After defeating Philip and consolidating his power in Rome, the emperor focused on a number of building projects including a repair of the aging Colosseum and the construction of the Baths of Decius.In 250 CE he returned to military service when he led forces to the Balkans to confront the resurging Goths who had crossed the Danube into the province of Thrace and attacked the city of Philippopolis.
During the reign of Philip, before he was sent to Moesia and Pannonia, he was the urban prefect of Rome.
In an odd turn of events, when Philip offered to step down as emperor, it was Decius who stopped his resignation, saying it was unnecessary.
His major concern was the leader of the Goths, Kniva.
Despite being repelled by Decius’ forces, the invading “barbarian” continued eastward where he was joined by the Carpi who had crossed into the Roman province of Dacia.
Unlike Priscus, he had some support in Rome both in the senate and withh the populace, but his rebellion and he would soon be put down by Publius Licinius Valerianus (a future emperor 253 - 260 CE) who had been appointed by Decius to attend to the administrative duties while he was gone.
Decius could not be bothered with these would-be emperors.
Although some historians believe Decius was reluctant to battle Philip, the armies of the two emperors met at Beroea in Macedonia where Decius defeated and killed Philip.
Shortly afterwards, Philip’s young son and heir was killed at the Praetorian camp in Rome. He would be the first in a long line of emperors from the Balkans.
With the hope of stopping Kniva, the emperor sent his oldest son Herennius to Moesia and Decius soon followed.
Unfortunately, both Decius and his son (who had been appointed co-emperor) were unable to repel Kniva and his combined forces.
Upon his return to Rome, he made Decius’ youngest son his co-emperor but the boy would die shortly afterwards.