In May-June 1940 the Germans demolished the French Army, inflicting more than 300,000 French casualties, including more than 120,000 dead. While many historians have focused on France's failure to avoid this catastrophe, Kiesling is the first to show why the French had good reason to trust that their prewar defense policies, military doctrine, and combat forces would preserve the nation. Kiesling argues that France's devastating defeat was a consequence neither of blindness to the German military threat nor of paralysis in the face of it. Grimly aware of the need to prepare for another war with its arch enemy, French leaders created defense preparations and military doctrines in which they felt confident. Rather than simply focusing on what went wrong, Kiesling examines the fundamental logic of French defense planning within its cultural, institutional, political, and military contexts. In the process, she provides much new material about the inner workings of the French military, its relations with civilian leaders, its lack of adaptability, and its overreliance on an army reserve that was poorly organized, trained, and led. Ultimately, she makes a persuasive case for France's defense options and offers a useful warning about the utility of the "lessons of history." The lesson for contemporary policymakers and strategists, Kiesling suggests, is not that the French made mistakes but that nations and armies make policy and strategy under severe constraints. Her study forcefully reminds us how hindsight can blind us to the complexities of preparing for every next war.