421 CE
Emperor Theodosius II marries Aelia Eudocia, a woman of Greek origin. The wedding is celebrated at Constantinople with chariot racing in the Hippodrome. Constantius III dies suddenly of an illness; his wife Galla Placidia becomes, for the second time, a widow. Roman–Sassanid War: Theodosius II starts a war against the Sassanids, sending an expeditionary force under command of Ardaburius, and invades Mesopotamia.
Conflict & Security
- Autumn – Ardaburius devastates Arzanene (Armenia) and forces the Persians to retreat to Nisibis (Syria). King Bahram V allies himself with the Lakhmid Arabs of Hirah.source
- Castinus campaign against the Franks: A Roman army under command of Castinus fights against the Franks in Northern Gaul.source
- Roman–Sassanid War: Theodosius II starts a war against the Sassanids, sending an expeditionary force under command of Ardaburius, and invades Mesopotamia.source
- Rugila, chieftain of the Huns, attacks the dioceses of Dacia and Thrace (Balkans). Theodosius II allows Pannonian Ostrogoths to settle in Thrace, to defend the Danube frontier.source
Exploration & Expansion
- The Franks conquer new territories in their kingdom and sack the old Roman capital Augusta Treverorum (modern Trier).source
Religion & Belief
- February 8 – Constantius III is appointed co-emperor (Augustus) with his ineffectual brother-in-law, Honorius, and becomes the real ruler of the Western Roman Empire.source
- March 25 – Venice is founded at twelve o'clock noon (according to legend) with the dedication of the first church, San Giacomo, at the islet of Rialto (Italy).source
Culture & Society
- June 7 – Emperor Theodosius II marries Aelia Eudocia, a woman of Greek origin. The wedding is celebrated at Constantinople with chariot racing in the Hippodrome.source
Deaths
- September 2 – Constantius III dies suddenly of an illness; his wife Galla Placidia becomes, for the second time, a widow.source
- September 2 – Constantius III, emperor of the Western Roman Empiresource
- Mary of Egypt, patron saint (approximate date)source
- Ravina I, rabbi (teacher) and Jewish Talmudistsource
- Jin Gongdi, last emperor of the Jin Dynasty (b. 386)source
- Li Xun, ruler of the Chinese state Western Liangsource