Constantine the Great

Constantine was born on February 27, 272 CE, in Naissus, a garrison town in the Roman province of Moesia, on the site of the modern Serbian city of Nis ^[1]. His father, Flavius Constantius, was a career officer from the Danubian provinces who rose steadily through the military hierarchy. His mother, Helena, came from humble origins; later tradition described her as an innkeeper's daughter from Bithynia, and her low status meant the union may never have been a formal marriage ^[2].

The empire of Constantine's childhood was recovering from decades of civil war, plague, and invasion. In 293 the emperor Diocletian reorganized imperial rule into a college of four rulers, the Tetrarchy, with two senior emperors (Augusti) and two junior colleagues (Caesars). Constantius was appointed Caesar in the West, and as part of the political arrangement he set Helena aside to marry Theodora, the stepdaughter of the Augustus Maximian ^[1].

The young Constantine was sent east to the court of Diocletian at Nicomedia. Officially he received an education there; in practice he also served as a guarantee of his father's loyalty. He campaigned under Diocletian and later under Galerius, gaining experience on the Danube frontier and in Persia, and he was present at Nicomedia in 303 when Diocletian launched the Great Persecution, the harshest official assault on Christians in Roman history ^[3].

In 305 Diocletian and Maximian abdicated, and Constantius became senior Augustus in the West. Constantine, still effectively a hostage at the eastern court, obtained permission from Galerius to join his father and rode across Europe to reach him. He arrived in time to campaign with Constantius in northern Britain against the Picts ^[1].

Constantius died at Eboracum, modern York, on July 25, 306. His troops immediately acclaimed Constantine as Augustus, an act that ignored the rules of the Tetrarchy, which did not recognize hereditary succession ^[2]. Galerius grudgingly recognized him with the lesser rank of Caesar, and Constantine accepted the compromise while consolidating his hold on Britain, Gaul, and Spain. He proved an effective frontier commander, defeating Frankish and Alamannic incursions along the Rhine and strengthening the fortifications of his capital at Trier.

The tetrarchic system soon collapsed into open competition among six claimants. Constantine's decisive move came in 312, when he invaded Italy against Maxentius, who held Rome. According to accounts written by Lactantius and Eusebius, Constantine experienced a vision or dream before the campaign's climactic battle and ordered his soldiers to mark their shields with a Christian sign ^[3]. On October 28, 312, he defeated Maxentius at the Battle of the Milvian Bridge just north of Rome. Maxentius drowned in the Tiber, and Constantine entered the city as master of the western empire ^[1]. He attributed the victory to the God of the Christians, a claim he repeated for the rest of his life.

Any account of Constantine the Great achievements begins with religious policy. In 313 Constantine met his eastern colleague Licinius at Milan, and the two agreed on a policy of full religious toleration, restoring confiscated property to Christian communities. The agreement, conventionally called the Edict of Milan, ended the era of persecution and gave Christianity legal standing throughout the empire ^[4]. Constantine went further in his own territories: he exempted clergy from civic burdens, gave bishops judicial authority in certain disputes, and financed major churches, including the original basilica of St. Peter in Rome and the Church of the Holy Sepulchre in Jerusalem ^[3].

When a dispute over the teachings of the Alexandrian priest Arius threatened to split the eastern church, Constantine summoned bishops from across the Roman world to Nicaea in 325. The Council of Nicaea, the first ecumenical council in Christian history, condemned Arius and produced a creed affirming that the Son was of the same substance as the Father ^[4]. The emperor presided over parts of the proceedings himself, setting a precedent for imperial involvement in church affairs that shaped Byzantine and medieval politics for centuries.

His secular reforms were nearly as consequential. Constantine completed the separation of civil and military commands begun under Diocletian, expanded the mobile field army, and reorganized the imperial court. In 324 he introduced the gold solidus, a coin struck at 72 to the Roman pound; it remained the standard of Mediterranean commerce for roughly seven centuries ^[1]. And after defeating Licinius in 324 to become sole ruler of the whole empire, he refounded the old Greek city of Byzantium as Constantinople, dedicating it on May 11, 330. Positioned on the Bosporus between Europe and Asia, the new capital gave the empire a defensible administrative center in the wealthy East and endured as the seat of Roman government until 1453 ^[5].

Constantine's domestic life mixed political calculation with episodes of real darkness. His first partner, Minervina, bore him a son, Crispus, around 300. In 307 he married Fausta, daughter of the former emperor Maximian, sealing an alliance with her family; she bore him three sons, Constantine II, Constantius II, and Constans, along with two daughters ^[2].

The alliance with Maximian's house ended violently. Maximian attempted a coup against Constantine in 310 and died shortly afterward, either by execution or forced suicide. Far worse came in 326, when Constantine ordered the execution of his eldest son Crispus, by then a successful commander and Caesar, and soon afterward had Fausta killed as well ^[1]. The sources closest to the events are silent or contradictory about the reasons, and later writers filled the gap with rumors of adultery or false accusation. Modern historians treat every explanation as conjecture; the facts of the deaths are secure, the motive is not ^[3].

His mother Helena remained a constant presence. Constantine granted her the title Augusta, and around 326 she traveled through Palestine, sponsoring churches at Bethlehem and on the Mount of Olives. Later Christian tradition credited her with discovering the True Cross in Jerusalem, and she was venerated as a saint in both eastern and western churches ^[4].

After 330 Constantine governed from Constantinople, devoting attention to the Danube frontier, where he won victories over the Goths in 332 and the Sarmatians in 334, and briefly restored a bridge across the river into former Roman Dacia ^[1]. He continued to legislate on matters ranging from the treatment of slaves to Sunday rest, and he kept up a heavy correspondence with bishops as fresh theological quarrels, including the continuing Arian controversy, refused to die.

Planning for the succession occupied his final decade. Rather than name a single heir, he divided responsibilities among his three surviving sons and two nephews, each assigned a territory as Caesar. The arrangement did not survive him: within months of his death, the army murdered most of his wider family, leaving only his sons in power ^[2].

In early 337 Constantine fell ill while preparing a campaign against Persia. He sought treatment at hot springs, then withdrew to a suburb of Nicomedia. There, only weeks before his death, he was baptized by the bishop Eusebius of Nicomedia. Delaying baptism until the deathbed was not unusual in the fourth century, since the rite was believed to cleanse all prior sin ^[3]. He died on May 22, 337, and was buried in Constantinople in the Church of the Holy Apostles, in a sarcophagus surrounded by memorials to the twelve apostles ^[4].

Anyone asking who was Constantine the Great is really asking how the Roman Empire became Christian, because the two stories are inseparable. At his accession Christians were a persecuted minority, perhaps a tenth of the population. By the end of the century Christianity was the official religion of the state. Constantine did not compel conversion, and pagan worship remained legal throughout his reign, but his patronage, legislation, and example moved the empire's center of religious gravity permanently ^[4]. The Orthodox churches venerate him as a saint and call him 'equal to the apostles.'

His city proved just as durable. Constantinople outlasted the western empire by nearly a millennium, preserving Roman law, Greek learning, and Christian institutions until the Ottoman conquest of 1453. The administrative and monetary structures he built, from the solidus to the reformed field army, gave the eastern empire the resilience that the West lacked ^[5].

Constantine's reputation has been argued over since his own lifetime. Eusebius of Caesarea presented him as God's chosen instrument; the pagan historian Zosimus blamed him for the empire's decline; Enlightenment writers, including Edward Gibbon, questioned the sincerity of his faith ^[6]. Modern scholarship generally accepts that his Christian commitment was genuine, if entangled with power and shaped by the assumptions of a Roman soldier. A forged medieval document, the Donation of Constantine, later claimed he had granted the western empire to the pope, an invention exposed by Lorenzo Valla in 1440 but influential for centuries ^[6]. That so many ages felt compelled to reinvent him is itself a measure of his weight: any Constantine the Great biography is also a history of how Europe explains its own origins.