When the Goths, under Cniva, invaded the Danubian provinces, he was sent with a vanguard, followed by the main body of Roman troops, led by Decius.

Cniva was prevented from laying siege to Novae by Trebonianus Gallus, the governor of Moesia and future emperor, and thus moved south, on to Nicopolis.

Cniva then ambushed the forces of Decius and Herennius Etruscus at the Battle of Beroe, near the small town of Beroca at the base of the Haemus Mons.

The Roman forces were beaten decisively in this engagement and fled in disarray to Moesia where Decius and Herennius Etruscus worked to reorganize them.

Cniva then returned to Philippopolis, and with the help of Titus Julius Priscus, the Roman governor of Thrace, managed to capture the city.

After the news of his death reached Decius, he refused to be consoled, stating that the loss of one life was minor to a battle, and thus continued the combat, in which he was also slain.

[2][9] The reserve forces of Trebonianus Gallus failed to reinforce the main army in time to save Decius and Herennius Etruscus, although whether this was due to treachery or misfortune is unknown.

[10] After the death of both Decius and Herennius Etruscus, and much of the Roman army with them, the remaining forces immediately elected Trebonianus Gallus, the governor of Moesia, as emperor.