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The rise of Constantine I "the Great" (c. 272–337 CE; reign 306–337 CE) occurred amidst the political instability of the later Roman Empire, following the collapse of Diocletian’s Tetrarchic system. Proclaimed emperor by his troops at Eboracum (York) in 306 CE after the death of his father, Constantius I Chlorus, Constantine engaged in nearly two decades of civil war against rival claimants. His victory at the Battle of the Milvian Bridge (October 28, 312 CE) over Maxentius (his Italian rival) was a decisive turning point, famously associated with his initial conversion or public support for Christianity. By defeating Licinius (his Eastern co-emperor) in 324 CE, Constantine became the sole ruler of the Roman world.
As sole emperor (324–337 CE), Constantine implemented reforms that fundamentally redirected the empire's political and religious trajectory. He refined Diocletian’s administrative framework, and overhauled the military by creating a mobile field army (comitatenses). His reign is landmark for the Edict of Milan (313 CE), a joint agreement with Licinius that legalized Christian worship and ended state-sponsored persecution. Additionally, he established Constantinople on the site of Byzantium as the new imperial capital; dedicated in 330 CE, it shifted the empire’s strategic and cultural focus toward the eastern Mediterranean.
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Circus of Maxentius, Spina
Maxentius
Circus of Maxentius, Towers and Starting Gates
Silver Largitio Dish with the Name of Licinius
Roman Emperor Constantius Chlorus
Roman Emperor Constantius II
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APA Style
Netchev, S. (2026, March 21). Roman Empire under Constantine, 306-337 CE: From Civil War to Christian Rule. World History Encyclopedia. https://www.worldhistory.org/image/19366/roman-empire-under-constantine-306-337-ce/
Chicago Style
Netchev, Simeon. "Roman Empire under Constantine, 306-337 CE: From Civil War to Christian Rule." World History Encyclopedia, March 21, 2026. https://www.worldhistory.org/image/19366/roman-empire-under-constantine-306-337-ce/.
MLA Style
Netchev, Simeon. "Roman Empire under Constantine, 306-337 CE: From Civil War to Christian Rule." World History Encyclopedia, 21 Mar 2026, https://www.worldhistory.org/image/19366/roman-empire-under-constantine-306-337-ce/.
