Constantine the Great was a Roman Emperor from 306-337 CE. Constantine was the son of Flavius Valerius Constantius, a Roman army officer, and his consort, Helena. His father became Caesar, the deputy emperor in the west, in 293 CE. Constantine was sent east, where he rose through the ranks to become a military tribune under the emperors Diocletian and Galerius. In 305, Constantius was raised to the rank of Augustus, senior western emperor, and Constantine was recalled west to campaign under his father in Britannia (modern Great Britain). Acclaimed as emperor by the army at Eboracum (modern-day York) after his father’s death in 306 CE, Constantine emerged victorious in a series of civil wars against the emperors Maxentius and Licinius, to become sole ruler of both west and east by 324 CE.

As emperor, Constantine enacted many administrative, financial, social, and military reforms to strengthen the empire. The government was restructured and civil and military authority separated. A new gold coin, the solidus, was introduced to combat inflation. It would become the standard for Byzantine and European currencies for more than a thousand years. As the first Roman emperor to claim conversion to Christianity, Constantine played an influential role in the proclamation of the Edict of Milan in 313, which decreed tolerance for Christianity in the empire. He called the First Council of Nicaea in 325, at which the Nicene Creed was professed by Christians. In military matters, the Roman army was reorganized to consist of mobile field units and garrison soldiers capable of countering internal threats and barbarian invasions. Constantine pursued successful campaigns against the tribes on the Roman frontiers—the Franks, the Alamanni, the Goths, and the Sarmatians—even resettling territories abandoned by his predecessors during the Crisis of the Third Century.

Constantine’s reputation flourished during the lifetime of his children and for centuries after his reign. The medieval church upheld him as a paragon of virtue, while secular rulers invoked him as a prototype, a point of reference, and the symbol of imperial legitimacy and identity. One of his major political legacies, aside from moving the capital of the empire to Constantinople, was that, in leaving the empire to his sons, he replaced Diocletian’s tetrarchy with the principle of dynastic succession.

The Battle of the Milvian Bridge

Eusebius of Caesarea, and other Christian sources, record that Constantine experienced a dramatic event in 312 at the Battle of the Milvian Bridge, after which Constantine claimed the emperorship in the west, and converted to Christianity. The Battle of the Milvian Bridge took place between the Roman Emperors, Constantine I and Maxentius, on October 28, 312. It takes its name from the Milvian Bridge, an important route over the Tiber. Constantine won the battle and started on the path that led him to end the tetrarchy and become the sole ruler of the Roman Empire. Maxentius drowned in the Tiber during the battle, and his body was later taken from the river and decapitated.

According to chroniclers, such as Eusebius of Caesarea and Lactantius, the battle marked the beginning of Constantine’s conversion to Christianity. Eusebius of Caesarea recounts that Constantine looked up to the sun before the battle and saw a cross of light above it, and with it the Greek words Ἐν Τούτῳ Νίκα (“in this sign, conquer!”), often rendered in a Latin version, “in hoc signo vinces.” Constantine commanded his troops to adorn their shields with a Christian symbol (the Chi-Rho), and thereafter they were victorious. The Arch of Constantine, erected in celebration of the victory, certainly attributes Constantine’s success to divine intervention; however, the monument does not display any overtly Christian symbolism, so there is no scholarly consensus on the events’ relation to Constantine’s conversion to Christianity.

Missorium depicting Constantine’s son Constantius II, accompanied by a guardsman with the Chi Rho monogram depicted on his shield.

Following the battle, Constantine ignored the altars to the gods prepared on the Capitoline, and did not carry out the customary sacrifices to celebrate a general’s victorious entry into Rome, instead heading directly to the imperial palace. Most influential people in the empire, however, especially high military officials, had not been converted to Christianity, and still participated in the traditional religions of Rome; Constantine’s rule exhibited at least a willingness to appease these factions. The Roman coins minted up to eight years after the battle still bore the images of Roman gods. The monuments he first commissioned, such as the Arch of Constantine, contained no reference to Christianity.

Constantine and Christianity

While the Roman Emperor Constantine the Great reigned (306-337 CE), Christianity began to transition to the dominant religion of the Roman Empire. Historians remain uncertain about Constantine’s reasons for favoring Christianity, and theologians and historians have argued about which form of Early Christianity he subscribed to. There is no consensus among scholars as to whether he adopted his mother Helena’s Christianity in his youth, or (as claimed by Eusebius of Caesarea) encouraged her to convert to the faith himself. Some scholars question the extent to which he should be considered a Christian emperor: “Constantine saw himself as an ’emperor of the Christian people.’ If this made him a Christian is the subject of debate,” although he allegedly received a baptism shortly before his death.

Constantine’s decision to cease the persecution of Christians in the Roman Empire was a turning point for early Christianity, sometimes referred to as the Triumph of the Church, the Peace of the Church, or the Constantinian Shift. In 313, Constantine and Licinius issued the Edict of Milan, decriminalizing Christian worship. The emperor became a great patron of the Church and set a precedent for the position of the Christian emperor within the Church, and the notion of orthodoxy, Christendom, ecumenical councils, and the state church of the Roman Empire, declared by edict in 380. He is revered as a saint and isapostolos in the Eastern Orthodox Church and Oriental Orthodox Church for his example as a “Christian monarch.”

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