9 THE DIVISION OF THE EMPIRE

The centre of gravity of the empire was now moving away from Italy and Rome. It was no longer possible to govern it as a single unit. In 284 Diocletian became emperor and undertook a reorganisation of the imperial government.

This administrative structure marks the beginning of the process of partition of the empire, with each part having its own emperor. In the early fourth century Constantine built a new capital for the east at Byzantium, or Constantinople, while the western imperial government was based in Milan. Theoretically, however, although the relations of the two parts were sometimes hostile, the empire was still considered to be a single whole, of which the emperors were joint rulers. They struggled to maintain the frontiers of the empire along the Rhine-Danube line, in the face of repeated incursions from Germanic tribes. The latter were themselves being pressed by a general movement westward of other tribes, particularly the dreaded Huns. The defence of the frontier required an army of about half a million men and friendly tribes were allowed by treaty to settle within the empire as foederati, on the under­standing that they helped to defend it. Large land-owners were obligated to supply soldiers from their estates or else to pay for others to be recruited elsewhere. As a result, many so-called barbarians were recruited into the Roman army and some rose to high command.

The Greek speakers of the eastern empire, which had been less affected by barbarian infiltration than the western empire, now began to think of themselves as the prime upholders of the Roman traditions. They called themselves Rhomaioi and Constantinople was known as New Rome. In the later fourth century, however, they too began to feel the pressure from the barbarians. In 376 the Visigoths entered Thrace and defeated the eastern imperial army at Adrianople, only 220 km from Constantinople. The situation was restored by the last great campaign­ing emperor, Theodosius I, but at the cost of the ‘barbarisation' of the eastern army. By an unprecedented treaty in 382 he allowed the Visigoths to settle south of the Danube as a self-governing tribe, with their tribal organisation intact and under their own laws.

On the death of Theodosius in 395, a formal division was created between the two parts of the empire. It was based on the equalisation of resources. Italy, Africa, Gaul, Spain and Britain were clearly in the western part and Thrace, Asia Minor, Oriens and Egypt clearly in the eastern part. The central prefecture of Illyrium was divided between the two: Pannonia (south and west of the Danube in modern Austria and Hungary) was assigned to the west, while Dacia (modern Romania) and Macedonia went to the east. The frontier started at the confluence of the rivers Sava and Danube near Singidunum (modern Belgrade), then went south along the river Drina to the Adriatic and then continued over the Mediterranean to separate Africa from Egypt.

As Edward Gibbon says, ‘the respective advantages of territory, riches, populousness and military strength were fairly balanced and compensated in this final and permanent division of the Roman empire' (Decline and Fall, ch. 29). This severance of the mainly Greek-speaking east from the Latin west was to have momentous consequences in later centuries.

Theodosius's reign also marks the conclusion of another transforma­tion of the empire which began with Constantine, namely its Christianisation. Constantine's Edict of Milan of 313 had ended the official persecution of Christians. Impatient with theological niceties, Constantine made great efforts to unite Christianity, by dealing with the Donatist schism and the Arian heresy, culminating in the Council of Nicaea in 325. Nevertheless the old Roman cults continued at Rome and, until the time of Theodosius, the western emperors accepted the office of pnntifex maximus. Theodosius, a committed adherent of ortho­dox catholicism, was much stricter than his predecessors in eliminating paganism and in making catholicism rather than merely Christian belief the official religion. The fact that the Visigoths were staunch Arians compounded his problems in dealing with them.

The new religion hardly affected the supremacy of the emperor ini­tially, since he held himself to be the minister of God for the good of men, but courageous bishops asserted their spiritual power. After Theodosius had ordered the massacre of the citizens of Thessalonica, for lynching the garrison commander, St Ambrose in Milan refused him communion until he had publicly done penance in the cathedral, which he did. Christianity seemed to have little effect, however, on private law. Legislation conflicting with its practice, such as a law of Augustus which penalised celibates in order to increase the birth-rate among citizens, was repealed. But in general the private law of pagan times needed little amendment to fit it for a Christian empire.