The Second Triumvirate, to avenge Julius Caesar's murder, initiates the Liberator’s civil war, fought by the forces of Mark Antony and Octavian (who, with Lepidus, form the Second Triumvirate) against the forces of Caesar's assassins Brutus and Cassius in 42 BCE.

The result is death for Brutus and Cassius and victory for the triumvirs at the battle of Philippi; the Roman Republic, under the leadership of the triumvirs, reinstates control over the eastern provinces.

Caesar, after ensuring victory in his civil war, had planned a campaign into the Parthian Empire in 44 BCE to avenge the earlier defeat of a Roman army led by Marcus Licinius Crassus at the Battle of Carrhae.

Caesar's plan had been, after a brief pacification of Dacia, to continue east into Parthian territory.

Caesarian rule over the Republic had been effectively ensured by the defeat of Caesar's assassins at the Battle of Philippi.

Shortly after, however, with the triumvirs preoccupied with the revolt of Sextus Pompey in Sicily, Parthia attacks Roman-controlled Syria and the client kingdom of Judea.

The Judean high priest and puppet Roman ruler, Hyrcanus II, is overthrown and sent as prisoner to Seleucia, and the pro-Parthian Hasmonean Antigonus is installed in his place.

Antigonus is the only remaining son of former king Aristobulus II, who the Romans had deposed when they installed the weaker Hyrcanus II as high priest (but not king) in 63 BCE.

Antigonus, upon capturing Hyrcanus II, bites off his uncle's ears to disqualify him from ever again serving as high priest.

The Parthians ally with Quintus Labienus, son of Caesar's former general and later antagonist Titus Labienus, penetrating deep into the western Anatolia and defeating a Roman army under Decidius Saxa.

They are, however, defeated in turn by a veteran army led by Publius Ventidius Bassus, who drives the invaders from Roman territory.

Herod, the son-in-law of Hyrcanus, returns in 37 BCE to Judea with the aid of Mark Antony, Triumvir and lover of Egyptian Ptolemaic Queen Cleopatra VII, and recaptures Jerusalem.

The Sicilian revolt ends the following year in a Triumvirate victory.

Antony now goes on to attack the Parthian Empire itself, marching into Atropatene (present-day Iranian Azerbaijan) with some one hundred thousand legionaries, aided by the Roman client kings in Armenia, Galatia, Cappadocia and sovereign Pontus.

The campaign proves a disaster, however, after a Roman slip-up at Phraaspa, capital of Atropatene, and thousands of Romans and auxiliaries die during the retreat due to the cold winter.

Antony’s army loses more than a quarter of its strength in the course of the campaign.

Antony invades Armenia, gain with Egyptian money, this time successfully.

On his return in 34 BCE, a mock Roman Triumph is celebrated in the streets of Alexandria: the parade through the city is a pastiche of Rome's most important military celebration.

The whole city is summoned for the finale to hear a very important political statement by Antony, who, surrounded by Cleopatra and her children, ends his alliance with Octavian.

Julius Caesar, after a four-year-long politico-military struggle waged in Italy, Albania, Greece, Egypt, Africa, and Hispania, defeats the last of the Optimates in the Battle of Munda and becomes Dictator perpetuo (Perpetual Dictator) of Rome.

The changes to Roman government concomitant to the war mostly eliminate the political traditions of the Roman Republic (509–27 BCE) and lead to the Roman Empire (27 BCE–CE 476).

Caesar’s subsequent assassination in 45 BCE by the next generation of statesmen, led by Marcus Junius Brutus and Gaius Cassius Longinus, begins the process that eventually leads to the end of the Roman Republic with the reign of his great-nephew, Octavian (later known as Augustus).

The Senate's army (led first by Cicero and then by Octavian) wars with the army of Marcus Antonius (Mark Antony), Marcus Lepidus, and their colleagues.

The Post-Caesarian War culminates in the Battle of Mutina, fought on April 21, 43 BCE, between the forces of Antony and the forces of Gaius Vibius Pansa Caetronianus and Aulus Hirtius, who are providing aid to Decimus Junius Brutus Albinus.

It is a tactical victory for the Republican forces but a strategic victory for Antony, in that he is able to prevent encirclement of his forces and the enemy consul is killed; Octavian and the Republic sign a treaty with Antony and their forces unite.

Mediterranean Southwest Europe (45–34 BCE): Caesar's Consolidation and the End of the Republic

The era 45–34 BCE is pivotal in Roman history, characterized by the consolidation of Julius Caesar’s power and the definitive end of the Roman Republic. This period witnesses Caesar's establishment of unprecedented authority, his assassination, and the subsequent turmoil marking Rome’s transition to imperial governance.

Caesar’s Final Triumphs and Dictatorship for Life

By 45 BCE, Julius Caesar has decisively defeated the remaining senatorial opposition at the Battle of Munda in Hispania, effectively ending the lingering civil war. Caesar’s victory at Munda is notably challenging, and upon his return to Rome, he further solidifies his power by assuming the title dictator perpetuo (dictator for life) in early 44 BCE. This unprecedented move symbolizes the irreversible shift away from the traditional republican model toward autocratic rule.

Caesar undertakes significant administrative reforms, including the recalibration of the Roman calendar—the introduction of the Julian calendar—a major legacy that persists through millennia. He initiates extensive public works, urban renewal in Rome, and large-scale colonization projects, settling veterans and the urban poor in new provincial colonies.

Caesar's Assassination and the Ides of March

Caesar's increasing dominance, however, fuels resentment among senators who view his power as monarchical and antithetical to republican ideals. On the Ides of March (March 15), 44 BCE, Caesar is assassinated by a group of senators led by Marcus Junius Brutus and Gaius Cassius Longinus. The conspirators’ attempt to restore the Republic ironically plunges Rome into further civil war and political instability.

Aftermath and Power Struggle

Following Caesar's assassination, Rome quickly descends into chaos. Initially, public opinion in Rome turns against the conspirators, partly influenced by a stirring funeral oration by Caesar’s ally, Mark Antony, who skillfully sways public sentiment to outrage against the assassins. The conspirators flee Rome as Antony takes control.

Yet Antony’s dominance is quickly challenged. Caesar's adopted heir, the eighteen-year-old Octavian (later Augustus), arrives in Rome to claim his inheritance and political legacy. Despite initial cooperation against Caesar's assassins, Antony and Octavian soon become rivals, each vying for dominance.

Formation of the Second Triumvirate

By 43 BCE, political necessity drives Octavian and Antony, along with Marcus Aemilius Lepidus, to form the Second Triumvirate—a legally sanctioned political alliance. Unlike Caesar’s earlier informal First Triumvirate with Pompey and Crassus, the Second Triumvirate holds official constitutional status, explicitly empowered to rule Rome and reorganize the state.

The triumvirs swiftly proceed with a brutal proscription—a sanctioned purge against their political opponents, resulting in thousands of deaths, including that of the famed orator Marcus Tullius Cicero, whose opposition to Antony proves fatal.

Battle of Philippi and Defeat of the Conspirators

In 42 BCE, Antony and Octavian decisively confront Brutus and Cassius at the Battle of Philippi in Macedonia. The victory over the conspirators solidifies the triumvirate’s rule, effectively ending the republican cause. Brutus and Cassius both commit suicide following their defeat, symbolically marking the death of the republican ideal they had hoped to restore.

Division of Roman Territories and Rising Tensions

The triumvirs subsequently divide Roman territories among themselves. Antony takes control of the East, including Egypt, where he establishes a significant personal and political alliance with Cleopatra VII—an echo of Caesar’s earlier involvement. Octavian governs the western provinces, while Lepidus administers Africa. Despite this arrangement, mutual distrust and ambition sow seeds for future conflicts.

Legacy of the Era

The era 45–34 BCE definitively concludes the Roman Republic’s existence, initiating a complex and violent transition toward imperial rule. Caesar's death does not revive republican governance but instead plunges Rome into further civil war and political reconfiguration. The power struggles and political rearrangements following his assassination inexorably move Rome toward the establishment of imperial authority under Octavian, who will later emerge as Augustus, Rome's first emperor.

The Perusine War, a civil war of the Roman Republic that begins in 41 BCE, is fought by Mark Antony’s wife Fulvia and younger brother Lucius Antonius to support Antony against his political enemy (and the future Emperor Augustus), Octavian.

Fulvia dies in 40 BCE, and with her death comes a peace between Antony and Octavian.

The peace will be short-lived, however: civil war will begin a few years later.

Atlantic West Europe (45–34 BCE): From Caesar’s Aftermath to Augustan Stabilization

Between 45 and 34 BCE, Atlantic West Europe—including Aquitaine, the Atlantic coast, northern and central France, Alsace, and the Low Countries—underwent critical transformations, as the collapse of the Roman Republic transitioned into the early stability of Augustus’s Principate.

Political and Military Developments

Consolidation after Caesar’s Conquests

• Following Julius Caesar's assassination (44 BCE), uncertainty briefly gripped Roman Gaul. Local tribes in Aquitaine, the Loire Valley, and Belgica sought opportunities to reassert independence or renegotiate terms with Rome.

• Mark Antony's subordinate, Marcus Aemilius Lepidus, and Octavian swiftly reinforced Roman control in Gaul through diplomacy and military intimidation, stabilizing the region.

Regional Reorganizations under Octavian

• Octavian began administrative reorganizations, strengthening Roman rule by establishing coloniae (Roman settlements) and military veterans’ communities, particularly along strategic points such as Narbo (Narbonne) and Burdigala (Bordeaux).

• Local Celtic aristocrats were co-opted into Roman administration, solidifying loyalty among tribal elites.

Economic and Social Developments

Infrastructure and Urban Growth

• Roman infrastructure projects (roads, aqueducts, early towns) accelerated, enhancing economic integration. Aquitaine's developing wine industry increasingly fed markets in Italy and elsewhere in the Roman world.

• New trade networks emerged, bolstered by stable Roman authority, connecting Atlantic ports such as Bordeaux and Nantes to Mediterranean and northern European routes.

Cultural and Social Integration

• Local elites began to adopt Roman customs, including Latin language and urban lifestyles, leading to an early form of Gallo-Roman cultural identity.

• Roman colonization and settlement increased urbanization, as Roman veterans and merchants settled in strategic locations throughout the region.

Cultural and Religious Developments

Early Romanization and Religious Syncretism

• The Roman presence fostered religious syncretism, combining Celtic and Roman deities. Roman gods like Mercury and Mars became associated with local deities in places such as Lutetia (Paris) and Avaricum (Bourges).

• Druids maintained significant influence, but Roman political authorities viewed them as potential sources of unrest, marking the beginning of gradual suppression.

Key Figures and Events

• Octavian (future Augustus): Initiated policies that brought stability to the region after initial uncertainty following Caesar’s death.

• Marcus Agrippa: Conducted infrastructure improvements and pacification efforts, particularly around strategic Atlantic centers.

Long-Term Significance

By 34 BCE, Atlantic West Europe was firmly on the path toward full integration into the Roman Empire:

• Roman rule and administrative reforms created stability after initial turmoil.

• Roman cultural influence took root among local elites, paving the way for deeper Romanization.

• Economic developments, especially in Aquitaine and along the Atlantic coast, laid the groundwork for long-term prosperity under imperial rule.

This era thus marked the pivotal transition from Republican instability to the establishment of enduring Roman control and cultural integration in Atlantic West Europe.

Publius Cornelius Dolabella at Caesar's death in 44 BCE had seized the insignia of the consulship (which had already been conditionally promised him) and, by making friends with Marcus Junius Brutus and the other assassins, had been confirmed in his office.

When, however, Mark Antony had offered him the command of the expedition against the Parthians and the province of Syria, he had changed sides at once.

His journey to the province is marked by plundering, extortion, and the murder of Gaius Trebonius, proconsul of Asia, who had refused to allow him to enter Smyrna.

Dolabella is thereupon declared a public enemy and superseded by Gaius Cassius Longinus, who had been a principal among Casear’s forty-odd assassins.

Cassius attacks Dolabella in Laodicea.

Strabo mentions that Dolabella, when he fled to Laodicea before Cassius, had distressed Laodicea greatly, and that, being besieged there until his death, he had destroyed many parts of the city with him.

When Cassius's troops capture the place, Dolabella orders one of his soldiers to kill him.

Cassius is now secure enough to march on Egypt, but Brutus requests his assistance upon the formation of the new triumvirate of Marcus Aemilius Lepidus, Mark Antony, and Octavian,.

Cassius quickly joins Brutus in Smyrna with most of his army, leaving his nephew behind to govern Syria.

The conspirators decide to attack the triumvir’s allies in Asia.

Brutus ravages Lycia.

Appian, Dio Cassius, and Plutarch each report that the city of Xanthos is once again destroyed. (Appian will note that it was rebuilt under Mark Antony).

Patara, captured also, is spared the massacres inflicted on nearby Xanthos.

Both cities, together with Pinara, Tlos, Olympos, and Phaselis, are members of the Lycian League, of which …

…Myra is the largest member, although Patara serves as the league’s capital.