foundation · 374 · Milan
Theodoret tells it plainly: Ambrose held the chief civil magistracy of the district and hurried to the church to quiet the factions, and the people cried with one voice, Make Ambrose our pastor — although up to this time he was still unbaptized. He was baptised and consecrated within about a week. What he did with it is the reason the see mattered for the next two decades: he refused to hand a basilica to the Arian court and sat in it with his congregation singing hymns he had written for the purpose until the troops withdrew, and after the massacre at Thessalonica he refused Theodosius communion until the emperor did public penance. This dataset already held Thessalonica and the council of Aquileia. It did not hold how he came to be there.
To stop a riot. The Nicene and Arian parties of Milan were contending over a successor to Auxentius and the governor went in to keep order.
A bishop who had been a catechumen an hour earlier, and the man who would make a Roman emperor do public penance.