Aetius, a general of the western empire, born in Mœsia about A. D. 896, murdered in 454. He was brought up, owing to the influence of his high-bred Italian mother, in the imperial body guard of Honorius, and after the death of his father Gaudentius, an illustrious Scythian and master general of cavalry, who lost his life in a mutiny, he was given as a hostage to the king of the Huns. On his return to Rome he was made count on occasion of his marriage with the daughter of Carpileo, and became attached to the household of Joannes. After an ineffectual support of this usurper in 425 with an army of 60,000 Huns, whom Aetius conducted into Italy under the guidance, it is said, of the then youthful Attila, he turned traitor against the treacherous cause he had espoused, and after the death of Joannes he succeeded in obtaining from Placidia, mother of Valentinian III., the chief command over the army of Gaul, as the condition of his procuring the peaceful retreat of the Huns. In this post he displayed great military skill, delivering Aries from the Visigoths, recovering from Chlodio, king of the Franks, the parts of Gaul bordering on the Rhine, overpowering the Juthungi in Bavaria, bringing to an end the Vindelician war, and in the following spring crushing the confederated forces of the Burgundians, Huns, Heruli, Franks, Sarmatians, Salians, and Ge-loni, in one terrible encounter.

In 432 his rival Boniface, who had been urged to treason and then betrayed by himself, returning from the province of Africa, which his treason had thrown into the hands of the Vandals, and obtaining the dignity of master of the horse, they fought a duel at Ravenna on the challenge of Aetius, of the wounds received in which Boniface soon afterward died. But Aetius, fearing for his life, which was threatened by his late rival's adherents, fled into Pannonia, and led a second army of nuns into Italy, threatened the throne of Valentinian, and, although the feeble emperor called in the aid of the Visigoths, forced the empress and her son, without an engagement, to submit to his terms, and returned as before with accumulated honors, to resume command of the army of Gaul. Here he once more displayed genius as a general, routing the Burgundians with exceeding slaughter, and forcing their king to throw himself on his mercy. In the mean time, Roas, king of the Huns, died, and was succeeded by Attila and his brother Bleda, the latter of whom being soon murdered, Attila assumed the sole dominion, and was speedily involved in hostilities with both the Roman empires.

For several years his arms were directed chiefly against the eastern empire, but in 451 he set in motion his vast army of a thousand nations, debouched from the defiles of the Hercvnian forest, crossed the Rhine on rafts, and fell like a torrent on the rich plains of Gaul. Here for a time all fell before him, till, when he was in the very act of storming the walls of Orleans, while his Huns were mounting the breaches, the spears of Aetius and Theodoric the Visigoth appeared on the horizon, and, amid cries of "The aid of God " from the beleaguered citizens, the siege was raised, and the Hunnish hordes were forced to retreat. Some days later a tre-mendous pitched battle was fought on the field of Chalons, in Champagne, in which 162,000, or, according to other accounts, 300,000 men fell on both sides. The Huns were so completely defeated, that Attila prepared a funeral pile and contemplated burning himself alive, with his treasures, his women, and his baggage wagons, had the Romans renewed the battle on the following day. But Theodoric lay dead, and Aetius suffered the Huns to escape.

After this he purposely remained inactive during the remainder of the war, took no measures to oppose the invasion of Italy, and even advised Valentinian to evacuate that country and take refuge in Gaul, which would have left himself master of Rome, where by his great abilities he would speedily have rid himself of the Huns and assumed the imperial purple. Aetius is believed, according to Marcellinus, to have been implicated m the sudden death of Attila (453); but there is no evidence to support this, excepting that Aetius always had his emissaries, in the shape of confidential Greek secretaries, about the person of Attila, who had never ceased to intrigue with him. In the end he fell by a crime and a treason as base as his own, stabbed by Valentinian with his own hand, during a friendly interview. The circumstances of this murder are not clearly known, although a coin which has been preserved, bearing the inscription Aetius Impera-tor CAesar, proves that he had assumed the imperial purple, and actually declared himself emperor, before he was killed. Nominally a Roman, he invariably betrayed Rome to the barbarians except when it was for his own interest to defend her, and then the ease with which he conquered them showed what he might have done had he been honest.

Nominally a Christian, he brought up one of his sons, Carpileo, in a heathen court, as a heathen, and destined him to wear the crown of a heathen nation; while the other, Gaudentius, he proposed to invest, after himself, with the purple of the western empire. Gibbon says that during the decay of the military spirit, the Roman armies were commanded by two generals, Aetius and Boniface, who may be deservedly called the last of the Romans.