This study of Civil War–era politics explores how German immigrants influenced the rise and fall of white commitment to African-American rights. Intertwining developments in Europe and North America, Alison Clark Efford describes how the presence of naturalized citizens affected the status of former slaves and identifies 1870 as a crucial turning point. That year, the Franco-Prussian War prompted German immigrants to reevaluate the liberal nationalism underpinning African-American suffrage. Throughout the period, the newcomers’ approach to race, ethnicity, gender, and political economy shaped American citizenship law.