Augustus vs Theodosius I

Octavian, Mark Antony, and Marcus Aemilius Lepidus formed the Second Triumvirate, a legal commission to govern the Roman Republic. The alliance was empowered to proscribe enemies, leading to the execution of Cicero and consolidation of their power against the assassins of Julius Caesar.

Octavian's fleet, commanded by Marcus Agrippa, defeated the combined naval forces of Mark Antony and Cleopatra VII off the coast of Greece. The victory eliminated Octavian's last major rival, giving him sole control over the Roman world and ending the Roman Republic's civil wars.

Octavian formally returned power to the Roman Senate, which then granted him the titles Augustus and Princeps. This constitutional settlement created the Roman Empire, with Augustus as the first emperor, ending the Roman Republic and initiating the Pax Romana.

Augustus implemented a comprehensive tax reform, including a census of Roman citizens and property, direct taxation of provinces, and the creation of a professional tax collection service (publicani). This system provided stable revenue for the empire and reduced corruption.

Augustus established the Praetorian Guard as a permanent elite military unit tasked with protecting the emperor and his family. Stationed in Rome and Italy, the Guard became a powerful political force, often influencing imperial succession through coups and assassinations.

The Roman Senate commissioned the Ara Pacis Augustae (Altar of Augustan Peace) to commemorate Augustus's return from pacifying Gaul and Spain. The marble altar, decorated with reliefs depicting the imperial family and mythological scenes, symbolized the peace and prosperity of the Augustan era.

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.