Alter-Nations: Nationalisms, Terror, and the State in Nineteenth-Century Britain and Ireland investigates how Victorian cultural production on both sides of the Irish Sea grappled with the complex relationship between British imperial nationalism and Irish anticolonial nationalism. In the process, this study reconceptualizes the history of modern nationhood in Britain and Ireland. Taking as its archive political theory, polemical prose, novels, political cartoons, memoir, and newspaper writings, Amy E. Martin’s Alter-Nations examines the central place of Irish anticolonial nationalism in Victorian culture and provides a new genealogy of categories such as “nationalism” “terror,” and “the state.” In texts from Britain and Ireland, we can trace the emergence of new narratives of Irish immigration, racial difference, and Irish violence as central to capitalist national crisis in nineteenth-century Britain. In visual culture and newspaper writing of the 1860s, the modern idea of “terrorism” as irrational and racialized anticolonial violence first comes into being. This new ideology of terrorism finds its counterpart in Victorian theorizations of the modern hegemonic state form, which justify the state’s monopoly of violence by imagining its apparatuses as specifically anti-terrorist. At the same time, Irish Fenian writings articulate anticolonial critique that anticipates the problematics of postcolonial studies and attempts to reimagine in generative and radical ways anticolonialism’s relation to modernity and the state form. By so doing, Alter-Nations argues for the centrality of Irish studies to postcolonial and Victorian studies, and reconceptualizes the boundaries and concerns of those fields.