Valentinian II (Flavius), son of Valentinian I and Justina, was proclaimed Augustus after his father's death in AD 375, when about five or six years of age.
His elder brother being Gratian, then about sixteen, and the two brothers divided the West between them: Valentinian II taking Italy, Illyricum, ad Africa and Gratian Gaul, Spain, and Britain; but as the former was so young the latter was really the sovereign of the West. The year after the death of Valens, in AD 379, Gratian appointed Theodosius I to scceed him, and in AD 383 was killed by Magnus Maximus. In AD 388 Theodosius I defeated and killed Magnus Maximus, who had driven Valentinian II out of Italy, and reinstated the latter as sole emperor of the West. Valentinian II leaving too much power in the hands of Arbogastes, commander of the Roman forces in Gaul, and attempting, when too late, to deprive him of command, was strangled by order of Arbogastes in AD 392.