When Valentinian (III), the nephew of the Eastern Roman emperor Honorius, became western emperor, he was still a child, and under the regency of his mother Galla Placidia. The general Boniface supported her, and she him, but Aetius wanted the power. Eventually, when Boniface died, Aetius succeeded him as master of soldiers and by 433 had become de facto ruler of the western Empire, from which position he waged campaigns against barbarian threats. He waged war against the Vandals and Alans, forcing Geiseric into negotiations in 435. He also sought the help of the Huns in Gaul. After the death of Attila, Aetius' importance waned, and Valentinian III, in his 30s, was able to take control. On September 21 or 22, 454, Valentinian and his eunuch Heraclius murdered Aetius.
Source: Peter Heather The Fall of the Roman Empire.
