During the nineteenth and twentieth centuries, the global Mennonite church developed an uneasy relationship with Germany. Despite the religion's origins in the Swiss and Dutch Reformation, as well as its longstanding pacifism, tens of thousands of members embraced militarist German nationalism. This book is a sweeping history of this encounter and the debates it sparked among parliaments, dictatorships, and congregations across Eurasia and the Americas. Offering a multifaceted perspective on nationalism's emergence in Europe and around the world, the book demonstrates how Mennonites' nationalization reflected and reshaped their faith convictions. While some church leaders modified German identity along Mennonite lines, others appropriated nationalism wholesale, advocating a specifically Mennonite version of nationhood. Examining sources from Poland to Paraguay, the book shows how patriotic loyalties rose and fell with religious affiliation. Individuals might claim to be German at one moment but Mennonite the next. Some external parties encouraged separatism, as when the Weimar Republic helped establish an autonomous “Mennonite State” in Latin America. Still others treated Mennonites as quintessentially German; under Hitler's Third Reich, entire colonies benefited from racial warfare and genocide in Nazi-occupied Ukraine. Whether choosing Germany as a national homeland or identifying as a chosen people, called and elected by God, Mennonites committed to collective action in ways that were intricate, fluid, and always surprising.