Abstract Leonardo Bruni (1377–1444), chancellor of Florence, is today more famous as an initiator of civic humanism and a proponent of early modern republicanism than as a historian of medieval Florence. He owes this position most of all to Hans Baron, who argued that Florentine civic humanism—an exemplary mode of communal existence dedicated to the active life—as found particularly in Bruni's writings, stemmed from the resurgence of interest in antiquity, which pointed forward to a liberating, civilizing, and progressive modernity. Though James Hankins has recently argued that the dual theses of civic humanism and republicanism are mischaracterizations of the larger thrust of Italian Renaissance political thought, the scholarly literature overwhelmingly portrays Leonardo Bruni as incipiently modern and, by definition, un-medieval. But in emphasizing the role of antiquity in Bruni's “modern” thought, scholars have overlooked the importance of medieval history in the formulation and the content of Bruni's arguments. This article seeks to rectify this misappreciation by demonstrating how that quintessential medieval struggle, the conflict between popes and emperors, plays a central role in Bruni's political thought as it is found in the History of the Florentine People, written from 1415/16 to 1444.