This introduction has two concerns. It outlines how urban citizens and professional soldiers have been relatively neglected by social historians of England, Scotland, Ireland, and the wider world and shows why both social groups should be taken much more seriously. It then traces the cultural antecedents which shaped idealizations of citizens and soldiers in Britain, Ireland and the wider world from the later sixteenth century. Recent accounts have positioned soldiers and citizens at opposing ends of the cultural spectrum: soldiering is seen as chivalric and neo-feudal, urban citizenship as an incubator for modern capitalist values. This article argues, in contrast, that “ancient” templates were crucial to modern constructions of both social types, contemporary theorists drawing on the same repertoire of classical and biblical learning to idealize citizen and soldier alike. The result was that citizens were encouraged to behave like soldiers and soldiers like citizens. In this way, the corporate practices of citizenship and soldiering were crucial conduits for the dissemination of Renaissance humanism across England, Ireland, Scotland, and the wider world.