Rise of Augustus

The rise of Augustus, the first Roman emperor, covers his life from his gathering of legions loyal to Roman dictator Julius Caesar in Roman Italy in 44 BC, following Caesar's assassination on the Ides of March (15 March), until the Roman Senate's bestowal upon him of the title augustus in 27 BC. The latter date marks the traditional end of the Roman Republic and beginning of the Roman Empire. Augustus was born Gaius Octavius in 63 BC and is known during this phase of his life as Octavian (Latin: Octavianus). The period between 44 and 27 BC witnessed the formation of the Second Triumvirate by Octavian, Mark Antony, and Marcus Aemilius Lepidus, and the eventual fissure of this triple dictatorship as Octavian ultimately defeated his rivals.

Caesar's former general Mark Antony served as consul in an erstwhile uneasy truce with Caesar's assassins, until the flight of the assassins from the city of Rome and Octavian's arrival in the city. Antony attempted to thwart Octavian's oversight of games dedicated to Caesar and his inheritance outlined in Caesar's will, but Octavian successfully outmaneuvered Antony by distributing money promised by Caesar to the plebs. While Antony fought Decimus Junius Brutus Albinus in the War of Mutina in Cisalpine Gaul during early 43 BC, the senator Marcus Tullius Cicero attempted to groom Octavian as his protege for public office, having him inducted into the Senate at a young age on account of his private army that could be used to oppose Antony. However, after the siege of Mutina was lifted and Antony retreated north in defeat, Octavian refused to cooperate with the Senate and demanded the consulship. When this was refused he marched on Rome in August 43 BC, had his army occupy the Campus Martius, and was elected as Rome's youngest consul.

Octavian and his co-consul Quintus Pedius rescinded the law branding Antony and Lepidus as outlaws, and Octavian formed an alliance with Antony and Lepidus. The lex Titia passed by plebeian tribune Publius Titius in November 43 BC provided the legal framework for a new triumviral regime formed by Octavian, Antony, and Lepidus, who immediately enacted proscriptions that led to the outlawing, killing, and seizure of property of Caesar's assassins and their allies. At the Battle of Philippi in Roman Greece during October 42 BC Octavian and Antony prevailed against the anti-Caesarian forces led by Gaius Cassius Longinus and Marcus Junius Brutus. Octavian and Lepidus also eventually defeated Sextus Pompeius in Sicily after the latter had blockaded Italy and attempted to carve out a sphere of influence in the Mediterranean. Lepidus attempted to challenge Octavian in Sicily soon afterwards, but Octavian forced him to surrender and exiled him, though he was allowed to hold the prestigious position of pontifex maximus ('supreme pontiff').

Meanwhile, Antony allied himself with Cleopatra, Queen of Ptolemaic Egypt, Caesar's former lover. They married and had three children, and Antony relied on Cleopatra's financial support for military campaigns against the Parthian Empire and Kingdom of Armenia. Given Antony's rejection and divorce of Octavian's sister Octavia Minor, and planned implementation of the Donations of Alexandria that would grant Cleopatra and their children fiefs carved from Roman provincial territory, Octavian depicted Antony as a betrayer of Rome. In 32 BC he forced two consuls loyal to Antony and many senators to flee Rome after taking over the Senate chambers, convinced the remaining Senate to declare war on Cleopatra's regime, and had men across Italy swear an oath of allegiance to him as a mandate for leading the campaign. In 31 BC Octavian's naval forces led by Marcus Vipsanius Agrippa defeated those of Antony and Cleopatra at the Battle of Actium off the northwestern coast of Greece, and in 30 BC Octavian's forces invaded Alexandria and conquered Egypt. Octavian became the first Roman pharaoh of Egypt, and by 27 BC reached a formal settlement with the Senate for control over half of Rome's provinces and most of its armies, in effect becoming the first Roman emperor.