Decius in the context of Antoninianus

Philip I (Latin: Marcus Julius Philippus; c. 204 – September 249), commonly known as Philip the Arab, was Roman emperor from 244 to 249. After the death of Gordian III in February 244, Philip, who had been Praetorian prefect, rose to power. He quickly negotiated peace with the Sasanian Empire and returned to Rome to be confirmed by the Senate. According to many historians, he was possibly the first Christian Roman Emperor.

Although his reign lasted only five years, it marked an unusually stable period in a century that is otherwise known for having been turbulent. Near the end of his rule, Philip commemorated Rome's first millennium. In September 249 he was killed during or shortly after the Battle of Verona against the usurper Trajan Decius, who was subsequently recognized by the Senate as his successor.

Early Christians were heavily persecuted throughout the Roman Empire until the 3rd century. Although Christianity initially emerged as a small Jewish movement in 1st-century Judaea, it quickly branched off as a separate religion and began spreading across the various Roman territories at a pace that put it at odds with the well-established Roman imperial cult, to which it stood in opposition; Christians were vocal in their expressions of abhorrence towards the beliefs and practices of Roman paganism, such as deifying and making ritual sacrifices to the Roman emperor or partaking in other methods of idolatry. Consequently, the Roman state and other members of civic society routinely punished Christians for treason, various rumoured crimes, illegal assembly, and for introducing an alien cult that drove many Roman people to apostasy in favour of Jesus Christ. According to Tacitus, the first wave of organized persecution occurred under Nero (r. 54–68), who blamed Christians for the Great Fire of Rome in 64. A number of mostly localized persecutions occurred during the reign of Marcus Aurelius (r. 161–180). After a lull, persecution resumed under Decius (r. 249–251) and Trebonianus Gallus (r. 251–253). The Decian persecution was particularly extensive, as Decius strived to restore the Roman golden age in part by forcing pagan practices upon the Christian community. Another wave of persecution began under Valerian (r. 253–260), but ceased abruptly after he was captured and taken prisoner by the Sasanian Empire during the Battle of Edessa of the Roman–Persian Wars. Under his successor Gallienus (r. 253–268), whose reign was marred by rapidly escalating military conflicts of the Crisis of the Third Century, the first ever decree of tolerance was issued for Christian practices and places of worship, although it stopped short of recognizing Christianity as a religion with legal status.

Emperor Diocletian (r. 283–305) began the Diocletianic persecution, which was the final and the most severe wave of persecution of Christians by the Roman state. It was enforced until the accession of Galerius (r. 305–311), who issued the Edict of Serdica, and the death of Maximinus Daza (r. 310–313). After Constantine the Great (r. 306–337) defeated his rival Maxentius (r. 306–312) at the Battle of the Milvian Bridge in October 312, he and his co-emperor Licinius issued the Edict of Milan, which decriminalized Christianity and suppressed pagan populations throughout the Roman Empire. In 380, Theodosius I (r. 379–395) issued the Edict of Thessalonica, officially establishing Christianity as the Roman state religion. It was also during the reign of Theodosius I that pagan practices were overtly deemed punishable offenses, which laid the framework for early Byzantine anti-pagan policies.

The Battle of Verona was fought between the Roman general and usurper Decius, and emperor Philip the Arab in 249. Decius was victorious and Philip and his son Philip II were both killed. Decius was subsequently declared Roman emperor.

Pacatianus, known in English as Pacatian (/ˈpəkeɪʃ(i)ən/; Latin: Tiberius Claudius Mar[...] Pacatianus; died c. 248) was a usurper in the Danube area of the Roman Empire during the time of Philip the Arab. His praenomen and nomen suggest his ancestors obtained Roman citizenship either during the time of Tiberius or of Claudius.

His life is known from mentions in the histories of Zosimus and Zonaras. However, the chronology of these accounts is obscure, and modern scholars use coinage to establish the timeline of his life and revolt. Zonaras names him as a 'unit commander' of one of the Danube legions, possibly Legio VII Claudia. He was likely a leader in the effort to drive Gothic invaders out of Roman territory in 248, one of the first actions of the Gothic War. Either during this action or soon after he was acclaimed emperor by the Danube legions. Eventually his control extended to the city of Viminacium. According to Zosimus, the news of Pacatian's revolt in Moesia and of Jotapian's near-simultaneous revolt in Syria prompted Philip to make an offer to the Roman Senate to step down. Both Zosimus and Zonoras relate that Philip was advised by the senator Decius, who predicted that Pacatian would soon be killed by his troops. This soon came to pass, and Philip (over Decius' objections) sent Decius to the Danube to find out the causes of the revolt. Decius was promptly acclaimed as emperor by the legions on the Danube, and (though Zonaras records that Decius offered to resign) eventually overcame Philip by the end of 249.

Christians were persecuted in 250 AD under the Roman emperor Decius. He had issued an edict ordering everyone in the empire to perform a sacrifice to the Roman gods and the well-being of the emperor. The sacrifices had to be performed in the presence of a Roman magistrate, and be confirmed by a signed and witnessed certificate from the magistrate. Although the text of the edict has been lost, many examples of the certificates have survived.

Decius' edict was intended to act as an empire-wide loyalty oath to the new emperor (who had come to power in 249 AD), sanctified through the Roman religion. Christian monotheistic beliefs did not allow them to worship any other gods, so they were forced to choose between their religious beliefs and following the decree.

The Diocletianic or Great Persecution was the last and most severe persecution of Christians in the Roman Empire. In 303, the emperors Diocletian, Maximian, Galerius, and Constantius issued a series of edicts rescinding Christians' legal rights and demanding that they comply with traditional religious practices. Later edicts targeted the clergy and demanded universal sacrifice, ordering all inhabitants to sacrifice to the Roman gods (Jews were exempt). The persecution varied in intensity across the empire—weakest in Gaul and Britain, where only the first edict was applied, and strongest in the Eastern provinces. Persecutory laws were nullified by different emperors (Galerius with the Edict of Serdica in 311) at different times, but Constantine and Licinius' Edict of Milan in 313 has traditionally marked the end of the persecution.

Christians had been subject to intermittent local discrimination in the empire, but emperors prior to Diocletian were reluctant to issue general laws against the religious group. In the 250s, under the reigns of Decius and Valerian, Roman subjects including Christians were compelled to sacrifice to Roman gods or face imprisonment and execution, but there is no evidence that these edicts were specifically intended to attack Christianity. After Gallienus's accession in 260, these laws went into abeyance. Diocletian's assumption of power in 284 did not mark an immediate reversal of imperial inattention to Christianity, but it did herald a gradual shift in official attitudes toward religious minorities. In the first fifteen years of his rule, Diocletian purged the army of Christians, condemned Manicheans to death, and surrounded himself with public opponents of Christianity. Diocletian's preference for activist government, combined with his self-image as a restorer of past Roman glory, foreboded the most pervasive persecution in Roman history. In the winter of 302, Galerius urged Diocletian to begin a general persecution of the Christians. Diocletian was wary and asked the oracle at Didyma for guidance. The oracle's reply was read as an endorsement of Galerius's position, and a general persecution was called on 23 February 303.

Quintus Herennius Etruscus Messius Decius (died c. June 251), known simply as Herennius Etruscus, was briefly Roman emperor in 251, ruling jointly under his father Decius. His father was proclaimed emperor by his troops in September 249 while in Pannonia and Moesia, in opposition to Philip. Decius defeated Philip in battle, and was then proclaimed emperor by the Senate. Etruscus, still a child, was elevated to Caesar (heir) in 250, then further raised to Augustus (emperor) in May 251. When the Goths, under Cniva, invaded the Danubian provinces, he was sent with a vanguard, followed by the main body of Roman troops, led by Decius. They ambushed Cniva at the Battle of Nicopolis ad Istrum in 250, routing him, before being ambushed and routed themselves at the Battle of Beroe. Etruscus was killed in the Battle of Abritus the following year, alongside his father. After the deaths of both emperors, Trebonianus Gallus, who had been governor of Moesia, was elected emperor by the remaining Roman forces.

Alexander of Jerusalem (Greek: Αλέξανδρος Ιεροσολύμων; died 251 AD) was a third century bishop who is venerated as a martyr and saint by the Eastern Orthodox Church, Oriental Orthodox churches, and the Roman Catholic Church. He died during the persecution of Emperor Decius.

The Battle of Abritus also known as the Battle of Forum Terebronii occurred near Abritus (modern Razgrad) in the Roman province of Moesia Inferior in the summer of 251. It was fought between the Romans and a federation of Gothic and Scythian tribesmen under the Gothic king Cniva. The Roman army was soundly defeated, and Roman emperors Decius and Herennius Etruscus, his son, were both killed in battle. It was one of the worst defeats suffered by the Roman Empire against the Germanic tribes, rated by the Roman historian Ammianus Marcellinus as on par with the Battle of the Teutoburg Forest in 9, the Marcomannic invasion of Roman Italy in 170, and the Battle of Adrianople in 378.

The emperors' deaths led to more political instability at Rome; and the loss of the army allowed repeated barbarian incursions in the region for the next two decades.

The Gothic War of 248–253 took place between the years 248 and 249, as well as in the year 253. Within this war, a series of battles occurred and plundering was carried out by the Goths and their allies in the eastern territory of the Roman Empire, specifically in the Balkans. With the cessation of the payment of tribute previously made by the Roman emperor Philip the Arab (r.  244–249) to the tribes beyond the Danube, the Goths and their allies, led by King Ostrogotha and his subcommanders Argedo and Gundericus, moved towards the Roman border and began a series of attacks, including against the fortified city of Marcianopolis (today Devnya) in Thracia. After these actions, the Goths withdrew with their spoils of war.

In 250, the invasions continued, the Carpiani attacked Dacia, while the Gothic King Cniva commanding various groups of Goths and other allied peoples, defeated the Romans in two major battles, in one of these he killed the Roman emperor Decius (r.  249–251) and his co-emperor Herennius Etruscus (r.  251). The imperial successor Trebonianus Gallus (r.  251–253) pledged to pay an annual tribute if the invaders left, however, he did not keep his promise, which provoked new attacks in 253, although the governor and future emperor Aemilianus (r.  253) managed to stop these raids.

Osroene (Ancient Greek: Ὀσροηνή), also spelled Osrohene and Osrhoene, was a Roman province which existed for nearly 400 years. It was formed after the absorption of the Kingdom of Osroene in 214 CE and served as a frontier province against the Sassanid Empire until the Muslim conquests of the 7th century.

For the whole of its existence, the province would remain a bone of contention between the Romans and their eastern neighbors, the Sassanid Persians, suffering heavily in the recurrent Roman–Persian Wars. War broke out after the death of the Roman emperor Decius in 251 and the province was invaded by the Persians. In the second half of the 250s, the Persian shah Shapur I (r. ca. 240–270) attacked the Roman east, which was defended by the Roman emperor Valerianus (r. 253–260), whom he captured at Edessa in 260. In the next year however, Shapur was heavily defeated by Odaenathus of Palmyra and driven out of Osroene and Mesopotamia.

Sremska Mitrovica (Serbian pronunciation: [srêːmskaː mîtroʋitsa]; Serbian Cyrillic: Сремска Митровица, Latin: Sirmium) is a city in Serbia. It is situated on the left bank of the Sava river. As of 2022, the city has a total population of 36,764 inhabitants, while its administrative area has a population of 72,580 inhabitants.

As Sirmium, it was a capital of the Roman Empire during the Tetrarchy of 4th century CE. Ten Roman emperors were born in or near this city, Emperors Herennius Etruscus (251), Hostilian (251), Decius Traian (249–251), Claudius Gothicus (268–270), Quintillus (270), Aurelian (270–275), Probus (276–282), Maximian (285–310), Constantius II (337–361) and Gratian (367–383).

Gaius Vibius Volusianus (Latin: Gaius Vibius Afinius Gallus Veldumnianus Volusianus; died August 253), commonly called Volusian, was a Roman emperor from 251 to 253, ruling with his father Trebonianus Gallus.

After Emperor Decius and his son and co-ruler Herennius Etruscus died in battle in June 251, Trebonianus Gallus was elected emperor in the field by the legion. Gallus raised Hostilian, the younger son of Decius, to augustus (co-emperor) and elevated Volusianus to caesar. After the death of Hostilian in July or August 251, Volusianus was raised to augustus. The short reign of Gallus and Volusianus was notable for the outbreak of a plague, which is said by some to be the reason for Hostilian's death, and for hostilities with the Sasanian Empire and the Goths. Volusianus and his father were killed in August 253 by their own soldiers, who were terrified of the forces of the usurper Aemilian which were marching towards Rome.

Mercurius (Greek: Ἅγιος Μερκούριος, Coptic: Ⲫⲓⲗⲟⲡⲁⲧⲏⲣ Ⲙⲉⲣⲕⲟⲩⲣⲓⲟⲥ; {Ge'ez መርቆሬዎስ}Syriac: ܡܳܪܩܘ̇ܪܝܘ̇ܣ; 224/225 – 250 AD) was a Roman soldier of Scythian descent who became a Christian saint and martyr. He was born in the city of Eskentos in Cappadocia, in Eastern Asia Minor (modern-day Turkey). According to Christian tradition, he was the soldier who killed Julian the Apostate during his campaign in Persia. Saint Mercurius was also widely known by his Arabic-language name Abu-Sayfain, Abu-Sifin or Abu-Sefein in Egyptian Arabic (Arabic: أبو سيفين, romanized: Abū Seyfaīn; Coptic: ⲁⲃⲩⲥⲉⲫⲁⲓⲛ, romanized: Abû-Sefaīn) which means "wielder of two swords", referring to the second sword given to him by the Archangel Michael.

St. Mercurius was born around 225 A.D. in Cappadocia (Eastern Asia Minor) into a family of Scythian descent. His parents were converts to Christianity and they called him "Philopateer" or "Philopatyr" (a Greek name which means 'Lover of the Father'). They raised him in a Christian manner. When he grew to adulthood (at the age of 17), he enlisted in the Roman army in the reign of Emperor Decius. He gained a great reputation among his superiors as a swordsman and a tactician in many battles.

Denis of Paris (Latin: Dionysius) was a 3rd-century Christian martyr and saint. According to his hagiographies, he was bishop of Paris (then Lutetia) in the third century and, together with his companions Rusticus and Eleutherius, was martyred for his faith by decapitation. Some accounts placed this during Domitian's persecution and incorrectly identified St Denis of Paris with the Areopagite who was converted by Paul the Apostle and who served as the first bishop of Athens. Assuming Denis's historicity, it is now considered more likely that he suffered under the persecution of the emperor Decius shortly after AD 250.

Denis is the most famous cephalophore in Christian history, with a popular story claiming that the decapitated bishop picked up his head and walked several miles while preaching a sermon on repentance. He is venerated in the Catholic Church as a patron saint of both France and Paris and is one of the Fourteen Holy Helpers. A chapel was raised at the site of his burial by a local Christian woman; it was later expanded into an abbey and basilica, around which grew up the French city of Saint-Denis, now a suburb of Paris.

Cniva (fl. mid-3rd century AD) was a Gothic king who invaded the Roman Empire in the middle of the 3rd century AD. His regnal years are uncertain. He successfully captured the city of Philippopolis (Plovdiv in Bulgaria) in 250 and killed Emperor Decius and his son Herennius Etruscus at the Battle of Abritus as he was attempting to leave the Empire in 251. This was the first time a Roman Emperor had been killed in combat against foreigners. He was allowed by the new Emperor Trebonianus Gallus to leave with his spoils and was paid tribute to stay out of the empire.