The Ecclesiastical History of Socrates Scholasticus

Nearly at the same time with the holding of these Synods at Constantinople, the following events occurred in the Western parts. Maximus, from the island of Britain, rebelled against the Roman empire, and attacked Gratian, who was then wearied and exhausted in a war with the Alemanni. In Italy, Valentinian being still a minor, Probus, a man of consular dignity, had the chief administration of affairs, and was at that time prefect of the Prætorium. Justina, the mother of the young prince, who entertained Arian sentiments, as long as her husband lived had been unable to molest the Homoousians; but going to Milan while her son was still young, she manifested great hostility to Ambrose the bishop, and commanded that he should be banished. While the people from their excessive attachment to Ambrose, were offering resistance to those who were charged with taking him into exile, intelligence was brought that Gratian had been assassinated by the treachery of the usurper Maximus. In fact Andragathius, a general under Maximus, having concealed himself in a litter resembling a couch, which was carried by mules, ordered his guards to spread a report before him that the litter contained the Emperor Gratian’s wife. They met the emperor near the city of Lyons in France just as he had crossed the river: who believing it to be his wife, and not suspecting any treachery, fell into the hands of his enemy as a blind man into the ditch; for Andragathius, suddenly springing forth from the litter, slew him. Gratian thus perished in the consulate of Merogaudes and Saturninus, in the twenty-fourth year of his age, and the fifteenth of his reign. When this happened the Empress Justina’s indignation against Ambrose was repressed. Afterwards Valentinian most unwillingly, but constrained by the necessity of the time, admitted Maximus as his colleague in the empire. Probus alarmed at the power of Maximus, resolved to retreat into the regions of the East: leaving Italy therefore, he proceeded to Illyricum, and fixed his residence at Thessalonica a city of Macedonia.