|Constantine the Great|
Colossal head of Constantine (4th century), Capitoline museum, Rome
|Emperor of the Roman Empire|
|Predecessor||Constantius I (with Galerius in the East)|
|Reign||19 September 324 – 22 May 337 (emperor of whole empire)|
|Born||27 February c. 272|
Naissus, Moesia Superior, Roman Empire
|Died||22 May 337 (aged 65)|
Nicomedia, Bithynia, Roman Empire
Saint Constantine the Great
Mosaics in the Hagia Sophia, section: Maria as patron saint of Istanbul, detail: Emperor Constantine I with a model of the city
|Emperor, Confessor and Equal to the Apostles|
|Major shrine||Church of the Holy Apostles, Constantinople modern day Istanbul, Turkey|
Constantine the Great (Latin: Flavius Valerius Aurelius Constantinus Augustus; Ancient Greek: Κωνσταντῖνος ὁ Μέγας, romanized: Kōnstantînos ho Mégas; 27 February c. 272 AD – 22 May 337 AD), also known as Constantine I, was a Roman Emperor who ruled between 306 and 337 AD. Born in Naissus, in Dacia Ripensis, city now known as Niš (Serbian Cyrillic: Ниш, located in Serbia), he was the son of Flavius Valerius Constantius, a Roman Army officer of Illyrian origins. His mother Helena was Greek. His father became Caesar, the deputy emperor in the west, in 293 AD. Constantine was sent east, where he rose through the ranks to become a military tribune under 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 (Britain). Constantine was acclaimed as emperor by the army at Eboracum (modern-day York) after his father's death in 306 AD. He emerged victorious in a series of civil wars against Emperors Maxentius and Licinius to become sole ruler of both west and east by 324 AD.
As emperor, Constantine enacted administrative, financial, social, and military reforms to strengthen the empire. He restructured the government, separating civil and military authorities. To combat inflation he introduced the solidus, a new gold coin that became the standard for Byzantine and European currencies for more than a thousand years. The Roman army was reorganised 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 was the first Roman emperor to convert to Christianity.[notes 1] Although he lived much of his life as a pagan, and later as a catechumen, he joined the Christian faith on his deathbed, being baptised by Eusebius of Nicomedia. He played an influential role in the proclamation of the Edict of Milan in 313, which declared