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272
Constantine is born
Constantine is born Flavius Valerius Constantinus in the city of Naissus around February 27, 272. His father, Flavius Constantius, is a skilled politician, soldier, and bodyguard to Emperor Aurelian. His mother, Helena, is of low social rank. -
293
Constantius is made Caesar under Emperor Diocletian
By 293, the empire is ruled by two co-emperors, called Augustus, and each has two junior rulers under them, called Caesar. Diocletian, the eastern Augustus, appoints Constantine's father, Constantius, to Caesar on March 1 and immediately sends him off to battle rebels in Gaul. This sets up Constantine as Constantius's heir to the role of Caesar. -
303
Constantine witnesses the "Great Persecution."
In 303, Constantine returns from an eastern military campaign to Nicomedia in time to witness Diocletian executing the "Great Persecution." -
305
Diocletian and Galerius concurrently abdicate as emperors
Due to sickness and political pressure, both Diocletian and Galerius abdicate their roles as Augusti on May 1, 305. Galerius is named Augustus in the east, and Constantine's father, Constantius, is named Augustus in the west. Constantine is forced to flee to his father's protection to avoid becoming a hostage in Galerius's court. -
306
Constantius dies
After fleeing Galerius, Constantine joins his father on campaign in Britain. However, his father falls sick during the campaign and dies on July 25, 306. He names Constantine his heir as Augustus, and Gaul and Britain support his rule - though Iberia, which has only recently been conquered, does not. Galerius is outraged by the news, but he is forced to compromise and grants him the title of Caesar. Constantine accepts to solidify his claim. He is granted control over Britain, Gaul, and Spain. -
311
Galerius ends the persecutions of Christians
Galerius falls ill in 311, and as his last act in power, sends a letter that restores religious freedom to Christians. However, he soon dies thereafter. This sets off a war between Constantine and Maxentius, who barricades himself in Rome. -
311
Constantine takes the sigil of the Christian cross in battle
Maxentius, still in Rome, finds himself politically unpopular and worries that he won't be able to defeat Constantine during a long siege. He marches north to meet him at the Battle of the Milyain Bridge, during which Constantine's forces famously take on the sigil of the Christian cross. This signals his conversion to Christianity. Constantine defeats Maxentius, who is killed in the battle, and enters Rome to great celebration. The Senate names him Augustus. -
312
Constantine agrees to the Edict of Milan
Constantine moves to solidify his power and meets with one of his few remaining rivals, Licinius, in February 313. Licinius agrees to marry Constantine's half-sister, Constantia, and both men agree to the Edict of Milan, which grants full tolerance to Christianity and all other religions in the Empire. -
325
Constantine begins the First Council of Nicea
Constantine calls the First Council of Nicea, in what is modern day Turkey, on May 20, 325. He hopes to unify Christian doctrine, particularly around the issue of Arianism, or the question of whether Jesus is superior or equal to God. The influential Nicene Creed is formed. -
329
Constantine renames Byzantium Constantinople
After defeating Licinius, Constantine signals the shift from the old Greek and pagan ways to the Roman and Christian powers, and he moves his capital to finalize the change. After considering many different cities for the new capital, he chooses Byzantium for its logistical and strategic importance and renames it Constantinople. This signals the shift of the Roman Empire towards the East. -
337
Constantine dies
After solidifying the empire and instituting political and economic reforms, Constantine is finally baptized as a Christian shortly before dying on May 22, 337. He is buried in Constantinople and succeeded by his son from Fausta, Constantine II