The Battle of Abritus was a battle between Roman Empire with 15000 soldiers and a federation of 20000 Scythian tribesmen under the Goth king Cniva in the Roman province of Moesia Inferior in July, 251. It was a decisive Gothic victory, and in addition the Roman emperors Decius and his son Herennius Etruscus were both killed during battle. They became the first Roman emperors killed in a battle with a foreign enemy.

The Gothic invaders headed south to plunder Nicopolis ad Istrum where Decius defeated them but not decisively. After these initial setbacks, the barbarians moved southwards through Haemus mountain and Decius pursued them (likely through the Shipka Pass) to save Philippopolis. This time Decius' army was taken by surprise while resting at Beroe/Augusta Traiana. The Romans were heavily defeated in the ensuing battle. Decius was forced to withdraw his army to the north at Oescus, leaving Cniva ample time to ravage Moesia and finally capture Philippopolis in the summer of 251, in part with the help of its commander, a certain Titus Julius Priscus who had proclaimed himself Emperor. It seems that Priscus, after receiving the news of the defeat at Beroe, thought that the Goths would spare him and the city. He was wrong and was probably killed when the city fell.Then the Scythians began returning to their homeland, laden with booty and captives, among them many of senatorial rank.

The strengths of the bellingerent forces are unknown, but we know that Cniva divided his forces into three units, with one of these parts concealed behind a swamp. It seems that Cniva was a skilled tactician and that he was very familiar with the surrounding terrain

The manoeuvre of the Scythians was ultimately successful. Decius' forces defeated their opponents in the front line, but made the fatal mistake of pursuing their fleeing enemy into the swamp, where they were ambushed and routed. The immense slaughter marked one of the most catastrophic defeats in the history of the Roman Empire and resulted in the death of Decius himself.

Gallus, who became emperor upon Decius' death, negotiated a treaty with the Goths under duress, which allowed them to keep their booty and return to their homes on the other side of the Danube. It is also possible that he agreed to pay an annual tribute in return for the Goths' promise to respect Roman territory.