VALENTINIANO III (Flavius Valentinianus Augustus), ROMAN EMPEROR OF THE WEST. — Son of Flavius Constantius and Galla Placidia, sister of the emperor Honorius, born in 419, died in Rome on 16 March 545.
At the death of his uncle Honorius (423), the Byzantine court, where Placidia had taken refuge with her son, sent V. John; John was defeated, and V. was able to be crowned in Rome (425). He established his residence at Ravenna and, given his tender age, effective government lay in the hands of his mother. Placidia gave great impetus to the arts by embellishing the city with splendid monuments, and benefited from the vigorous and brilliant work of the general Aetius in keeping at bay the barbarians pressing into Gaul and Spain. In 429 the Vandals landed in Africa, and, despite the agreement of 435, a few years later (439) they were masters of those regions and threatened Italy itself. In 451 Attila invaded Gaul but was defeated by Aetius at the Catalaunian Fields near Châlons; he came to Italy the following year, and V. Rome, whence he sent an embassy to the barbarian, which included Pope St. Leo: Attila, who had already occupied and destroyed several cities, unexpectedly withdrew. Meanwhile in Rome, after the death of his mother (450), V., left as the sole arbiter of the government, showed himself dissolute and inept, making enemies of everyone, especially the nobles, whose honor he offended. A conspiracy led by Petronius Maximus, also to avenge the death of Aetius (September 454), eliminated him while he was on the Via Labicana.
V.’s religious policy was directed toward ever more vigorously repressing paganism, safeguarding the Catholic faith, and combating heretics. In 451 he prohibited, under penalty of death and confiscation of property, the reopening of temples that had already been closed or the performance of sacrifices (Cod. Iustin., I, 11, 7). Together with his mother and wife, he wrote to Theodosius II urging proceedings against Eutyches (PL 54, 858 ff.), and in 452 decreed that the memory of Patriarch Flavian be rehabilitated (Cod. Iustin., I, 3, 23); in 451 he confirmed all the privileges granted to the Catholic Church and abrogated contrary decrees (ibid., I, 2, 12). He published decrees against heretics, and especially against the Nestorians, in 428 and 435 (ibid., I, 1, 3; I, 5, 6); in 445 he issued a constitution against the Manichaeans, by which they were declared enemies of the State, their expulsion from the cities was ordered, they were forbidden access to civil and military offices, and were deprived of every civil right (PL 54, 622–24).