Gaius Messius Quintus Trajanus Decius ( 201 AD - June 251 AD), sometimes translated as Trajan Decius or Decius, was the emperor of the Roman Empire from 249 to 251.
A distinguished politician during the reign of Philip the Arab, Decius was proclaimed emperor by his troops after putting down a rebellion in Moesia. In 249, he defeated and killed Philip near Verona and was recognized as emperor by the Senate afterwards. During his reign, he attempted to strengthen the Roman state and its religion, leading to the Decian persecution, where a number of prominent Christians (including Pope Fabian) were put to death. In the last year of his reign, Decius co-ruled with his son Herennius Etruscus, until they were both killed by the Goths in the Battle of Abritus.
Traianus Decius was born Gaius Messius Quintus Decius Valerinus at Budalia, Illyricum, near Sirmium in Pannonia Inferior. Decius was one of the first among a long succession of Roman emperors (Illyrian emperors) to originate from the Danube provinces, often referred to as Illyricum. Unlike some of his immediate imperial predecessors such as Philip the Arab or Maximinus Thrax who did not have extensive administrative experience before assuming the throne, Decius was a distinguished senator who had served as suffect consul in 232, had been governor of Moesia and Germania Inferior soon afterwards, served as governor of Hispania Tarraconensis between 235 and 238, and was urban prefect of Rome during the early reign of Emperor Philip the Arab.
Around 245, Philip entrusted Decius with an important command on the Danube. By the end of 248 or 249, Decius was sent to quell the revolt of Pacatian and his troops in Moesia and Pannonia; some modern historians see this rebellion as a reflection of emerging Balkan separatism. After the collapse of the revolt, Decius let the troops proclaim him emperor. Philip advanced against him and was killed at Verona, Italy, in September 249. The Senate then recognized Decius as emperor, giving him the attribute Traianus in reference to Emperor Trajan.