Trajan Decius was a Roman emperor who ruled from 249 to 251 AD. He was born in Illyricum, a province on the Danube river, and rose to prominence as a senator and a military commander under Philip the Arab. He became emperor after defeating Philip in a civil war and was recognized by the Senate with the name Traianus, in honor of the previous emperor Trajan.

Decius faced many challenges during his short reign, such as invasions by the Goths and other barbarian tribes, economic difficulties, and internal dissent. He tried to restore the glory and stability of the empire by promoting traditional Roman religion and culture, and by launching a campaign of persecution against the Christians, who he saw as a threat to the imperial unity. He ordered all citizens to perform a sacrifice to the pagan gods and obtain a certificate of compliance, or face imprisonment, torture, or death. Many Christians refused to comply and suffered martyrdom, while others apostatized or fled.

Decius also fought bravely against the Goths, who had crossed the Danube and raided the provinces of Moesia and Thrace. He won several battles, but was eventually killed along with his son and co-emperor Herennius Etruscus at the Battle of Abritus in 251 AD. His death marked the end of his persecution and the beginning of a period of crisis and chaos for the Roman Empire.