Career
Rise to power
The choice of Eugenius, over proclaiming himself, offered to Arbogast two strong advantages: first, Eugenius, a Roman, was more suitable than Arbogast, a Frank, as an emperor. Furthermore, the Roman Senate would have been more likely to have supported Eugenius than Arbogast. Civil, religious, and military policies
After being installed as Emperor, Eugenius changed the imperial administrators.
Eugenius replaced these administrators with others loyal to himself, coming from the senatorial class.
Eugenius was nominally a Christian, and therefore was reluctant to accept a program of imperial support to Polytheism. This religious policy created tension with Theodosius and the powerful and influential Bishop Ambrose, who left his see in Milan when the imperial court of Eugenius arrived.
Eugenius was also successful in the military field, notably in the renovation of old alliances with Alamanni and Franks. Arbogast, who was a Frank and had also Alamanni and Frankish soldiers in his ranks, marched to the Rhine frontier, where he impressed and pacified the Germanic tribes by parading his army in front of them.
Fall
When he was elected emperor, Eugenius sent ambassadors to Theodosius"s court, asking for recognition of his election.
Theodosius received them, but started to gather troops to defeat Eugenius. Theodosius also promoted his eight-year-old son Honorius to the rank of "Augustus" of the West in January 393. Theodosius then moved from Constantinople with his army, and met Eugenius and Arbogast in the Battle of the Frigidus (Vipava Valley, Slovenia) on 6 September 394.
Arbogast immediately committed suicide after the defeat, while Eugenius was held for execution as a criminal, his head afterward being displayed in Theodosius" camp.
The reign of Eugenius marked the end of an era and the beginning of a new one. This had happened many times before in the previous two centuries, but this time it was to be final – the Roman Empire never reunited, even under Leo I the Thracian (when there was no Western Emperor for some periods), and soon after his reign, the western half fell.
The Battle of the Frigidus was part of a trend towards using increasing percentages of barbarian troops, especially in the west, where it led to the weakening of the Empire itself.
