Another Civil War
Within a few months of Valentinian’s death, Arbogast betrayed Theodosius by elevating Eugenius to the rank of Emperor in the West without the Eastern leader’s consent. Arbogast did this because he knew the Senate would be more receptive to a Roman than a Frank as a leader. Eugenius was connected with the Senate’s pagan aristocracy which was anathema to the Christian Theodosius. He bided his time before making moves against the new puppet ruler in the West.
Eventually, he made his anti-pagan laws even more severe by completely forbidding the worship of pagan gods on 8 November, 392. Two months later, he promoted his other son, Honorius, to the rank of Augustus as a clear indication that he would not tolerate any leader outside his family.
In spring 393, his enemies gathered in support of Eugenius in Italy, but Theodosius did not leave Constantinople until May 394. He left his sons behind and traveled with a large force comprised mainly of barbarians and their allies. Theodosius met Eugenius at the Battle of the Frigidus on 4 September, 394 in a fight to determine the fate of Christianity in the Western Roman Empire.
Both armies had 50,000 men in what became a two-day battle. Theodosius attacked without reconnaissance on day one and suffered heavy casualties. He received a welcome lucky break at the beginning of day two when a group of men picked by Arbogast to attack the emperor elected to desert to his side. Theodosius ordered another attack and was aided by a Bora wind which blew dust into the faces of Eugenius’ men, causing their lines to break. They were routed, and Eugenius was beheaded. Arbogast fled to the mountains but committed suicide when he realized that escape was impossible.
The Death of Theodosius & His Legacy
The Empire was briefly unified, but Emperor Theodosius became seriously ill, possibly as a result of his excursions against Eugenius. He died on 17 January 395 just four months after his success at the Frigidus. Upon his death, his army rapidly disintegrated as the Gothic contingent began raiding parts of the Empire and even made it as far as Constantinople. Neither the 18-year old Arcadius in the East nor 10-year old Honorius in the West proved capable of ruling and the decades after Theodosius’ death were marked by a slow decline and ultimately, a collapse of the Roman Empire in the West.
Theodosius is remembered for hiring large numbers of mercenaries into the Roman army and for being involved in two civil wars that depleted the Empire’s resources. He was the beneficiary of political intrigue and turmoil in the latter part of the Western Roman Empire but left completely inept heirs in charge. He simply wasn’t in complete control long enough to make a difference, and when he died, the Western Empire had little hope of surviving. His successor, Honorius, was utterly useless and did nothing as Rome was sacked in 410, for the first time since the aftermath of the Battle of the Allia in 390 BC.