A comparison of the United States and Italy in the nineteenth century yields some remarkable similarities: In both instances, a relatively young country sought to cultivate liberal nationalist sentiments, economic progress, and technological modernization. At the same time, both Italy and the U.S. faced a direct threat to national unity in the form of a recalcitrant southern population, culminating in unprecedented bloodshed and social instability. While many historians have commented on these parallels, they have until now not been subject to a full scholarly study. Here, Enrico dal Lago provides a nuanced analysis of this era by examining the ideologies of American abolitionism and Italian democratic nationalism, the public personae of Abraham Lincoln and Camillo Cavour, and the bitter conflicts that threatened both nations beginning in 1861. His study provides powerful new insights into the histories of two countries, both on their own terms and in the wider context of the nineteenth-century Euro-American world.