By Gregory S. Aldrete, Ph.D., University of Wisconsin, Green Bay
After the death of Julian the Apostate in 363 AD, power in the Roman Empire again fell into the hands of the military, who selected the next several emperors. Some of these generals were pagan barbarians who came into conflict with the Christian Emperors.

Eastern and Western Roman Emperors
The military tended to elevate pairs of men, with one serving as the eastern emperor and the other acting as western emperor. In the years leading up to the Battle of Adrianople in 378, the pair were Valentinian in the west, and Valens in the east. Valentinian, the senior, had managed to stay in power for quite a while, ruling since 364 AD and successfully fending off a number of crises.
Unfortunately for Valentinian, he was well-known to possess a particularly explosive temper, and this proved his undoing. In 375 AD, when he was meeting with some envoys of the central European Quadi tribe, they tried to excuse their recent raiding activities by claiming that they had been provoked by the construction of a new Roman fort. Upon hearing this, Valentinian flew into a towering rage. Ammianus describes what happened next:
Boiling with fury, he railed against them in noisy and abusive language, accusing the whole tribe of ingratitude and forgetfulness of past favors, when suddenly, as if struck by lightning, his breathing and speech became obstructed, a fiery flush spread over his face, his pulse failed, and he was drenched in a deadly sweat.
Apparently, Valentinian became so incensed that he suffered a paralytic stroke and died later that night. His replacement was Gratian, the man whom Valens was unwilling to share credit with, leading to his own death at Adrianople. Valens was succeeded by Theodosius, who would rule until 395 AD.
This is a transcript from the video series The Roman Empire: From Augustus to the Fall of Rome. Watch it now, Wondrium.
Pagan Versus Christian Emperors
All of these emperors after Julian were Christian, but for the most part they had been fairly tolerant of paganism, and had not banned traditional forms of worship. There were still many pagans in the empire, and an interesting moment of conflict arose during the rule of Theodosius.
Settling on who should be Theodosius’ co-emperor for the Western Empire sparked a complicated series of struggles among different contenders. Eventually, the dominant figure who emerged was a Frankish general named Arbogast. By this point, it was common for barbarians to serve in Rome’s armies, and Arbogast is an example of how far such men could rise.

Due to his barbarian origins, however, he would have had trouble being accepted as an official emperor. So he put forward a man named Eugenius to serve as a figurehead, while he would act as the power behind the throne. Arbogast and Eugenius seem to have contemplated reviving paganism, and as a result came into conflict with Theodosius.
The ensuing Battle of the Frigidus River in 394 AD has sometimes been portrayed as a struggle between Christianity and paganism for control of the Roman Empire. This may be an oversimplification, but Theodosius won the battle, and has gone down in Church histories as Theodosius ‘The Great’ because he then officially banned pagan worship. From then on, Christianity would be the unchallenged official religion of the empire.
Learn more about how Julian the Apostate tried to reinstate the Olympian gods.
Powerful Women and Barbarian Generals
In the decades following the death of Theodosius in 395 AD, most of the emperors were drawn from the ranks of his sons, grandsons, and nephews. But many of these were still just children and, as it had under the Severans, the empire witnessed a period when real power resided in the hands of a sequence of powerful women.
These women were related by blood and marriage to the powerful, who manipulated events through their children, brothers, or husbands. This able group of women, under whose supervision the empire continued in a reasonably prosperous manner, included Galla Placidia, Eudoxia, and Pulcheria.
The other major development during this time was the growing prominence of generals, such as Arbogast, who had barbarian origins. After his defeat at the Frigidus River, Arbogast had committed suicide, but another man with a similar background would play a central role in politics during this time.
This was Stilicho, who was the son of the union between a Roman woman and a Vandal serving as an officer in the Roman army. Stilicho had pursued a military career and had risen to become one of Theodosius’s most dependable generals, eventually marrying one of the emperor’s nieces. Upon Theodosius’s death, he had even been appointed guardian to the late emperor’s two young sons Honorius and Arcadius.
Learn more about Augustus, the first emperor.
Internal Power Struggles in the Roman Empire

This was an era of intense political infighting and maneuvering among the many factions vying for power within the empire. The different factions included the powerful women of the imperial family, the actual emperors, Stilicho and the generals, other army officers, the Praetorian Prefects, and members of the imperial bureaucracy.
Not infrequently, barbarian tribes and leaders would be recruited by one faction or another, given Roman titles and privileges, and then employed in civil wars. There was also a growing tendency for the eastern and western halves of the empire to turn inward and focus on their own problems, failing to cooperate when common threats appeared, and refusing to support one another.
All of this was complicated even further by continued external pressure from barbarian tribes on the frontiers and economic crises within the empire.
Common Questions about Power Struggles in the Roman Empire
Valens and Valentinian were the Emperors of Eastern and Western Roman Empires, respectively, in the years before the Battle of Adrianople.
Arbogast was a Frankish general in the Roman army, who emerged as a contender for becoming the Western Roman Emperor, when Theodosius was the Eastern Roman Emperor.
The Battle of the Frigidus River was caused by an attempt to revive paganism by general Arbogast and his figurehead, Eastern Emperor Eugenius. This brought them into conflict with Theodosius, who defeated them at the Frigidus River and finally established Christianity as the official state religion of the Roman Empire.
After the death of Theodosius, came an era of intense political infighting and maneuvering among the many factions vying for power within the Roman Empire. The different factions included the powerful women of the imperial family, the actual emperors, Stilicho and the generals, other army officers, the Praetorian Prefects, and members of the imperial bureaucracy.