ABSTRACT
This chapter examines Diocletian's administrative, financial, and military reforms; continuing reconfigurations of the army and its size and increasing barbarization; the settlement of barbarians in the western empire; and the key episodes of the fourth century: the ascendancy and reign of Constantine the Great; the extraordinary brief reign of Julian; the split of western and eastern responsibilities under Valentinian and Valens; and events leading up to the Battle of Adrianople, and its aftermath, referenced above by Libanius. Given the security threat posed by Rome's belligerents on the frontiers, it is logical to examine the military reforms of Diocletian in the first instance, before the important administrative and economic changes are considered. It is insightful to look at the complexion and movements of Rome's key belligerents in this period, notably the Franks, Sarmatians, and Goths; and also the Huns who forced the first wave of migrations into the Roman empire.
