This magisterial work focuses on the failure to prevent World War II. Realists and liberal defenders of the League of Nations have long contended that after World War I, France, the United Kingdom, and, above all, the United States should have formed a military alliance to contain Germany. Cohrs advances a less well-known argument. In his view, any European order based solely on military containment was doomed unless it addressed the deeper sources of all European conflicts from 1850 to the present: diverging claims of national self-determination, opposing economic and financial interests, and intense ideological strife between the political right, left, and center. Not enough was done at Versailles—and, the author sometimes seems to suggest, not enough could possibly have been done—to resolve these matters in ways that would have lent the settlement a critical measure of domestic and international legitimacy. This failure encouraged nondemocratic revisionist powers (notably, but not only, Hitler’s Germany) to make intractable demands, such as to revise the Treaty of Versailles and to restore lost territory, with fatal consequences for the postwar peace. Although this account owes much to classic works by the economist John Maynard Keynes and the sociologist Max Weber, among others, its sweeping synthesis and grounding in primary sources makes an impressive thousand-page read.