The succession to Valentinian had fundamental political consequences for the nature of the Roman state. Already in 367, while suffering from a life-threatening illness, Valentinian had promoted Gratian, who had been born in 359, to the rank of Augustus. Gratian thus became the first of the so-called child emperors. He took up residence at Trier. On Valentinian's unexpected death in 375 Merobaudes and Equitius, the leading generals of the western armies, summoned the emperor's widow Justina, who had formerly been married to the usurper Magnentius, and her four-year-old son to Aquincum, where the latter, Valentinian II, was declared Augustus. Their objective was to prevent the appearance of a conspicuous power-vacuum in the most important military area of the empire, at a time when the western emperor Gratian was also still only sixteen years old. However, the manner of the promotion of a new child Augustus demonstrated with unambiguous clarity the power of the emperor's generalissimos, and their actions heralded an era when such men dominated the state in political as well as military matters.54 Valentinian and Valens are presented as imposing imperial figures, prone to anger and to abrupt and decisive judgments. However, this blustering exterior conceals genuine weaknesses. The new emperors lacked the dynastic authority of Constantine and his successors, and owed their position to the officers who had organized the succession to Jovian in 364. Army commanders and the holders of the great offices of state not only had key roles throughout this period in forming and executing policy, but also for arranging the composition of the imperial house. During the 370s and 380s the destinies of Gratian, Valentinian II, and Theodosius I, as well as that of the usurper Magnus Maximus, were decided not by the senior emperors at the time, but by cliques of dominant political and military figures. This was a new version of rule by an oligarchy, which had been Rome's fate for much of its history.55
In the eastern empire Valens was initially concerned with the frontier in Thrace. Three thousand Goths had come to Constantinople in 365 in support of Procopius, and despite their protests that they were merely honoring the treaty obligation owed to Constantine, Valens intended revenge.56 Valens carried out invasions of Gothic territory from his base in Lower Moesia at Marcianopolis. In 367 a fort was built at Daphne, a pontoon bridge was flung across the Danube, and troops scoured the lowlands, while the Goths took refuge in the mountains of the Serri (Carpathians).57 In 368 floods prevented invasion, but in 369 Valens crossed the river at Noviodunum, harried the tribe of the Greuthungi, and forced the Gothic leader Athanaric to flee for his life. The Goths sued for peace, “reduced to want by the interruption of their trade.” Valens' commanders tested the barbarians' good intentions, and a treaty was struck between Athanaric and Valens, who met on boats in mid-Danube, secured by an exchange of hostages. Athanaric was probably the grandson of Ariaricus who had made the Gothic treaty with Constantine in 332.
Two speeches by Themistius present a view of official policy towards the Goths.58 Oration 8, delivered on March 28, 368 in Marcianople, condemned earlier regimes for over-taxation and stressed the cost of foreign wars; oratio 10, delivered in Constantinople in early 370, explained and justified the peace deal:
And so the barbarian went away highly contented, in the grip of contrary emotions at once both confident and fearful, both contemptuous and wary of his subjects, cast down in spirit by those aspects of the treaty in which he had lost his case but exulting in those in which success had fallen to him.…Although the profit that comes from the give and take of business transactions was enjoyed by both races in common, Valens established only two of the cities which had been founded along the river as trading posts.…He built some completely new border forts and furnished others with what they required:– higher walls, water supply for forts, provision dumps, ports on the coastline, full complements of soldiers in the garrisons, armaments. (Themistius, Or. 10.135, trans. Moncur)
Valens had been unable to conquer the Goths; further campaigning was not cost-effective; and agreement broadly on Roman terms was the best solution. Goths were only allowed to do business at two crossing points on the river.
Hitherto tribute or subsidies had been paid to friendly Gothic chieftains, but this ceased with the new agreement, which echoed Valentinian's rebuttal of the Alemannic delegates to Milan in 365:59
No one saw gold coin counted out for the barbarians, countless talents of silver, ships freighted with fabrics or any of the things we were in the habit of tolerating before, enjoying the fruits of peace and quiet that was more burdensome than the incursions, and paying yearly tribute, which we were not ashamed to do, although we refused to call it by that name. (Themistius, Or. 10.135, trans. Moncur)
It is clear from the comparison with Valentinian's actions on the upper Danube, that the emperors were conducting a policy that had been agreed for both halves of the empire.
Foreign policy can be observed in other frontier areas.60 During the early 370s there had been trouble in the African province of Mauretania, when Firmus, the son of the pro-Roman king Nubel, organized a revolt provoked by anger at abusive Roman rule, and was even declared emperor. Like many of the Germanic tribal leaders he had served in Rome's forces.61 Between 368 and 371 there had been a growing dispute over control of Armenia, which almost escalated into a full-scale confrontation between Rome and Persia. However, Roman intervention was forestalled by the Gothic threat to Thrace which had emerged between 376 and 378, and the situation was defused by the death of the belligerent Sassanian king Sapor II in 379 (Ammianus 30.2).62 During the 380s three Sassanian rulers followed one another in rapid succession and were as preoccupied with internal security as their Roman counterparts. An agreement was reached based on a division of Armenia, into a smaller western zone, under Roman protectorate, and the east (Persarmenia) which looked towards Persia. Sapor III appears during this period to have allowed freedom of worship to the Christians in his empire, and this will have reinforced the entente with Rome. Relations between the two great powers were thus placed on a friendly footing which was only rarely disturbed before the beginning of the sixth century.63
A major new factor came to a head in 376; the encroachment of the Huns onto the main territory occupied by the Goths in the great river valleys of the Don, Dnieper, and Dniester. According to a fragment of Eunapius “the Scythians had been defeated and destroyed by the Huns and were being utterly extirpated. Those who were captured were massacred with their wives and children. There was no limit to the savagery employed in the killings” (Eunapius fr. 42.1). Their threat is made clear in a famous excursus of Ammianus (see p. 213), although the portrayal of these nomadic horsemen of east Asian origin owes much to classical stereotyping of barbarians, and in particular to Herodotus' famous account of the Scythians:
They have squat bodies, strong limbs, and thick necks, and are so prodigiously ugly and bent that they might be two-legged animals, or the figures crudely carved from stumps which are seen on the parapets of bridges.…They are totally ignorant of the difference between right and wrong, their speech is shifty and obscure, and they are under no constraint from religion or superstition.…this wild race, moving without encumbrances and consumed by savage passion to pillage the property of others, advanced robbing and slaughtering over the lands of their neighbours till they reached the Alans. (Ammianus 31.2, trans. Hamilton)
The Alans (earlier known as the Massagetae) were an Arian race from north of the Caucasus: “tall and handsome, with yellowish hair and frighteningly fierce eyes. They are active and nimble in the use of arms and in every way a match for the Huns, but less savage in their way of life” (Ammianus 31.2.21).
Ammianus' account of these movements of barbarian peoples beyond the Danube needs to be treated with caution. The Romans would have had access to little reliable information about the Huns and the Alans, and their main source would have been the Goths themselves, pleading to be allowed across the river into the empire. The Huns themselves had only a minor role to play in the events of the next twenty years, although it is significant that they were responsible for an invasion of Asia Minor in the mid-390s.64They only emerged as a sustained threat to Rome in the second quarter of the fifth century. By this period they had coalesced from nomadic groups of mounted raiders into a coherent political force, and their leaders occupied permanent settlements in the eastern part of modern Hungary.65 During the 370s it is more likely that they presented a high nuisance value, rather than an existential threat to the settled peoples between the Don and the Danube. Accordingly in searching for the reasons that led first the Gothic Tervingi, and then the Greuthungi to cross the Danube en masse in 376, we should probably lay much more stress than contemporary accounts do on the attractions of life in the Roman provinces to the barbarians, especially as economic conditions north of the Danube had probably worsened since the new frontier agreement reached in 369.
Admitting the Gothic tribes, although a historical inevitability with countless precedents in Roman frontier policy,66 proved catastrophic in the short term. The official agreement to allow the Tervingi into the empire was sullied by serious abuses on the Roman side which alienated the newcomers. Meanwhile the Tervingi, commanded by Fritigern, were joined by the Greuthungi, who had crossed the Danube against Roman wishes (see p. 311). Eunapius (fr. 42) suggests that 200,000 fugitives were introduced into Thrace in this way. They were reinforced by other groups of Goths who were already in service as part of the Roman army and were quartered at Adrianople in Thrace. Summary orders for transfer to Asia and mistreatment at the hands of the civilian magistrates at Adrianople drove these Gothic auxiliaries to rebel and join their fellow countrymen. There were skirmishes and a major encounter at the battle of Ad Salices (north of Marcianopolis) in 377. Valens himself came to Constantinople, and then advanced to Adrianople. Hindsight suggests that he should have waited for reinforcements from the western emperor Gratian, but he miscalculated Gothic strength and ventured battle on his own. He and perhaps 10,000 Roman troops lost their lives at Adrianople. According to Ammianus this was the biggest military setback for Roman troops since Cannae, and the emperor's body was never recovered. The Goths, although they failed to capture Adrianople and Constantinople, occupied Thrace and Illyricum blocking communications with the West (Zosimus 4.24.3). The death of Valens marked the end of an epoch. This was virtually the last occasion on which a Roman emperor led his troops into a major encounter until Heraclius' campaigns in the seventh century.