. Moreover, to support my claim that the number of great powers and the distribution of power among them do not affect the incidence or the outbreak of specific major wars, I define the unit level of analysis of this book (great-power status).

INDEPENDENT VARIABLE: ENCIRCLEMENT

The conventional definition of encirclement refers to its military component. It is essential to clarify that I adopt a different terminology that emphasizes the strategic aspect of the two-front-war problem.

Military strategists consider encirclement a tactical operation in which the attacker can surround its opponent.² The defender finds himself in a desperate situation that leaves him with the choice of either surrendering or resisting multiple assaults by superior forces. As Carl von Clausewitz notes, The risk of having to fight on two fronts, and the even greater risk of finding one’s retreat cut off, tend to paralyze movement and the ability to resist, and so affect the balance between victory and defeat. What is more, in the case of defeat, they increase the losses and can raise them to their very limit to annihilation. A threat to the rear can, therefore, make a defeat more probable, as well as more decisive.³

The concrete dangers of being surrounded by hostile troops are shown by numerous historical examples, where the use of this military tactic led to the complete destruction of the enemy’s army: From the time of Alexander at Cannae, through the Soviets at Stalingrad, to the North Vietnamese at Dien Bien Phu, the history of warfare has been filled with examples of how one army overcame an opponent by encirclement. Each instance led to the destruction of the enemy and a strategic and operational victory.⁴ Strategic encirclement presents states with a more complicated predicament because the encircled great power has to disperse its forces across different war theaters, and it can be defeated even if it is more powerful than each of the surrounding great powers.⁵

Encirclement is a geographic variable that occurs in the presence of one or two great powers on two different borders of the encircled great power. Therefore, the two-front-war problem can take two possible forms:

1) Two surrounding great powers, both of which share a different border with the encircled great power. The most illustrative case is the situation of Germany since its unification in 1871. Germany was encircled by Russia on the eastern border and France on the western border (surrounding great powers).

2) One great power that shares two separate and distinct borders with the encircled great power. For example, the United Hapsburg under Charles V (surrounding great power) controlled territories along the southern, eastern, and northern frontiers of France.

In modern history, there have been multiple examples of great powers that faced the two-front-war problem. Based on my definition of latent encirclement, I identify the following cases (table 1.1).

It is essential to clarify when the two-front-war problem is absent. First, a great power is not encircled if it shares borders with states that have not achieved great-power status. For instance, the United States is not encircled by Mexico and Canada. Second, diplomatic behavior does not affect latent encirclement, a geographic variable. The hypothetical alliance of one of the surrounding great powers does not eliminate the two-front-war problem. For example, Germany was still encircled between 1873 and 1880, when it was allied with Austria-Hungary and Russia in the League of the Three Emperors. Third, the encirclement of smaller states is beyond the scope of my theory because I consider this situation not to be conducive to major wars. Fourth, a great power does not face encirclement if it shares one border with a great power and another border with a minor state that can be overrun by a second great power. The territory of the minor power might be nothing more than a speed bump because of its incapability to deny the passage of foreign troops; however, the lack of territorial contiguity with two great powers does not strictly engender a two-front-war problem. For instance, Nazi Germany was not encircled by France and the Soviet Union because of the presence of Poland, even if Hitler did not consider this geographic barrier to be sufficient for stopping a potential Soviet attack. Finally, I suggest that only continental great powers could be encircled. Technically, an insular state could be encircled if another great power could sustainedly control all the sea lanes around it, but the difficulties of this enterprise and of launching amphibious assaults lead me to rule out latent encirclement for maritime great powers.

INTERVENING VARIABLE: INVASION ABILITY OF THE IMMEDIATE RIVAL

Encirclement is a geographic variable, and as such, it is constant; yet, my argument is not deterministic. I consider the invasion ability of the immediate rival to be the catalyst for war initiation (the decision of the encircled great power to attack one of the surrounding great powers) and for war contagion (the decision of the other great powers to intervene in this dyadic conflict).

The encircled great power and the surrounding great powers are mutual immediate rivals. Based on the type of threat environment of the encircled great power, which is a function of the operational ability of the surrounding great powers to launch a two-front war, I distinguish two possible layers of encirclement:

1) Latent encirclement occurs when the encircled great power has one or two great powers at two distinct borders, but there is no serious possibility of a two-front war. Although there is the potential of a simultaneous invasion by the surrounding great powers in the future, they lack the operational ability to launch a joint invasion in the present. Therefore, latent encirclement triggers the double security dilemma for the encircled great power, but it is insufficient to cause war initiation.

2) Actualized encirclement occurs when the surrounding great powers develop the operational capability to launch a joint attack against the encircled great power. Although a simultaneous attack by the surrounding great powers is not inevitable, actualized encirclement makes a two-front war a concrete probability in the present rather than a mere possibility in the future. An increase in the invasion ability of the surrounding great powers produces a fundamental change in the threat environment of the encircled great power because it gives the former the operational capability to launch a successful attack against the latter. Hence, the encircled great power initiates an attack against one of the surrounding great powers to prevent actualized encirclement.

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An increase in the invasion ability of the immediate rival also triggers war contagion, after the encircled great power attacks one of the surrounding great powers. The other great powers in the region are concerned with changes in the invasion ability of their own immediate rival because it is the state that poses the most serious threat to their survival due to a combination of geographic proximity and relative power.⁶ Each great power has its own immediate rival, but states do not share the same one. The other great powers in the region coalesce in a counterhegemonic coalition only in presence of a state with clear power preponderance.

It is important to emphasize that this variable is not the same as changes in states’ perceptions of their opponents’ strength or of increases in their military power.⁷ For instance, the mobilization of troops of one of the surrounding great powers along the borders of the encircled great power does not entail a shift in raw military capabilities, but it still causes the outbreak of hostilities. Moreover, the invasion ability of the immediate rival differs from gradual power shifts. Power transition theorists stress the role of exogenous changes in relative power as results of uneven economic growth. These power shifts, however, are rarely rapid enough to explain war initiation; quite the contrary, they are usually the consequence of war.⁸

To test the falsifiability of my argument, it is particularly important to compare increases in the invasion ability of the immediate rival with Dale Copeland’s dynamic differentials.⁹ Copeland identifies rapid and large power shifts in the future as the reason for the declining hegemon, while being more powerful than the rising challenger, launches a preventive war. Instead, an increase in the invasion ability of the immediate rival generates a concrete military advantage that a great power could use to coerce or invade its immediate rival in the present. I identify three important contributions of my theory that allow me to explain the dynamic outbreak of major wars.

First, I emphasize the role of the operational capability of the immediate rival to launch an invasion, an endogenous product of state behavior. The encircled great power does not fear an adverse power shift in the future but rather an imminent attack by the surrounding great powers. The second implication of my argument is that the encircled great power does not need to be relatively more powerful than each surrounding great power to initiate war. Third, changes in the invasion ability of the immediate rival have a territorial component that makes them extremely dangerous. Other increases in relative power, such as internal and external balancing, occur all the time without directly threatening the survival of other great powers and triggering a military response. Great powers primarily fear increases in invasion ability because they enhance the immediate rival’s operational capability to launch an attack on their national territory.

DEPENDENT VARIABLE: MAJOR WAR

To determine when a military conflict can be considered a major war, I start my analysis from Jack Levy’s distinction between great-power wars and general wars.¹⁰ Great-power wars require the presence of at least one great power on each side of the conflict. Levy classifies general wars as military conflicts that involve at least two-thirds of the Great Powers and an intensity exceeding 1,000 battle deaths per for million population.¹¹ Alternatively, Copeland considers major wars those military conflicts that involve all the great powers, that are fought at the highest level of intensity, and where there is a strong possibility that great powers may be eliminated as sovereign states.¹²

I consider these two definitions to be troublesome because they focus on the conduct or the potential outcome rather than the peculiar nature of major wars. First, the rationale behind Levy’s threshold for the onset of major wars (two-thirds of great powers) is unclear. If a major war is a sweeping phenomenon that shakes the foundations of the system, the survival of all