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

borders, which ran along the rivers Rhine and Danube, vital communication
routes as well as boundaries, there was a mass of Germanic tribes whose internal
tensions, shifting allegiances and hunger for resources coalesced in opportunistic
raids on the empire. On their own these war bands were hardly a match for a
Roman legion, but the border was long and often difficult to defend and raiders
could strike deep into the empire before they were driven out. In the east, the
Persian empire was a more stable opponent, but when wars broke out they
tended to be major conflicts, with cities and large stretches of territory changing
hands. In 363, the Persians gained an advantage when the Roman emperor
Jovian’s armies were trapped in Persian territory and he was forced into a
humiliating peace treaty in which control over border provinces was surrendered
by the Romans. 2
Jovian died in 364, less than a year after his defeat, and, as often happened at
times of crisis, his army declared one of its well-tested generals, Valentinian, as
the new emperor. It was to prove a good choice. Valentinian had his dark side - a
terrible temper and a propensity to deal brutally with subordinates - but he was
effective. Revolts in Britain and North Africa were suppressed and Valentinian
swept far into German territory, devastating the forest strongholds of the local
tribes. Back on the Rhine and Danube borders he rebuilt forts and strengthened
defences.
On Valentinian’s elevation the army insisted that he appoint a co-emperor.
Anxious to put in place an imperial dynasty, he delegated power over the eastern
Greek-speaking provinces of the empire to his brother Valens. (The boundary
was drawn so that, apart from Thrace, the whole of Europe remained under
Valentinian.) There would have been better choices. Valens ruled conscientiously
but he had none of the military flair of his brother. The historian Ammianus
Marcellinus, one of the major sources for the period, describes Valens as ‘better
at choosing between different options than devising them’ - a competent man but
not one of initiative. 3 Like his brother, he campaigned across the northern
border, among the Goths, a Germanic people settled north of the Danube and
around the Black Sea, but any major victory eluded him. When eventually he
signed a peace treaty with the Goths in 369, he trumpeted it as a success,
awarding himself the title of Gothicus Maximus, but if he had been stronger he
would have imposed clauses allowing him to recruit from the Goths the men he
desperately needed to keep up his forces.
In 375 there was a fresh challenge to Valens from the Persian Empire. The