This volume explores the significance and meanings of “loyalty” in the Northern states during the Civil War. Collectively, these essays use the experiences of differing individuals or groups to illuminate the ways in which notions of loyalty were defined and contested. A number of patterns emerge. First, discussions of the term went beyond a narrow definition of loyalty as nationalism. Support for the government and for the Union cause was but one layer of potential meaning. The debate over what loyalty entailed, though, was not limited to proofs or expressions of patriotism. Strong allegiances to other social groups and their ideologies or interests coexisted with those to the perceived nation. Individuals often acted out of affinity for self, family, community, region, or ethnicity, and held principles that could work at cross-purposes to nationalism (Christian pacifism being an example of the latter). Multiple and overlapping layers of loyalty were not always mutually exclusive but the demands and suffering of war brought out inherent tensions and potential conflicts. These essays stress how such debates were not confined to the political arena. Discussions of loyalty intruded into many public and private spaces including homes, city streets, places of work and worship, and onto college campuses. Authors examine the significance of loyalty across fault lines of gender, social class and education, race and ethnicity, and political or religious affiliation. These differing vantage points reveal the complicated ways in which loyalties were defined, prioritized, acted upon, and related. Scholars of the Confederate home front have lit the way, examining in depth the pull of conflicting loyalties and their implications for Southern defeat. The Union may have prevailed but Northern society struggled with its own profound internal divisions. Historians have labored over parts of this story. We know a great deal, for instance, about political dissent and “Copper head” opposition. This collection pushes us to see how a fractious and diverse Northern people ultimately failed to reach consensus on what loyalty meant or how citizens in times of war might demonstrate it. It also suggests that the development of American nationalism had important limitations and ambiguities that the war exposed....