In The Shadow of the Past, Gregory D. Miller examines the role that reputation plays in international politics, emphasizing the importance of reliability—confidence that, based on past political actions, a country will make good on its promises—in the formation of military alliances. Challenging recent scholarship that focuses on the importance of credibility—a state’s reputation for following through on its threats—Miller finds that reliable states have much greater freedom in forming alliances than those that invest resources in building military force but then use it inconsistently.

To explore the formation and maintenance of alliances based on reputation, Miller draws on insights from both political science and business theory to track the evolution of great power relations before the First World War. He starts with the British decision to abandon "splendid isolation" in 1900 and examines three crises—the First Moroccan Crisis (1905–6), the Bosnia-Herzegovina Crisis (1908–9), and the Agadir Crisis (1911)—leading up to the war. He determines that states with a reputation for being a reliable ally have an easier time finding other reliable allies, and have greater autonomy within their alliances, than do states with a reputation for unreliability. Further, a history of reliability carries long-term benefits, as states tend not to lose allies even when their reputation declines.