Arbogast (magister militum)
Zosimus, without ascribing a familial relationship, says Arbogast and Bauto were both "Franks by birth, exceedingly well-disposed to the Romans, completely immune to bribes, and outstanding as regards to warfare in brain and brawn".
The combined western and eastern armies defeated the Gothic leader Fritigern, pushing his forces out of Macedonia and Thessaly towards Thrace in lower Moesia where the raids had begun, and ultimately aided the establishment of a peace treaty with the Goths in 382.
In the following year, a Roman officer in Britain named Magnus Maximus was proclaimed emperor by his soldiers, and quickly moved to the continent to challenge Gratian's control of the western provinces.
His death allowed Valentinian II to undergo a second, real accession as emperor, establishing control over the Italian peninsula, while Maximus held onto Gaul and Britain in an unofficial armistice.
[9] It is also important to acknowledge that no ancient sources ever give Arbogast a specific title; because he was clearly the dominant military commander in the west for much of his career, he is assumed to have been magister militum, the highest rank in the Roman army.
In 387, when Maximus finally broke the peace by invading Italy, Valentinian fled with his family, courtiers, and generals to Thessalonica on the very edge of western territory, where he pleaded with Theodosius I for assistance.
And so he came to great power, such that even in the Emperor's presence he spoke quite freely, and he vetoed those actions which he thought were wrong or unbecoming...for Arbogastes was supported by the good will of all the soldiers.
[24] Ambrose claims that the death of Valentinian II was the result of a dispute with Arbogast, involving diplomacy and who would lead the armies defending Italy from Balkan invasions.
[37] With the new ruler established, in 393 Arbogast travelled across the Rhine frontier to take revenge against his own Franks and their kinglets Sunno and Marcomer, who had plundered the region in the reign of Valentinian.
[38] The campaign, which met little opposition, included restoration of the fortress city of Cologne, an important strategic location which allowed the Romans to occupy the Rhine's eastern bank for the last time in their history.
[36] Eugenius was a Christian, whose religious position had been approved by Ambrose and Theodosius I, but he was sympathetic to paganism and allowed the reopening of temples closed under Gratian and Valentinian II.
Furthermore, all communication between the Eastern and Western courts was now managed by Rufinus, Theodosius' new Praetorian Prefect, who could poison the Emperor's mind against Arbogast and Eugenius if he wished.
[43] In order to shore up their legitimacy, Arbogast and Eugenius moved in April 393 to take control of Italy, a strategic and symbolic center of the Roman world.
The forces of Arbogast and Eugenius entrenched themselves in a plain with their backs turned to the river Frigidus, with additional troops occupying nearby elevated positions and the south still defended against outflanking movements.
The ambush was thwarted by a local weather phenomenon known as the bora, wherein the pressure effect on cold air passing over the mountains produces cyclonic winds of up to 60 mph.
[49][50][51] Christian writers such as Theodoretus and Saint Augustine say that the Battle of the Frigidus was won through divine intervention, although a modern scholar sees more significance in Theodosius' unprecedentedly large-scale employment of barbarian mercenaries.
[54] Gerard Friell and Stephen Williams concur, summarizing Arbogast as "a first-class military commander with a fine record, very popular with the army and wholly loyal to the houses of Valentinian and Theodosius".
Thus, in Christopher Bendle's estimation, Arbogast ascended not through military prowess but through a gift for manipulating personal relationships and winning the loyalty of his subordinates and peers.
[55] The sources make it clear he was deeply popular with the army, the most powerful institution of the later Roman Empire, and multiple emperors trusted him with positions of authority.
