Lewis William. Political networks, imperial relations, and the division of the Roman Empire, AD 337 to 350

Cardiff University, 2019. — 262 p.This thesis argues that the years AD 337 to 350 gave rise to a series of events that prompted one of the earliest and most influential territorial divisions of the Later Roman Empire. Following the death of Constantine the Great, his sons, Constantine II, Constantius II, and Constans, arranged to share power. But a failure of imperial collegiality, culminating in the civil war of 340, led to the empire being divided into autonomous and sovereign states. Following the period of the Tetrarchy, this established a new precedent for how the empire was governed, which eventually became permanent in 395 after the death of Theodosius I. The importance of this first division has been overlooked in scholarship, and this thesis will establish when, how, and why the Roman Empire was divided by the sons of Constantine. This thesis is arranged in the following way. Chapter 1 introduces the thesis, provides an overview of scholarship and the available evidence, establishes a definition of division, and summarises the structure of the thesis. Chapter 2 examines the succession arrangements of Constantine and how they were overturned by Constantius, before considering the negotiations between the sons and their acclamation as Augusti. Chapter 3 reconstructs the governance of the empire from 337 to 340, and demonstrates that there was still a functional imperial hierarchy and undivided empire, even though the authority of Constantine II was beginning to be eroded. Chapter 4 re-examines the conflict between Constantine II and Constans in 340, and argues that the accepted narrative of Constantine II’s aggression is false, and that Constantine II was ambushed on the initiative of Constans. This fatally undermined imperial collegiality and hierarchy, which resulted of the de facto division of the empire between the surviving brothers, Constantius and Constans. Chapter 5 uses prosopography to examine how the newly divided empire functioned, focusing on the praetorian prefecture, the consulship, and the relationship between imperial courts. Chapter 6 looks at the assassination of Constans and its aftermath, which demonstrates how division had become an established part of the imperial administration, and it was only the efforts of Constantius that caused its temporary reunification.Chapter 7 considers Constantius’ attempts to preserve unity in the 350s, and his ultimate failure to address the expectation of division among the army and administration. This chapter concludes the thesis by showing that the division of the Roman Empire from 340 to 350 had become too entrenched to be reversed, and that the precedent established in these years led to the permanent division of the Roman Empire.