ABSTRACT
This chapter discusses the gradual division of the empire into western and eastern halves. In the west, the heavy casualties endured by the western comitatus at Mursa (351) and the Frigidus (394), combined with sustained pressure on the Rhine and Danube, and then invasion and settlement, left the imperial court in Ravenna unable to project its authority. Constant warfare and the settlement of groups from Barbaricum steadily deprived the western authorities of the tax base, leaving them unable to fund the government. In this climate, to which the Hunnic migration of the fourth century contributed, the Visigoths were settled in Aquitania; the Vandals, Alans, and Suebi invaded Gaul and settled in Spain, before the Vandals moved to capture the African provinces, and a succession of weak emperors, dominated by powerful warlords and courtiers, lacked the means to correct the situation. The Hunnic migration also helped lead to the catastrophic defeat of the eastern comitatus by the Tervingi and their allies at Adrianople (378), which led in turn to the settlement of the Visigoths inside the empire. The Huns under Rua, Bleda, and Attila were able to extort the eastern court for money and privileges before they finally were defeated by Aëtius in 451. Problems on the Persian front saw Constantius II lose Amida in 359, while Nisibis was besieged on several occasions. Calamity arrived in 363 when Julian was killed on campaign and his successor Jovian ceded Nisibis, Singara, and other Mesopotamian territories to Shapur II. Tensions in Armenia and other territories in the Caucasus (Lazica, Iberia, Persarmenia) also caused friction, but there were also moments of cooperation between Arcadius and Theodosius II and Yazdegerd I. On the religious front, bishops became stronger vis-à-vis the imperial court: this is most clearly seen with Ambrose, bishop of Mediolanum (Milan), and the last vestiges of pagan Rome began to vanish under legislation passed by Gratian and Theodosius I; much of the empire’s evolving Christian character is also reflected in the Theodosian Code. Several important councils, including Ephesus (431 & 449) and Chalcedon (451), attempted to regulate orthodoxy and heresy, but caused major disruption within the higher ranks of the church.
