[7] His praenomen and nomen, reinforced by his cognomen, suggest a descent from a native African who obtained Roman citizenship during the Second Triumvirate, in which his land was ruled by Lepidus.

Gallus secured the throne after the death of Emperor Decius at the hands of Cniva in the Battle of Abrittus (251), and later had to manage an outbreak of plague that devastated Rome.

[8] Aemilian had command of the army assigned to defend the area, but the recent defeat at the Battle of Abrittus put his troops on edge.

[12] With his few men, Aemilian left his province unguarded and moved quickly towards Rome to meet the legitimate emperor, Gallus, before the latter could receive reinforcements.

[8] The two armies met at the Battle of Interamna Nahars near modern Terni, at the southern end of the eastern branch of the Flaminia, and Aemilian won the battle;[14] Gallus and Volusianus fled to the north with a few followers, probably as a delay tactic before the arrival of reinforcements, but, in late June or early August 253,[15] at Forum Flaminii (modern San Giovanni Profiamma), on the western branch of the Flaminia, they were killed by some of their own guards,[7] who thought that their betrayal could earn them a reward.

[19] His coinage shows that his propaganda focused on his capability as a military commander—he defeated the Goths when nobody thought this possible, and thus he was the right man for the job of restoring the power of the Roman Empire.

[20] But modern historians believe this army, possibly mobilized for an incumbent campaign in the East, moved only after Gallus' death to support Valerian's bid for power.

Aemilianus' sole reign was one of the shortest in Rome's history, as he only ruled about a month between Trebonianus Gallus' death and his own murder.