The Transylvanian Question—the struggle between Hungary and Romania for control of Transylvania—seems at first sight a side-show in the story of the Nazi New Order and the Second World War. These two allies of the Third Reich spent much of the war arguing bitterly among themselves over Transylvania's future; Europe's leaders, Germany and Italy, were drawn into their dispute to prevent it from spiraling into a regional war. But precisely as a result of this interaction, the story of the Transylvanian Question offers a new way into the history of the European idea—how state leaders and national elites have interpreted what "Europe" means and what it does. For tucked into the folds of the Transylvanian Question's bizarre genealogy is a secret that no one ever tried to keep, but that has remained a secret nonetheless: small states matter. The perspective of small states puts the struggle for mastery among its Great Powers into a new and perhaps chastening perspective. In short, when we look closely at what people in small states think and how they behave, the history of twentieth-century Europe looks suddenly very different.