Reign: September/October 249 – June 251 (c. 1 year and 8/9 months)
Crisis of the Third Century

Gaius Messius Quintus Trajanus Decius (c. 201 – June 251), sometimes translated as Trajan Decius, was Roman emperor from 249 to 251.

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. According to the Byzantine historian Zosimus, Decius was clothed in purple and forced to undertake the burdens of government, despite his reluctance and unwillingness.

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.

Decius' political program was focused on the restoration of the strength of the State, both militarily opposing the external threats, and restoring the public piety with a program of renovation of the state religion.

Either as a concession to the Senate, or perhaps with the idea of improving public morality, Decius endeavoured to revive the separate office and authority of the censor. The choice was left to the Senate, who unanimously selected Valerian (the future emperor). But Valerian, well aware of the dangers and difficulties attached to the office at such a time, declined the responsibility. The invasion of the Goths and Decius' death put an end to the abortive attempt.

During his reign, he proceeded with several building projects in Rome, including the Thermae Decianae (Baths of Decius in the Aventine), which were completed in 252 and survived through to the 16th century; Decius also repaired the Colosseum, which had been damaged by lightning strikes.

In late 249, Decius is said to have issued one of the most remarkable Roman imperial edicts. From the numerous surviving texts from Egypt, recording the act of sacrifice, it appears that the edict itself was fairly clear:

All the inhabitants of the empire were required to sacrifice before the magistrates of their community "for the safety of the empire" by a certain day (the date would vary from place to place and the order may have been that the sacrifice had to be completed within a specified period after a community received the edict). When they sacrificed they would obtain a certificate (libellus) recording the fact that they had complied with the order. That is, the certificate would testify the sacrificant's loyalty to the ancestral gods and to the consumption of sacrificial food and drink as well as the names of the officials who were overseeing the sacrifice.[10]
— D. S. Potter, The Roman Empire at Bay AD 180–395

According to D. S. Potter, Decius did not try to impose the superiority of the Roman pantheon over any other gods. It is very probable that the edict was an attempt to legitimize his position and to respond to a general unease provoked by the passing of the Roman millennium. While Decius himself may have intended the edict as a way to reaffirm his conservative vision of the Pax Romana and to reassure Rome's citizens that the empire was still secure, it nevertheless sparked a "terrible crisis of authority as various Christian bishops and their flocks reacted to it in different ways."Measures were first taken demanding that the bishops and officers of the church make a sacrifice for the emperor. The sacrifice was "on behalf of" (Latin pro) the emperor, not to the emperor, since a living emperor was not considered divine. Certificates were issued to those who satisfied the commissioners during the persecution of Christians under Decius. Forty-six such certificates have been published, all dating from 250, four of them from Oxyrhynchus. Anyone, including Christian followers, who refused to offer a sacrifice for the emperor and the Empire's well-being by a specified date risked torture and execution. A number of prominent Christians did, in fact, refuse to make a sacrifice and were killed in the process, including Pope Fabian himself in 250, and "anti-Christian feeling[s] led to killings at Carthage and Alexandria." However, towards the end of the second year of Decius' reign, "the ferocity of the [anti-Christian] persecution had eased off, and the earlier tradition of tolerance had begun to reassert itself." Despite no indication in the surviving texts that the edict targeted any particular group, Christians bore the brunt of the persecution and never forgot the reign of Decius, whom they remembered as "that fierce tyrant". In June 251 Decius died alongside his co-emperor Herennius Etruscus in the Battle Abrittus against the Goths; their successors Trebonianus Gallus and Hostilian rescinded Decius's decree, ending the persecution after approximately eighteen months.

At this time, there was a second outbreak of the Antonine Plague, which at its height from 251 to 266, took the lives of 5,000 daily[citation needed] in Rome. This outbreak is referred to as the "Plague of Cyprian" (Cyprian was the bishop of Carthage, where both the plague and the persecution of Christians were especially severe). Cyprian's biographer Pontius gave a vivid picture of the demoralizing effects of the plague[citation needed] and Cyprian moralized the event in his essay De mortalitate. In Carthage, the "Decian persecution", unleashed at the onset of the plague, sought out Christian scapegoats. Decius' edicts were renewed under Valerian in 253 and repealed under his son, Gallienus, in 260–261.
Fighting the Goths and death
The Gothic Invasions of 250–251 AD
See also: Gothic War (248-253)
The Goths enter the Balkans