ABSTRACT
When Diocletian and Constantine rebuilt the structure of the Empire shattered by the events of the third century they were faced with many problems that had not existed during the Principate (Rostovtzeff, 1957; Cook, Adcock et al., 1939; Walser and Pekáry, 1962; Alföldy, 1979, 139–64). The Empire was now under more or less continuous attack, often at more than one frontier at a time. The needs of defence impelled the government to make much greater and inevitably more unpopular demands on the manpower and resources of the Empire than ever before. At the same time it had lost cohesion. The army, once the great romanizer, had become regionalized, and the soldiers' concern for their native province, and often their attachment to particular generals had become stronger than their loyalty to the Empire as a whole. The economic ties linking frontier areas with the central provinces had grown weaker as the provinces had become self-sufficient in many of the items that they had previously imported from Mediterranean areas. There was thus less need for traders and shippers. The need had been further reduced by the fact that armies and civil servants had come to be paid in produce, raised and distributed by compulsory transport duties (MacMullen, 1976, 173ff.; Hopkins, 1980, 106 and 123–5). As the economy had become more localized the Roman way of life had lost some of its appeal. Even under the most favourable conditions romanization ceased to advance; in the north-western provinces it went into retreat.
