The turbulent two decades between the end of World War I and the outbreak of World War II represent a period of broken balances, when the global and regional balances of power shattered by war never fully reconstructed. Indeed, the balance remained broken in several ways. The United States, the most powerful actor in the world, failed to play a balancing role commensurate with its power from its failure to ratify the 1919 Versailles Treaty until its late entry into World War II. The Soviet Union, after its political revolution of 1917, was relegated to the sidelines of international diplomacy, preventing it from having a major effect on the international balance of power. Germany, which was kept artificially weak by the disarmament and territorial amputation clauses of the Versailles Treaty, eventually slipped its shackles, once again breaking the fragile equilibrium on the European continent. Great Britain and France, both economically devastated, struggled to maintain adequate geopolitical power to maintain the ephemeral post–World War I order. Japan emerged to dislodge the European states as the principal power in East Asia. These broken balances posed serious challenges for the great powers, each of whom was compelled to devise grand strategies under spectacular constraints in order to navigate this turbulent period in world history. This era of broken balances, which British diplomat and historian E. H. Carr aptly called the Twenty Years’ Crisis, has had a profound impact on the study of international politics and the practice of statecraft. Now that decades have passed since these events, analysts have both the objectivity of temporal distance and a greater range of primary-source materials to shed light on the events of the interwar years. The time is ripe for a reassessment of great power politics and grand strategy during that important era.