417 CE

Emperor Honorius forces his half-sister Galla Placidia into marriage to Constantius, his general (magister militum). He is appointed patricius and becomes a prominent member of the House of Theodosius. Pope Innocent I condemns Pelagianism, and excommunicates the ascetic Pelagius. Innocent I dies after a 16-year reign in which he has restored relations between the sees of Rome and Antioch, enforced celibacy of the clergy, and maintained the right of the bishop of Rome to judge appeals from other churches. Innocent is succeeded by Zosimus as the 41st pope.

Geopolitics & Diplomacy

Nulji becomes king of the Korean kingdom of Silla.source
The Visigoths are granted Aquitaine, and become allies (foederati) of the Western Roman Empire. King Wallia establishes his capital at Toulouse.source

Conflict & Security

Exuperantius suppresses the Bagaudae Revolt in Armorica.source

Religion & Belief

January – Pope Innocent I condemns Pelagianism, and excommunicates the ascetic Pelagius.source

Culture & Society

January 1 – Emperor Honorius forces his half-sister Galla Placidia into marriage to Constantius, his general (magister militum). He is appointed patricius and becomes a prominent member of the House of Theodosius.source

Births

Justa Grata Honoria, daughter of Constantius III (approximate date)source
Peter the Iberian, Georgian theologian and Saint (approximate date)source

Deaths

March 12 – Innocent I dies after a 16-year reign in which he has restored relations between the sees of Rome and Antioch, enforced celibacy of the clergy, and maintained the right of the bishop of Rome to judge appeals from other churches. Innocent is succeeded by Zosimus as the 41st pope.source
Li Gao, Chinese general of the state Western Liang (b. 351)source
Yao Hong, last emperor of the Qiang state Later Qin (b. 388)source