Valentiniānus in Harpers Dictionary of Classical Antiquities

Roman emperor A.D. 426-455, was born 419, and was the son of Constantius III. by Placidia, the sister of Honorius and the daughter of Theodosius I. He was declared Augustus in 425 by Theodosius II., and was placed over the West, but as he was only six years of age the government was intrusted to his mother Placidia. During his long reign the Empire was repeatedly exposed to the invasions of the barbarians; and it was only the military abilities of Aetius which saved the Empire from ruin. In 429 the Vandals under Genseric crossed over into Africa, which they conquered, and of which they continued in possession till the reign of Justinian. The weakness of the Empire during this reign was shown also by the fact that the Britons (from whose country the Roman troops had been withdrawn forty years before), finding it vain to apply to Rome for aid against the incursions of the Picts, invited the Jutes under Hengest and Horsa to help them, in 449. The Goths likewise established themselves in Gaul; but Aetius finally made peace with them (439 A.D.), and with their assistance gained a great victory over Attila and the vast army of the Huns at Châlons in 451. (See Attila.) The power and influence of Aetius excited the jealousy and fears of Valentinian, who murdered his faithful general in 454. (See Aetius.) In the following year the emperor himself was slain by Petronius Maximus, whose wife he had violated.