During the years 425-429, the right-hand minister of Galla Placidia, the Master of Both Services, was Felix.
But Aetius by 429 had won such prestige by his successes in Gaul against the Goths and Franks (though Placidia had never forgiven him for his espousal of the cause of John) that he was able to impose his own terms, and extort from her the deposition of Felix and his own elevation to the post which Felix had occupied. He was appointed Master of Both Services in A.D. 429, and it is said that he at once caused Felix to be killed on suspicion of treachery. Then Boniface returned to Italy, where Placidia received him with favour, and soon afterwards she deposed the hated Aetius, who was consul of the year (A.D. 432), and gave his military command to the repentant rebel, on whom at the same time she conferred the dignity of patrician. Aetius refused to submit. There was civil war in Italy. The rivals fought a battle near Ariminum, in which Boniface was victorious, but he died shortly afterwards from a malady, perhaps caused by a wound. Aetius escaped to Dalmatia and journeyed to the court of his friend Rugila, the king of the Huns. By his help, we know not how, he was able to reappear in Italy, to dictate terms to the court of Ravenna, and obtain for himself reinstatement in his old office and elevation to the rank of patrician (A.D. 434).
In the meantime, during this obscure struggle for power, the Vandals were extending their conquests in Numidia. In spite of his wonderfully rapid career of success, Gaiseric was ready to come to terms with the Empire. Aetius, who was fully occupied in Gaul, where the Visigoths and Burgundians were actively aggressive, saw that the forces at his disposal were unequal to the expulsion of the Vandals, and thought that it was better to share Africa with the intruders than to lose it entirely. Gaiseric probably wished to consolidate his power in the provinces which he had occupied, and knew that any compact he might make would not be an obstacle to further conquests. Hippo, from which the inhabitants had fled, seems to have been reoccupied by the Romans, and here (February 11, A.D. 435) a treaty was concluded. The Vandals were to retain the provinces which they had occupied, viz. the two Mauretanias and a part of Numidia, but were to pay an annual tribute, thus acknowledging the overlordship of Rome.
Aetius had now firmly established his power, and Galla Placidia had to resign herself to his guidance. Valentinian was fifteen years of age, and the regency could not last much longer. The presence of the Master of Soldiers was soon demanded in Gaul, where the Visigoths were again bent on new conquests and where the Burgundians were invading the province of Upper Belgica (A.D. 435). Against the Burgundians he does not appear to have sent a Roman army; he asked his friends the Huns to chastise them. The Huns knew how to strike. It is said that 20,000 Burgundians were slain, and King Gundahar was one of those who fell (A.D. 436). Thus came to an end the first Burgundian kingdom in Gaul, with its royal residence at Worms. It was the background of the heroic legends which passed into the German epic—the Nibelungenlied. The Burgundians were not exterminated, and a few years later the Roman government assigned territory to the remnant of the nation in Sapaudia (Savoy) south of Lake Geneva (A.D. 443).
Narbonne was besieged by Theodoric, king of the Visigoths, in A.D. 436, but was relieved by Litorius, who was probably the Master of Soldiers in Gaul. Three years later the same commander drove the Goths back to the walls of their capital Toulouse, and it is interesting to find him gratifying his Hun soldiers by the performance of pagan rites and the consultation of the auspices. These ceremonies, however, did not help him. Fortune turned against him. He was defeated and taken prisoner in a battle outside the city. Avitus, the Praetorian Prefect of Gaul, who had great influence with Theodoric, then brought about the conclusion of peace. In these years there were also troubles in the provinces north of the Loire, where the Armoricans rebelled, and Aetius or his lieutenant Litorius was compelled to reimpose upon them the “liberty” of imperial rule.

In A.D. 437 Aetius was consul for the second time, and in that year Valentinian went to Constantinople to wed his affianced bride, Licinia Eudoxia the daughter of Theodosius. Now assuredly, if not before, the regency was at an end, and henceforward Aetius had to do in all high affairs not with Galla Placidia, who distrusted and disliked him, but with an inexperienced youth. Valentinian was weak and worthless. He had been spoiled by his mother, and had grown up to be a man of pleasure who took no serious interest in his imperial duties. He associated, we are told, with astrologers and sorcerers, and was constantly engaged in amours with other men’s wives, though his own wife was exceptionally beautiful. He had some skill in riding and in archery and was a good runner, if we may believe Flavius Vegetius Renatus, who dedicated to him a treatise on the art of war.
From the end of the regency to his own death, Aetius was master of the Empire in the west, and it must be imputed to his policy and arms that imperial rule did not break down in all the provinces by the middle of the fifth century. Of his work during these critical years we have no history. We know little more than what we can infer from some bald notices in chronicles written by men who selected their facts without much discrimination. If we possessed the works of the court poet of the time we might know more, for even from the few fragments which have survived we learn facts unrecorded elsewhere. The Spaniard, Flavius Merobaudes, did for Valentinian and Aetius what Claudian had done for Honorius and Stilicho, though with vastly inferior talent.
The position of Aetius in these years as the supreme minister was confirmed by the betrothal of his son to the Emperor’s daughter Placidia, an arrangement which can hardly have been welcome to Galla Placidia, the Augusta. With Valentinian himself he can hardly have been on intimate terms. The fact that he had supported the tyrant John was probably never forgiven. And it cannot have been agreeable to the young Emperor that it was found necessary to curtail his income and rob his privy purse in order to help the state in its financial straits. Little revenue could come from Africa, suffering from the ravages of the Vandals, and in A.D. 439, the richest provinces of that country passed into the hands of the barbarians. The income derived from Gaul, too, must have been very considerably reduced, and we are not surprised to find the government openly acknowledging in A.D. 444 that “the strength of our treasury is unable to meet the necessary expenses“.
Meanwhile the treaty of A.D. 435 was soon violated by Gaiseric. He did not intend to stop short of the complete conquest of Roman Africa. In less than five years Carthage was taken (October 19, A.D. 439). If there was any news that could shock or terrify men who remembered that twenty-nine years before Rome herself had been in the hands of the Goths, it was the news that an enemy was in possession of the city which in long past ages had been her most formidable rival. Italy trembled; for with a foe master of Carthage she felt that her own shores and cities were no longer safe. And, in fact, not many months passed before it was known that Gaiseric had a large fleet prepared to sail, although its destination was unknown. Rome and Naples were put into a state of defence; Sigisvult, Master of Soldiers, took steps to guard the coasts; Aetius and his army were summoned from Gaul; and the Emperor Theodosius prepared to send help. There was indeed some reason for alarm at Constantinople. The Vandal pirates could afflict the eastern as well as the western coasts of the Mediterranean; the security of commerce was threatened. It was even thought advisable to fortify the shores and harbours of the Bosphorus. The Mediterranean was no longer a Roman lake.
(Source: “The Invasion of Europe By the Barbarians”, by Bury, J.B.)
Research-Selection for NovoScriptorium: Anastasius Philoponus