Flavius Valerius Constantinus, who would become Roman emperor Constantine I, was born on February 27, circa 280 (sources range from 272 to 284), in Naissus, Moesia (now Niš, Serbia). His father, Flavius Valerius Constantius, was an officer in the Roman army. Constantine’s mother, Helena, was from humble beginnings; it is unknown whether she was the wife or concubine of Constantius.
In 289, Constantine’s father left Helena to marry the stepdaughter of Maximian, the Western Roman emperor. Constantine’s father was elevated to deputy emperor under Maximian in 293. Constantine himself was sent to the court of Diocletian, the Eastern Roman emperor. There, Constantine was educated in Latin and Greek. He likely also witnessed the persecution of Christians.
In 305, following Maximian’s abdication, Constantine’s father became Emperor Constantius I. Constantine then joined his father on a military campaign and fought alongside him in Britain. The next year, Constantius died at Eboracum (now York). Constantine was declared emperor by his troops. To make the designation official, he began to fight for power. Constantine now became the Western Roman emperor. He soon used his power to address the status of Christians, issuing the Edict of Milan in 313. This proclamation legalized Christianity and allowed for freedom of worship throughout the empire.
Constantine continued to proclaim his adherence to Christianity, and his reign established influence over religious conflicts within the church. Not wanting questions about the divine nature of Christ to sow discord, Constantine summoned church officials to the Council of Nicaea in 325. Out of this came the Nicene Creed, which affirmed that Jesus was a divine being. While in power, Constantine issued reforms intended to strengthen his regime. One such reform was a reorganization of the army, which helped Constantine when he faced tribes such as the Visigoths and the Sarmatians.
Constantine was in Helenopolis, planning a campaign against Persia, when he fell ill. He set out to return to Constantinople, but grew worse and was forced to halt his journey. He had delayed his baptism—a common practice at the time—but now underwent the rite. Constantine died on May 22, 337, in Ancyrona, near Nicomedia, Bithynia, at the approximate age of 57. He was buried in Constantinople at the church of the Apostles.