Forces loyal to the Senate (with Octavian present in the senatorial camp) fought Mark Antony near Mutina, part of the escalating struggle over Caesar’s veterans and legitimacy after the Ides of March.
A second major engagement near Mutina forced Antony to retreat, briefly strengthening the Senate’s position—until Octavian broke with senatorial leadership and pursued power on his own terms.
Octavian, Mark Antony, and Lepidus met near Bononia (Bologna) and negotiated a power-sharing arrangement that included provincial divisions and the decision to use proscriptions—setting the stage for legalized extraordinary rule.
The lex Titia created a formal, extraordinary magistracy for Octavian, Antony, and Lepidus (tresviri rei publicae constituendae) with sweeping authority, marking a decisive constitutional break in the late Republic.
Soon after the triumvirate’s legal formation, the regime published proscription lists to eliminate opponents and finance war through confiscations; the terror reshaped elite politics and helped fund the coming campaign against the Liberators.
At Philippi in Macedonia, triumviral forces fought Brutus and Cassius; after the first battle, Cassius committed suicide, weakening the Liberators’ command structure.
A second engagement at Philippi ended the War of the Liberators: Brutus was defeated and took his own life, leaving the triumvirs dominant across the Roman world.
Conflict broke out between Octavian and Antony’s faction in Italy (centered on Lucius Antonius and Fulvia), reflecting tensions over land distributions and political control within the triumviral coalition.
Antony and Octavian reached a settlement at Brundisium, stabilizing their relationship and redividing spheres of influence; the agreement underpinned renewed cooperation amid wider conflicts, including Sextus Pompey’s pressure on Italy’s grain supply routes.
The triumvirs temporarily settled with Sextus Pompey—who controlled key maritime supply lines—granting him recognized territories and promises of office in return for ending his blockade/piracy and restoring grain shipments.
Antony and Octavian reached a new compact at Tarentum in 37 BCE, renewing the triumvirate’s arrangement for another five years and exchanging resources (notably ships for promised troops) as each prepared for major campaigns.
Agrippa’s fleet won a decisive victory over Sextus Pompey off Sicily, ending the last large-scale organized opposition to the triumvirate in the western Mediterranean and securing Rome’s grain supply routes.
After the Sicilian campaign, Lepidus attempted to assert authority in Sicily; Octavian used the ensuing confrontation to strip Lepidus of power and expel him from effective rule, leaving Octavian and Antony as the dominant rivals.
After fleeing the west, Sextus Pompey was ultimately caught in Asia Minor and executed, removing a persistent symbolic and military alternative to Caesarian rule and consolidating the post-Philippi order.
Second Triumvirate, Proscriptions, and the War of the Liberators (43–33 BCE)
