Julius Caesar was assassinated during a Senate meeting at the Curia of Pompey in Rome, an event that destabilized the state and triggered the final cycle of civil wars that ended the Roman Republic.
At Caesar’s funeral, Mark Antony’s oration helped turn public anger against the assassins, deepening polarization in Rome and making a negotiated restoration of the old republic increasingly unlikely.
Gaius Octavius (Octavian) returned to Italy to accept Caesar’s adoption and inheritance, positioning himself as a rival power-center to Antony and a focal point for Caesarian veterans and networks.
Forces aligned with the Senate (with the consuls and Octavian present) fought Antony near Forum Gallorum in northern Italy as part of the War of Mutina, temporarily strengthening the Senate’s hand against Antony.
At Mutina (near modern Modena), senatorial forces and Octavian defeated Antony’s army and forced his retreat, but the ensuing power vacuum and shifting loyalties soon undercut the Senate’s apparent victory.
Octavian, Antony, and Lepidus were legally empowered as triumviri rei publicae constituendae ("three men for restoring the Republic") by the Lex Titia, creating an extraordinary magistracy with sweeping authority.
Soon after the triumvirate’s legal formation, the triumvirs initiated proscriptions—state-sanctioned lists of enemies to be killed and dispossessed—both to eliminate opponents and to raise money for the coming war.
The orator and statesman Cicero—an emblematic opponent of Antony—was killed during the triumviral proscriptions, signaling the effective end of senatorial leadership capable of resisting the triumvirs by constitutional means.
In two major engagements near Philippi in Macedonia, Antony and Octavian defeated Brutus and Cassius, decisively crippling the main faction claiming to defend the pre-Caesarian republic.
Conflict in Italy (41–40 BCE) pitted Octavian against Lucius Antonius and Fulvia, reflecting mounting internal strains in the triumviral coalition and the destabilizing pressures of veteran settlement and political rivalry.
The triumvirs reached an agreement with Sextus Pompey (who controlled key western islands and threatened Rome’s grain supply), briefly easing the crisis before the settlement collapsed and war resumed.
Agrippa’s fleet, fighting for Octavian, defeated Sextus Pompey off Sicily, ending the most serious naval challenge to the triumvirate in the west and consolidating Octavian’s military and political position.
After the defeat of Sextus Pompey, Lepidus attempted to assert control in Sicily but was outmaneuvered; his troops defected and he was stripped of nearly all offices, leaving Octavian and Antony as the dominant rivals.
Antony and Cleopatra’s public "Donations of Alexandria" redistributed territories and titles in the east to Cleopatra’s children, providing Octavian with powerful propaganda that Antony was subordinating Roman interests to a foreign monarchy.
Octavian’s fleet, led by Agrippa, defeated the combined forces of Antony and Cleopatra off western Greece; the victory made Octavian the undisputed master of the Roman world and marked the decisive military end-point of the Republic’s collapse.
From Caesar's Assassination to Actium: The End of the Republic (44–31 BCE)
