Theodosius I vs Yi Seong-gye

Theodosius I issued the Edict of Thessalonica, declaring Nicene Christianity the official state religion of the Roman Empire. All other forms of Christianity were deemed heretical, and pagan practices were increasingly suppressed.

Theodosius I ordered a massacre of thousands of citizens in Thessalonica in retaliation for the murder of a Roman general. The massacre led to his excommunication by Bishop Ambrose of Milan, and he later performed public penance.

Theodosius I issued a series of laws banning pagan worship, closing temples, and prohibiting sacrifices. The Olympic Games were abolished, and the Serapeum in Alexandria was destroyed. These actions accelerated the decline of paganism in the empire.

Theodosius I defeated the usurper Eugenius and his general Arbogast at the Battle of the Frigidus (modern River Vipava). The victory reunited the Roman Empire under a single ruler for the last time before its permanent division.

Upon his death, Theodosius I divided the Roman Empire between his two sons: Arcadius received the Eastern Empire and Honorius the Western Empire. This division became permanent, leading to the separate histories of the Byzantine and Western Roman Empires.

Yi Seong-gye led Goryeo forces against Japanese pirates (wokou) at the Battle of Hwangsan. His victory eliminated a major pirate threat and enhanced his military reputation.

Yi Seong-gye turned his army back at Wihwado Island rather than invade Ming China as ordered by the Goryeo court. This act of defiance led to a coup that eventually brought him to power.

Yi Seong-gye overthrew the Goryeo dynasty and founded the Joseon dynasty, becoming King Taejo. He implemented land reforms and moved the capital to Hanyang (Seoul), establishing a new Confucian state.