Gaius Vibius Afininus Trebonianus Gallus was born around AD 206 into an old Etruscan family from Perusia.
Many blamed Gallus for the eventual defeat of Decius, claiming he had betrayed his emperor by secretly working with the Goths to see Decius killed. But there is little one can see today which would justify such allegations.
After the disastrous battle of Abrittus, Trebonianus Gallus was hailed was proclaimed emperor by his soldiers (AD 251).
Gallus then quickly marched back to Rome, hoping to secure his position by assuring good relations with the senate. He also took great care to show respect for Decius and his fallen son, ensuring their deification.
Decius' younger son Hostilianus, still too young to rule himself, was adopted and raised to the rank of Augustus to stand alongside Gallus as his imperial colleague.
Shortly after Hostilianus died and Volusianus was elevated to co-Augustus in his place.
Gallus' reign should suffer from a series of disasters, worst of which was a terrible plague which ravaged the empire for over a decade. One of the first victims of the disease had been the young emperor Hostilianus. The pestilence depleted the population and all but crippled the army, just when new, grave threats emerged on the frontiers. And so Gallus could do little as the Persians under Sapor I (Shapur I) overran Armenia, Mesopotamia and Syria (AD 252). Almost as powerless was he to prevent the Goths from terrifying the Danubian provinces and even raiding and devastating the northern shoreline of Asia Minor (Turkey).
Gallus, eager to find a means by which to distract attention from these grave dangers to the empire, revived the persecution of the Christians. Pope Cornelius was thrown into prison and died in captivity. But also other measures were taken in order to win favour. By creating a scheme by which even the very poor were entitled to a decent burial, he won much goodwill from ordinary people.
But in such troubled times it was only a matter of time before a challenger to the throne should emerge. In AD 253 Marcus Aemilius Aemilianus, governor of Lower Moesia, launched a successful attack on the Goths. His soldiers, seeing in him a man who at last could achieve victory over the barbarians, elected him emperor.
Though with no help possibly being able to arrive in time from Valerian, while faced with Aemilian's clearly superior Danubian troops, Gallus' soldiers did the only thing they could in order to avoid being slaughtered. They turned on their two emperors near Interamna and killed them both (August AD 253).