Late Roman Empire

The Roman Empire during its later centuries, especially from the third century to the fifth in the west and the fifteenth in the east. It was reshaped by administrative reforms, military pressures, and Christianity’s rise.

Crisis of the Third Century: A period of political instability, civil wars, invasions, and economic disruption in the Roman Empire from 235 to 284. This upheaval prompted reforms that reshaped the later empire.
Battle of Adrianople: A battle in 378 in which Gothic forces defeated and killed Emperor Valens near Adrianople. The defeat exposed limits in eastern imperial military leadership and settlement policy.
Diocletian: Roman emperor from 284 to 305 who introduced sweeping administrative and military reforms. His reforms established much of the later empire’s governing structure.
Fall of the Western Roman Empire: The end of imperial rule in the western provinces, conventionally dated to the deposition of Romulus Augustulus in 476. It marks the conventional endpoint of the western empire, not of Roman rule in the east.
Christianization of the Roman Empire: The gradual adoption of Christianity across Roman society and government from the first through the fourth centuries. Christian institutions and imperial policy became closely intertwined in this era.
Diocletianic Reforms: Administrative, military, and fiscal changes introduced under Emperor Diocletian in the late third century. They expanded imperial administration and reorganized taxation and defense.
Edict of Milan: A proclamation issued in 313 by Constantine and Licinius that granted religious toleration, including to Christians. It marked a major change in the empire’s treatment of Christianity.
Constantine the Great: Roman emperor from 306 to 337 who favored Christianity and founded Constantinople as an imperial capital. His policies transformed Christianity’s standing and redirected imperial power eastward.
Western Roman Empire: The western half of the Roman Empire, governed separately from the east for much of late antiquity until its imperial office ended in 476. Its weakening and political fragmentation define the period’s western trajectory.
Arianism: A Christian theological movement that rejected the Nicene claim that the Son is of the same substance as the Father. Its disputes divided communities and drew repeated intervention from Roman emperors.

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