other · 356–360 · Poitiers
Constantius wanted the Western bishops to subscribe against Athanasius and Hilary would not, so he was banished to Phrygia in 356. The exile was meant as a silencing and worked as an education: he learned the Eastern debate from inside it, discovered that many of the people the West was calling heretics were arguing about words rather than substance, and wrote the twelve books On the Trinity while he was there. He also wrote On the Councils, explaining the Eastern formulas to Latin readers sympathetically enough that some of his own side thought he had gone soft. He was sent home in 360 — the sources suggest because the Eastern bishops found him more trouble present than absent — and spent his last years arguing the same case in Gaul. Jerome called him the Rhone of Latin eloquence. The comparison with Athanasius, which is old, is about the exile as much as the theology.
To get an inconvenient Gallic bishop out of the West without making a martyr of him.
Four years inside the Greek argument, and the first Latin theologian who could actually explain it to the West.