A.D. 381 heretics, pagans, and the dawn of the monotheistic state ( PDFDrive )

Arcadius the status of an Augustus without even referring the matter to Gratian.
From then on things went downhill for Gratian. In the summer of 383 the
commander of the British legions, Magnus Maximus, revolted and crossed over
the Channel to Gaul, and when Gratian marched north to confront him he found
his army melting away. Left isolated in a province that offered him no support,
he was killed by an officer who had defected to Maximus.
Gratian’s death left the twelve-year-old Valentinian II as sole legitimate
emperor in the west, but there was little the boy could do against Maximus, who
now held power in Gaul and who proclaimed himself to be a Nicene, possibly in
the hope of attracting Theodosius’ support for his usurpation. Maximus offered
to take Valentinian under his wing, but the young emperor was sufficiently well
established in Italy, with a court of Italian aristocrats whose status depended on
his continued rule, to be able to refuse. Although the details of any agreement
are lost, both rulers appear to have recognised each other’s position and the right
to control their own territories without the interference of the other. Theodosius
too accepted that he could do little to confront Maximus. They had, in fact, once
served together in the elder Theodosius’ army in Britain.
Valentinian received strong support from his mother Justina, the widow of
Valentinian I, who appears to have had much of her late husband’s tenacity. Both
she and her son were Homoians, and they had built up a body of supportive
clergy in Milan headed by an ‘alternative’ bishop, who had taken the name of
Ambrose’s Homoian predecessor, Auxentius. Their retinue also included Gothic
troops who, like all the Germanic tribes, were subordinationists. The scene was
set for a power struggle between the Nicene Ambrose and the Homoian court.
Once again Ambrose was to show his opportunism and genius for
manipulation of a public event in his favour. The first conflict arose over the
Altar of Victory in the Senate in Rome. A group of pagan senators, led by the
city’s prefect, Symmachus, took advantage of the change of emperor to formally
request Valentinian for a restitution of all pagan privileges to Rome, including
the return of the altar to the Senate. Symmachus was a consummate tactician,
and rather than attempting to confront Christianity on behalf of the ancient pagan
beliefs of the capital, he portrayed the issue as one of tolerance. Echoing the
arguments of Porphyry and Themistius, he pleaded for the recognition of
diversity of worship: ‘The divine Mind has distributed different guardians and
different cults to different cities. As souls are given separately to infants as they
are born, so to peoples the genius of their destiny... If a long period gives
authority to religious customs, we ought to keep faith with so many centuries,