The Roman Republic (509-27 BC)

The Roman nobility overthrows King Tarquinius Superbus and abolishes the monarchy. Lucius Junius Brutus and Lucius Tarquinius Collatinus are elected as the first consuls, establishing a republican government with annually elected magistrates and a senate.

Rome's plebeians (commoners) secede from the city to demand political rights from the patrician elite. The office of Tribune of the Plebs is created, giving plebeian representatives veto power over patrician magistrates and sacrosanctity from harm.

Rome publishes its first written law code, the Twelve Tables, on twelve bronze tablets displayed in the Forum. The code establishes legal equality before the law for patrician and plebeian and becomes the foundation of Roman jurisprudence.

Senone Gauls under the chieftain Brennus defeat the Roman army at the Battle of the Allia and sack Rome. The trauma of the sack spurs major military reforms and the construction of the Servian Wall to defend the city.

Rome defeats its Latin allies in the Latin War and dissolves the Latin League. Conquered Latin cities are incorporated into the Roman state through grants of citizenship and allied status, establishing the model for Roman territorial expansion.

Rome fights King Pyrrhus of Epirus, who came to aid the Greek city of Tarentum. Despite costly Pyrrhic victories using war elephants, Pyrrhus is ultimately defeated, and Rome extends its control over Magna Graecia (southern Italy).

Rome fights its first war outside Italy against Carthage for control of Sicily. Rome rapidly builds a navy and defeats Carthage at sea, annexing Sicily as its first provincia and becoming a Mediterranean naval power.

Hannibal Barca crosses the Alps with war elephants and inflicts devastating defeats on Rome at the Trebia, Lake Trasimene, and Cannae. Rome under Scipio Africanus ultimately invades North Africa and defeats Hannibal at the Battle of Zama (202 BC), establishing Roman hegemony over the western Mediterranean.

Rome besieges and utterly destroys Carthage in the Third Punic War. The same year, the Roman army sacks Corinth, completing the subjugation of Greece. The destruction of Carthage eliminates Rome's last rival in the Mediterranean.

Tiberius Gracchus, elected Tribune of the Plebs, proposes land reforms to redistribute public land to poor citizens. He is murdered by senators and their supporters. His brother Gaius Gracchus continues reform efforts but is also killed in political violence (121 BC), marking the start of the late Republic's era of civil strife.

Rome's Italian allies (socii) rebel over the denial of Roman citizenship in the Social War. After fierce fighting, Rome grants citizenship to all Italians south of the Po River to end the war, dramatically expanding the Roman citizen body and transforming the political landscape.

Lucius Cornelius Sulla marches on Rome, defeats his Marian rivals in a civil war, and has himself appointed dictator. He carries out proscriptions (executing thousands of political enemies) and enacts constitutional reforms to strengthen the Senate, then voluntarily retires in 79 BC.

Julius Caesar, Pompey the Great, and Marcus Licinius Crassus form the First Triumvirate, an informal political alliance that dominates the Roman state. Caesar secures command in Gaul, beginning a decade of conquest that makes him the wealthiest and most powerful figure in the Republic.

Over eight years, Caesar conquers Gaul, defeats Germanic tribes, and conducts the first Roman invasion of Britain. The campaigns are documented in Caesar's Commentarii de Bello Gallico. His military successes and vast wealth alarm his political opponents in the Senate.

Caesar crosses the Rubicon River with his army in defiance of the Senate's orders, triggering a civil war against Pompey and the optimates. Caesar defeats Pompey at Pharsalus (48 BC) and eventually secures sole control of the Roman state.

On the Ides of March (March 15), Julius Caesar is assassinated by a group of senators led by Marcus Junius Brutus and Gaius Cassius Longinus. The assassination plunges Rome into another round of civil wars that ultimately destroy the Republic.

Octavian, having defeated Mark Antony and Cleopatra at the Battle of Actium (31 BC), is granted the title Augustus by the Senate. This marks the traditional end of the Roman Republic and the beginning of the Roman Empire, as constitutional forms are maintained but power is concentrated in the emperor.