List of 380 Major News Events in History, Most Important Historical Events in 380
| Date | Event |
|---|---|
| February 27, 380 | Edict of Thessalonica: Emperor Theodosius I and his co-emperors Gratian and Valentinian II declare their wish that all Roman citizens convert to Nicene Christianity. |
| November 24, 380 | Theodosius I makes his adventus, or formal entry, into Constantinople. |