Edward Gibbon refers to him as "the man universally celebrated as the terror of Barbarians and the support of the Republic" for his victory at the Catalaunian Plains.

[8] Aetius' mother, whose name is unknown, was a wealthy aristocratic woman of ancestry from Rome or some other city in the Italian peninsula.

[15] Some modern historians have suggested that Aetius's upbringing amongst militaristic peoples gave him a martial vigour not common in contemporary Roman generals.

[17] The Eastern Emperor Theodosius II organised a military expedition westward, led by Ardaburius and his son Aspar, to put his cousin, the young Valentinian III (who was a nephew of Honorius), on the western throne.

Shortly afterwards, Aetius returned to Italy with a large force of Huns to find that power in the west was now in the hands of Valentinian III and his mother Galla Placidia.

Once Felix was dead, Aetius was the highest ranking amongst the magistri militiae, even if he had not yet been granted the title of patricius or the senior command.

During 430 and 431 Aetius was in Raetia and Noricum, re-establishing Roman rule on the Danubian Limes, campaigning against the Juthungi[27] and defeating the Bagaudae in Augusta Vindelicorum.

Bonifacius was given the rank of patrician and made the senior comes et magister utriusque militiae, while Aetius was stripped of his military command.

[34] From 433 to 450, Aetius was the dominant figure in the Western Empire, obtaining the rank of magnificus vir parens patriusque noster (5 September 435) and playing the role of "protector" of Galla Placidia and Valentinian III while the Emperor was still young.

In 436, the Burgundians of King Gundacar were defeated and obliged to accept peace by Aetius and Avitus; however, the following year he sent Hun foederati to destroy them.

The year 437 saw his second consulship and the wedding of Valentinian and Licinia Eudoxia in Constantinople; it is probable that Aetius attended the ceremony that marked the restoration of the direct rule of the Emperor.

[39] On his return to Italy, he was honoured by a statue erected by the Senate and the People of Rome by order of the Emperor; this was probably the occasion for the panegyric written by Merobaudes.

[45] The foederati were stopped in an ambush near Vicus Helena, where Aetius directed the operations while his commander Majorian (later Emperor) fought with the cavalry.

Then the joint Roman and Visigothic army moved to relieve the besieged city of Aurelianum, forcing the Huns to abandon the siege and retreat to open country.

[55] Attila invaded and ravaged Italy, sacking numerous cities and razing Aquileia completely, allegedly leaving no trace of it behind.

[56] Edward Gibbon however says Aetius never showed his greatness more clearly in managing to harass and slow Attila's advance with only a shadow force.

Attila finally halted at the Po, where he met an embassy including the prefect Trygetius, the ex-consul Gennadius Avienus, and Pope Leo I.

Ancient and medieval historians tended to give Pope Leo and supernatural forces credit for halting Attila,[57][58] but a number of practical factors may have also induced Attila to retreat: his army was unable to obtain sufficient food and was suffering from disease, Aetius' army was busy harassing the Huns, and finally Marcian had sent forces north of the Danube to attack the homelands of the Huns and their vassals under a separate Aetius.

Seeking revenge, Maximus arranged with two Huns who were friends of Aetius, Optila and Thraustila, to assassinate both Valentinian III and Heraclius.

Traditionally, historians also consider the Battle of the Catalaunian Plains as decisively important, crippling Attila by destroying his aura of invincibility.

[64] Gibbon states this view: [Attila's] retreat across the Rhine confessed the last victory which was achieved in the name of the Western Roman Empire.

[65] Aetius effectively ruled the western empire from 433 to 454, and attempted to stabilize its European borders under a deluge of barbarians, foremost of which were Attila and the Huns.

Regarding this, historian Arther Ferrill states: After he secured the Rhine, Attila moved into central Gaul and put Orléans under siege.

Even though all parties to the protection of the Western Roman Empire had a common hatred of the Huns, it was still a remarkable achievement on Aetius' part to have drawn them into an effective military relationship.

For Bury, the result of the Battle of the Catalaunian Plains determined chiefly that Attila spent his last year looting Italy, rather than Gaul.

Modern authors typically overlook the battle and focus on the greater impact of Aetius' career, and he is generally seen as one of the greatest Roman military commanders of all time, as well as an excellent diplomat and administrator.

Meghan McEvoy states that the Battle of the Catalaunian Plains is more a testament to his political aptitude than his military skill due to his foresight in the ability to provision treaties and obligations.

[71] Heather states that the rise of Attila ultimately led to the loss of Africa as the Eastern Roman army and navy, which was bearing the brunt of the cost for the expedition, had to be recalled to the Balkans.

[72] Halsall argues that the black mark on Aetius' career was his mixed success in Spain, where the majority of the province was lost by 449, although he later rectified this.