His father, likewise named Ambrosius, was prefect of the Gauls, an office the jurisdiction of which extended over Spain, Britain, Cis- and Trans-Alpine Gaul. His chief official residence was Trèves, where probably St. Ambrose was born, as seems most likely, a.d. 340. The exact date depends upon whether the passage “barbaracis motibus et bellorum procellis,” etc., Ep. lix., 12–3, refers to the war against Maximus, a.d. 387, or to that against Eugenius, a.d. 393–4; so that the birth year of St. Ambrose might be 333 or 340. The latter date is, however, most generally accepted.