 Valentinian was born in the western capital of Ravenna, the only son of Galla Placidia and Flavius Constantius.His mother was the younger half-sister of the western emperor Honorius, while his father was at the time a patrician and the power behind the throne.Through his mother, Valentinian was a descendant both of Theodosius I, who was his maternal grandfather, and of Valentinian I, who was the father of his maternal grandmother.