Constantine I the Great Biography and Timeline

Birth of Constantine I the Great

Constantine I is born at Naissus, probably in 272 or 273, to Constantius Chlorus and Helena.

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Raised at Eastern Court

As a young man, Constantine spends substantial time at the eastern imperial court, where he gains military and administrative experience.

Persian Campaign Service

Constantine serves as a staff officer during Galerius's Persian campaign while attached to the eastern imperial court.

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Marriage to Minervina

Constantine forms a union with Minervina, the mother of his eldest son Crispus.

Service with Diocletian in Egypt

Constantine accompanies Emperor Diocletian in Egypt while continuing his military and court service in the eastern empire.

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Witnesses Great Persecution

While attached to the eastern court, Constantine witnesses the beginning of Diocletian's persecution of Christians.

Joins Constantius in the West

Constantine leaves the eastern court and joins his father Constantius in the western provinces.

Succession

After Constantius I dies at York, his troops acclaim Constantine; Galerius subsequently recognizes him within the imperial system as Caesar.

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Campaign in Northern Britain

Constantine campaigns in northern Britain alongside Constantius during his father's final military expedition.

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Marriage to Fausta

Constantine marries Fausta, the daughter of the retired emperor Maximian, strengthening his political alliance with Maximian.

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Recognized as Augustus by Maximian

Maximian recognizes Constantine as Augustus during their alliance, although other tetrarchic rulers do not immediately accept the higher rank.

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Rule of Gaul and Britain

Constantine exercises effective authority in Gaul and Britain while the tetrarchic succession remains contested.

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Capture of Maximian

Constantine besieges Maximian at Massilia and takes him prisoner after the city's defenders open their gates.

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Maximian Rebellion

Maximian attempts to seize power while Constantine is campaigning, forcing Constantine to return rapidly to Gaul.

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Rhine Bridge at Cologne

Constantine completes a permanent bridge across the Rhine at Cologne to support military operations and frontier control.

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Battle of Milvian Bridge

Constantine defeats Maxentius at the Battle of the Milvian Bridge and becomes the dominant ruler in the western Roman Empire.

Entry into Rome

Constantine enters Rome after defeating Maxentius and is welcomed as the victorious western emperor.

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Praetorian Guard Disbanded

Constantine disbands the Praetorian Guard after its support for Maxentius and dismantles its military camp in Rome.

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Vision before Milvian Bridge

Christian sources later report that Constantine experienced a religious vision before his decisive campaign against Maxentius.

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Battle of Turin

Constantine defeats Maxentian cavalry near Turin and continues his advance across northern Italy.

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Battle of Verona

Constantine defeats forces loyal to Maxentius at Verona, removing a major obstacle on the road toward Rome.

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Capture of Segusium

Constantine captures Segusium after encountering resistance during his advance into northern Italy.

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Crossing of the Alps

Constantine crosses the Alps with his army to begin the Italian campaign against Maxentius.

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Alliance with Licinius

Constantine strengthens his alliance with Licinius when Licinius marries Constantine's half-sister Constantia at Milan.

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Edict of Milan

Constantine and Licinius agree at Milan on a policy of religious toleration and restoration of confiscated Christian property.

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Restoration of Christian Property

The Milan settlement provides for confiscated Christian meeting places and other property to be restored to Christian communities.

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Council of Arles

Constantine summons western bishops to the Council of Arles to address the Donatist dispute in North Africa.

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Arch of Constantine

The Arch of Constantine is dedicated in Rome to commemorate Constantine's victory over Maxentius.

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Fourth Consulship

Constantine serves his fourth consulship while consolidating authority in the western empire.

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Battle of Cibalae

Constantine defeats Licinius at Cibalae during the first civil war between the two emperors.

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Battle of Mardia

During the first war with Licinius, Constantine wins another engagement near Mardia after his victory at Cibalae.

Sons Made Caesars

Constantine II and Crispus are proclaimed Caesars alongside Licinius Junior under the peace settlement between Constantine and Licinius.

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Peace Settlement with Licinius

The peace settlement after the first civil war transfers extensive Balkan territories to Constantine while Licinius retains Thrace and the eastern provinces.

Rule of Illyricum

The settlement with Licinius gives Constantine control over most of Illyricum and strengthens his position in the Balkans.

Observance-Sundays

Constantine orders judges, urban populations, and many trades to rest on the venerable day of the Sun, establishing an empire-wide Sunday rest law.

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Sarmatian Campaign

Constantine defeats Sarmatian forces on the Danube frontier during renewed military operations in the Balkans.

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Gothic Pursuit into Licinius Territory

Constantine pursues Gothic forces into territory claimed by Licinius, worsening tensions that lead to renewed civil war.

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Battle of Adrianople

Constantine defeats Licinius near Adrianople in the renewed civil war and forces him to withdraw toward Byzantium.

Battle of Chrysopolis

Constantine defeats Licinius at Chrysopolis, ending the final major military challenge to his sole rule.

Foundation of Constantinople

Constantine formally refounds Byzantium as Constantinople, beginning the development of his new imperial residence.

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