Valentinian (Valentinianus), the name of three Roman emperors.

I. Flavins, Born At Oibalae, Pannonia

Pannonia Flavins Born At Oibalae, in A. D. 321, died at Bregetio, in the same proviace, Nov. 17, 375. He was the son of Count Gratian, and on the accession of Jovian in 363 he was made captain of the second company of the guards. On the death of Jovian at Dadastana in February, 364, the throne was offered by the army leaders to Valentinian, who was then at Ancyra. He assumed the purple on the plains of Nicaea, Feb. 26, and after reaching Constantinople made his brother Valens associate emperor with the control of the eastern provinces. Valentinian then went to Italy, and for some years was engaged in protecting the frontiers of the empire. He first fixed his headquarters at Lutetia (now Paris), and during 366 the Alemanni were defeated by his general Jovinus, the master of the horse. The following winter was spent at Durocortorum (Rheims), in building forts and taking other means of defence against the incursions of the Germans. In 367 the Alemanni surprised and plundered Moguntiacum (Mentz); but the emperor drove them back into their own country, defeating them at a place called Solicinum. In 370 the Saxons, who had made an incursion into Roman territory, were destroyed by an ambuscade.

In 374 Valentinian prepared for a campaign against the Quadi, but died at Bregentio, near the modern town of Comorn, as he was on the point of setting out. He was one of the ablest of the Roman emperors, but his character was disfigured by passion and cruelty. He was succeeded by his son Gratian.

II. Flavins

Flavins, son of the preceding, born about 371, strangled May 15, 392. Immediately on the death of his father, he was raised by the army to the imperial dignity, being but four or five years old; and although his brother Gratian consented to this arrangement, and made a partition of the western empire, assigning to Valentinian Italy, Illyricum, and Africa, Gratian really exercised the supreme authority over all the territory until his murder in 383. Then Theodosius took charge of Valentinian, and upheld his rights in 387 and 388 against the usurper Maximus. In 392 he endeavored to rid himself of his general and chief adviser Arbogast by dismissal, and a few days later was found strangled in his apartment at Vienna in Gaul.

III. Piacidins

Piacidins, emperor of the West, born about 419, assassinated in 455. He was the son of Constantius and Galla Placidia, daughter of Theodosius I. On Oct. 23, 425, he received from his cousin Theodosius II. the purple and the title of Augustus. The first years of his reign, while his mother Placidia ruled for him, were marked by the disastrous rivalry between the last two great Roman generals, Aetius and Boniface, and the consequent loss of Africa. In 437 Valentinian married at Constantinople Eudoxia, daughter of Theodosius. In the mean time the extreme provinces of the western empire were gradually attacked on all sides, and the Roman possessions were constantly diminishing. In 451 Aetius defeated Attila near Chalons-sur-Marne; but in 452 the latter ravaged the north of Italy. Aėtius was in 454 killed by Valentinian's own hand, whose feeble mind had long been jealous of the commanding intellect and haughty character of his greatest general. Valentinian himself, the following year, while viewing a spectacle in the Campus Martius, was slain at the instigation of the patrician Petronius Maximus, whose wife the emperor had a short time before violated, and who usurped the throne.

Valentinian was the last of the Theodosian line, and his vices were as conspicuous as his mental powers were contemptible.