Between 1848 and 1865 white southerners felt the grounds of nationhood shift beneath their feet. The conflict over slavery that led to the Civil War forced them to confront the difficult problems of nationalism. What made a nation a nation? Could an individual or a group change nationality at will? What were the rights and responsibilities of national citizenship? Why should nations exist at all?

As they contemplated these questions, white southerners drew on their long experience as Americans and their knowledge of nationalism in the wider world. This was true of not just the radical...