In This Review

The Twenty Years’ Crisis, 1919–1939: An Introduction to the Study of  International Relations
The Twenty Years’ Crisis, 1919–1939: An Introduction to the Study of International Relations
By Edward Hallett Carr
Macmillan, 1939, 312 pp.
A Study of War
A Study of War
By Quincy Wright
University of Chicago Press, 1964, 451 pp.
Makers of Modern Strategy: Military Thought From Machiavelli to Hitler
Makers of Modern Strategy: Military Thought From Machiavelli to Hitler
By Edward Mead Earle
Princeton University Press, 1943, 553 pp.

Editor’s Note: For our centennial issue, our reviewers each selected a set of books essential to understanding the past century and another set essential for imagining the century ahead.


Three important approaches to the study of war were established by books published during World War II. Carr finished his classic, an analysis of how things had gone wrong since World War I, just as a new global conflagration was beginning. The book is now seen as one of the foundational texts of realism, although Carr described it more as a correction of the increasingly influential and, in his view, naive utopianism that devised schemes for world government without regard for the abiding importance of national interest. Carr’s focus on military power, economic power, and the state’s ability to shape public opinion reinforced the realist character of the book. He sought to revise utopian assumptions about the inevitability of progress, but he wasn’t a total cynic: moral considerations, in his view, remained an important part of policymaking.

Wright’s two-volume magnum opus, the result of years of meticulous and comprehensive research by his team at the University of Chicago, was published in 1943. This work had a utopian objective: to provide the evidence and analysis to make possible the prevention and limitation of war. Wright identified four key factors that determined the likelihood of conflict: technology (mainly military), law (mainly international), forms of political organization, and key values. Peace required maintaining an equilibrium “among the uncertain and fluctuating political and military forces within the system of states.” Wright argued that leaders could make sound policy decisions only by paying attention, in granular and quantitative detail, to subjects as diverse as the properties of weapons systems, demographics, the observance of international law, polling data, and the content of newspapers. Later generations of scholars followed Wright’s path in crafting a scientific approach to international relations that depended on thorough data gathering and rigorous analytical methodologies.

Earle brought together a remarkable collection of essays to help explain the origins of strategy. In some respects, the impact of new forms of warfare, including the first atomic bombs, soon dated the volume. But the book’s abiding value was ensured by the ambitious historical sweep of Earle’s approach, his expansive definition of strategy—incorporating economic considerations and political context—and the quality of the individual contributions, including some by the leading historians of the time.

These three books capture the key themes that have emerged in Western thinking about strategy since the end of World War II. By far the most important development was the start of the nuclear age. The advent of the atomic bomb demanded a reappraisal of military strategy, an effort that was largely led by civilian analysts, of whom Schelling was the most original and imaginative. He was an economist with a lively mind and an eclectic approach, influenced by, but not bound to, game theory. The shared fear of nuclear war created incentives for the superpower antagonists to cooperate as well as compete; this interdependence was a fruitful area for game theory. Schelling addressed the key policy issues of the day, explored the credibility of commitments and tacit forms of bargaining, and developed such influential concepts as “the threat that leaves something to chance” (the risk of escalation that one cannot completely control) and “the reciprocal fear of surprise attack” (the idea that the probability of a surprise attack grows because each side fears what the other fears).

It might seem odd to include in this list the classic work of Carl von Clausewitz, the great Prussian theorist, first published in German in 1832. But the publication in 1976 of a new translation by Howard and Paret had a major impact on discourse about strategy. They made a book that had been generally described as dense and difficult accessible to a wider audience at a time when there was a revival of interest in conventional warfare. Their translation was controversial. Critics suggested that Howard and Paret distorted the meaning of the nineteenth-century text to make it more relevant to contemporary debates. Nonetheless, the significance of the work could not be denied. It reminded readers of some of Clausewitz’s most telling observations, including the importance of political purpose; the interplay of reason, chance, and passion; the inherent strengths of defense; the need to identify the enemy’s center of gravity as the best point to attack; and the importance of the culminating point when an advance runs out of steam.

Then there is the U.S. Army’s field manual. It is not a work of independent scholarship but a government document, more a product of its time than an enduring contribution to strategic thought. Yet it captured the insights of the United States’ senior military leadership as they struggled with the demands of two major counterinsurgency campaigns in Iraq and Afghanistan in the first decade of the twenty-first century. The manual was drafted with substantial contributions from academics and nongovernmental organizations and stressed the need to avoid conventional thinking about war. Instead, it drew on a tradition of thinking about revolutionary and guerrilla warfare that emphasized the importance of separating militants from the wider population, in part by relying more on a political process than on combat. The manual encouraged flexibility in military attitudes and behavior and pointed to the value of restraint. It was well received and widely read, and its lessons were applied successfully if briefly in Iraq during the 2007 surge of U.S. troops in the country. Afghanistan, however, exposed the problems when it came to applying its core messages.