by an elaborate religious ideology that assigned to the ruling emperors divine descent from Jupiter and Hercules, those gods that were most ostentatiously Roman in the traditional pantheon. The tetrarchy also insisted on renewed attention to the imperial cult – the worship of past, deified emperors and of the genius, or protecting spirit, of the living emperor. Both measures were designed to ensure that the gods would smile on and protect the empire. The famous Diocletianic persecution of Christians, widely known as ‘the Great Persecution’, was a consequence of this tetrarchic ideology, because Christians refused to worship any god but their own and by doing so might endanger the health of the state. If religion was one basis on which Diocletian rested his authority, he took other measures as well, reforming the currency, expanding the army, and re-enforcing the elite guard units that traveled with the emperor. Most importantly, he broke up the very large provinces of the early empire into more than a hundred smaller provinces, while also separating the military and civilian hierarchies in the imperial government. The first measure dramatically reduced the scale of any one official’s command, while the second meant that the officials who collected taxes and disbursed state salaries to the soldiers were not the same officials who commanded the troops in the field. Together, both measures undermined the ability of either military or civilian officials to claim the imperial throne for themselves. As we have said, the various Diocletianic reforms were ad hoc measures, meant to deal with the many different problems that had afflicted the third-century empire. Yet as a group, they were revolutionary: they not only allowed Diocletian to hold his throne for more than two decades, they also produced a system of government that remained effective even after the tetrarchy itself broke down. In other words, the type of imperial goverment originally outlined by Diocletian and the tetrarchy was in essence the same one with which Alaric had to deal a hundred years later. More important for our immediate purposes, however, Diocletian’s reforms meant that for the first time in over half a century, a Roman emperor was secure enough on his throne to deal effectively with barbarians beyond the northern frontier – with serious consequences for the Goths.
The Tetrarchs and the Northern Frontiers
This new imperial strength meant that the constant stream of frontier wars slackened considerably in the years before 305, when the augusti Diocletian and Maximian abdicated and passed the senior title on to their caesars Constantius and Galerius, who then appointed two new caesars to serve as their junior emperors. Instead of constantly reacting to events beyond their control, the tetrarchs were increasingly able to decide when and where they wanted to fight along their frontiers. They began to co-opt powerful barbarian leaders into imperial circles, and to manage the affairs of their barbarian neighbours in what they perceived as the best interests of Roman power. This policy can be inferred from obscure, but clearly very important, disturbances along the lower Danube in the 290s and early 300s. We saw in chapter one how Diocletian won a victory over one group of Goths, the Tervingi, as the panegyric of 291 attests. We do not know what prompted the campaign that led to that victory, but the decade that followed seems to have witnessed the substantial growth of Tervingian power. Although this Gothic expansion is not attested by positive evidence, it can be inferred from other known events, most importantly the displacement of an older barbarian grouping. Sometime before early 307, Galerius fought a campaign against the Sarmatians, which is to say in the region between the Danube and the Tisza rivers. Then, in the summer of 307, he attacked the Carpi further east, settling a very large number of them in a Roman province south of the Danube as defeated subjects of the empire.[54]
The willingness of the Carpi – virtually all of them, it seems