Introduction

One might say that the physical seems little more than the wooden hilt, while the moral factors are the precious metal, the real weapon, the finely-honed blade. Carl von Clausewitz

WHY DO NATIONAL MILITARY ORGANIZATIONS differ in their cohesion? Why do some countries' militaries fight hard when facing defeat, while others collapse? Why are some countries better than others at creating and sustaining cohesive armed forces in war? Consider, for example, the performance of the German military in World War II. Even when defeat appeared inevitable, the Wehrmacht fought tenaciously, prolonging the war and adding to the tremendous suffering it had already inflicted. In contrast, the battlefield determination of French armed forces varied widely in 1940, with some units offering stiff resistance, while others dissolved at crucial moments. As a result, France could never recover from initial German breakthroughs in early May 1940, and its military leaders, fearing an internal insurrection, pressured the civilian politicians to capitulate in late June.

What accounts for the greater cohesion of the German Army? Why did French armed forces disintegrate with their country's survival at stake? Traditional definitions of military power that focus on material capabilities offer only some clues as to why national militaries differ in their performance. Although knowing how many tanks and troops a country can send into battle can occasionally serve as a good predictor of how its military might perform in war, material capabilities alone cannot tell the entire story. Military cohesion, or the capacity of national armed forces to fight with determination on the battlefield, and to keep fighting even when a war appears lost, also plays an important role.

The historical record suggests no countries are alike in their military cohesion. Some countries can field armies capable of overcoming deficiencies in military hardware through their determination. Similarly, other countries bring superior military capabilities to the battlefield, but they cannot match their opponent's tenacity. Both France and the United States painfully discovered the importance of military cohesion while fighting in Vietnam. The balance of capabilities suggested that the North Vietnamese stood very little chance in their struggles against the Western Powers. In the end, however, strong military cohesion helped North Vietnam to outlast its opponents and emerge victorious. Battlefield determination and the staying power to endure a long, painful war trumped the balance of forces. Today, a similar dynamic appears at work in Afghanistan. The Taliban have proven a "tenacious and determined" foe hindering the nation-building efforts of the United States and its NATO allies. The pervasive nature of the insurgency has led some analysts to worry that sectarian divides in the newly raised Afghan National Army will undermine its military cohesion. Victory or defeat frequently depends on which side can field the more cohesive force.

In this study, I use the term "military cohesion" to describe two characteristics of a country's armed forces in war: (1) the capacity to fight with determination and flexibility on the battlefield; and (2) the ability to resist internal pressures to collapse as the likelihood of winning a war decreases. Military cohesion, therefore, refers to both battlefield performance as well as the staying power of a country's armed forces to endure difficult strategic circumstances without disintegrating. Traditionally, the literature uses cohesion to discuss the ability of small units, such as squads or platoons, to fight with determination and staying power. I broaden the concept of cohesion to encompass all of a country's military organizations during war.

Scholars have advanced two kinds of arguments to explain why some countries can create and sustain cohesive militaries, while other countries cannot. One view argues that military cohesion grows out of the strong bonds of loyalty that soldiers form inside small units, such as platoons or squads; soldiers fight for their buddies, not for grand political causes. This claim, however, ignores instances where militaries fought hard even when they lacked small-unit bonds, as a result of faulty personnel policies, internal divisions, or high rates of casualties during war. Another view argues that ideology, and not small-unit ties, motivates a country's armed forces to fight hard. By forging strong connections between soldiers and their nations, ideologies create cohesive militaries, capable of enduring long and costly wars. In this view, militaries fight with a high degree of cohesion because of nationalism or devotion to democracy. Of course, sometimes militaries respond to ideological rallying cries, but at other times they ignore them. Nationalism and democracy galvanized France in World War I but failed to do so in World War II. Ideologies could play an important role, but the conditions under which they promote military cohesion remain unclear.

SUMMARY OF THE ARGUMENT

This book presents what I call cohesion theory to explain why national militaries differ in their staying power and battlefield determination. My argument builds on insights from both the rationalist and social constructivist literatures on group solidarity. The core idea underpinning my theory is that any large group, including a country's armed forces, motivates members to sustain collective action by both promoting and enforcing norms of unconditional loyalty among its members. Norms define individual member obligations to any group. Groups remain cohesive even under challenging circumstances because these norms motivate some members to remain committed to group goals. At the same time, these hard-core group members pressure and coerce less motivated members to do the same.

According to the theory, the relationship between a government and its military organizations determines the cohesion of its armed forces during war. Specifically, the cohesion of a country's military depends on two explanatory variables: (1) the degree of regime control over a population; and (2) the degree of autonomy the armed forces possess for training. With a high degree of control, the regime can promote an ideology of unconditional loyalty and enforce it through coercion. This level of control requires both a national ideology that demands unconditional loyalty, such as communism, fascism, or nationalism, combined with a highly repressive government with no civil society to oppose it. Regimes that dominate their societies in this fashion bolster military cohesion by creating hard-core supporters in the armed forces who fight with determination and pressure others to display a similar commitment. Some personnel are true believers, with strong ties to the regime, while others feel compelled to fight.

For many regimes, however, obtaining a high degree of control over society is too difficult...