The short reign of Gallus and Volusianus was notable for the outbreak of a plague, which is said by some to be the reason for Hostilian's death, and for hostilities with the Sasanian Empire and the Goths.

Volusianus was the son of Trebonianus Gallus,[3] who was named emperor in July 251 after his predecessors, Decius and Herennius Etruscus, died fighting the Goths at the Battle of Abritus.

[3][4][5] Elected by the troops in the field, Gallus signed a treaty, decried by contemporary historians as "shameful", which promised tribute to the Goths if they abstained from raiding.

[6] He subsequently made a bid for popularity by declaring Hostilian, the surviving son of Decius, augustus (emperor) with him, voluntarily sharing his power with the prior imperial family.

[8] The reason for his death is disputed:[5] Aurelius Victor and the author of the Epitome de Caesaribus both say that Hostilian died of a plague, but Zosimus claims that Trebonianus Gallus murdered the young augustus so that Volusianus could take his place.

[6] During the reign of Trebonianus Gallus and Volusianus, the persecution of Christians was not as extreme as it was under Decius, although Pope Cornelius was exiled in 252 AD.

[6] When the news reached Rome, Gallus and Volusianus called for reinforcements from Valerian, the future emperor, who had been strengthening the empire's defences on the Rhine.