This book presents a new history of the leadership, organization, and disposition of the field armies of the east Roman empire between Julian (361–363) and Herakleios (610–641). To date, scholars studying this topic have privileged a poorly understood document, the Notitia dignitatum, and imposed it on the entire period from 395 to 630. This study, by contrast, gathers all of the available narrative, legal, papyrological, and epigraphic evidence to demonstrate empirically that the Notitia system emerged only in the 440s and that it was already mutating by the late fifth century before being fundamentally reformed during Justinian's wars of reconquest. This realization calls for a new, revised history of the eastern armies. Every facet of military policy must be reassessed, often with broad implications for the period. The volume provides a new military narrative for the period 361–630 and appendices revising the prosopography of high-ranking generals and arguing for a later Notitia. ‘This is a well-written and stimulating book that compels readers to reassess what they know or believe about the military administration and defensive capabilities of the east Roman empire. The appendices provide valuable correctives to the prosopography of military personnel.’ Philip Rance, Bryn Mawr Classical Review A new narrative history of the east Roman field armies based on all the available sources. Anthony Kaldellis is Professor of Classics at the University of Chicago. He has written on many aspects of Byzantine history, literature, and culture, including the reception of the classical tradition, identities (Romanland, 2019), monuments (The Christian Parthenon, Cambridge University Press, 2009), and politics (The Byzantine Republic, 2015). He has completed a new history of Byzantium (The New Roman Empire, forthcoming) and is the host of the popular podcast Byzantium & Friends. MARION KRUSE is an Associate Professor of Classics at the University of Cincinnati. His research focuses on Roman and Byzantine history and historiography, and he has published on topics ranging from Prokopios' Wars of Justinian to the prosopography of the eleventh century. His first book, The Politics of Roman Memory (2019), examines the role of memory in eastern Roman responses to the fall of the western empire, especially in the Novels of Justinian.