Flavius Placidius Valentinianus was born in 419 and was the only son of Constantius III.
Following the death of his father in 421, he and both his mother and sister, all moved to Constantinople which was currently under the rule of Honorius.
Two years later Honorius died and Theodosius had Valentinian elevated to the position of Caesar in order to control the west and would have him marry his daughter when he had gained a few years. At the age of 6, Valentinian became the emperor of the western empire.
During his reign much of the empire was lost, this included Africa being claimed by the Vandals, the abandonment of Britain, barbarians taking over great amounts of both Spain and Gaul, and Sicily being ravaged.
The reign however was also marked by His victory over Attila the Hun in 451 and multiple campaigns against the Visigoths which were all successful.
It was Valentinians’ murder of Aëtius in 454, the general who led the battle over Attila that was his down fall. A year later while the emperor was in Rome, two barbarian followers of Aëtius assassinated him and his position as emperor was quickly claimed by a wealthy senator named Petrinus Maximus.