Alexios I Komnenos vs Theodosius I

Alexios I Komnenos was defeated by the Norman army under Robert Guiscard at Dyrrhachium. The Byzantine forces were routed, and Alexios barely escaped. This loss allowed the Normans to occupy much of the western Balkans, though Alexios later recovered some territory.

Alexios I implemented a series of reforms to restore Byzantine power. He reorganized the army by relying more on foreign mercenaries, reformed the currency (the hyperpyron), and granted tax exemptions to the Church. These measures stabilized the empire after decades of decline.

Alexios I sent envoys to Pope Urban II at the Council of Piacenza, requesting military aid against the Seljuk Turks. This appeal contributed to Urban's call for the First Crusade at the Council of Clermont later that year, initiating the Crusader movement.

Alexios I cooperated with the Crusader army to besiege and capture Nicaea from the Seljuk Turks. The city was surrendered to Byzantine control, and Alexios used the Crusaders to recover key territories in Anatolia, though tensions later arose over land claims.

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.