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 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: ). 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Octavian and his co-consul Quintus Pedius rescinded the law branding Antony and Lepidus as outlaws, and Octavian formed an alliance with Antony and Lepidus.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 ('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.
Heir to Caesar
In 44 BC, Octavian was studying and undergoing military training in Apollonia, Illyria, when his great-uncle Julius Caesar was made Rome's first ('dictator in perpetuity') in February, and then assassinated on the Ides of March (15 March). Octavian consulted with Caesar's loyal army officers stationed in Macedonia for advice on a course of action, and ultimately decided to sail to Italy to ascertain whether he had any potential political fortunes or security. Caesar had no living legitimate children under Roman law. His daughter Julia had died in 54 BC; his son Caesarion by Cleopatra was not recognized by Roman law and was not mentioned in his will. In the absence of sons, Caesar's will made Octavian his main heir with the condition that he take up Caesar's name. After landing at Lupiae near Brundisium in southern Italy, Octavian received a copy of the will, which made him heir to three-quarters of Caesar's estate. and , citing among others: ; ; ; . See also , , , , and . Quintus Pedius and Lucius Pinarius were the remaining heirs, likely the children of Caesar's elder sister. Octavian's mother Atia chose not to intervene, while his stepfather Philippus advised him against accepting Caesar's will and to live quietly instead, but Octavian ultimately accepted it on 8 May 44 BC.
Accepting the inheritance by appearing before the urban praetor, Octavian purported that he was adopted as Caesar's son, a legally spurious but politically powerful claim, and assumed his great-uncle's name Gaius Julius Caesar. Roman citizens adopted into a new family usually retained their old nomen in cognomen form (e.g. for one who had been an Octavius, for one who had been an Aemilius). Julius Caesar's will entitled Octavian to style himself as Gaius Julius Caesar Octavianus. There is no evidence that Octavian himself used the name , seeking to portray himself more closely as Caesar's son; however some of his contemporaries did refer to him as Octavianus, such as Cicero and his stepfather Philippus. Historians usually refer to the new Caesar as Octavian during the time between his adoption and his assumption of the name Augustus in 27 BC, to avoid confusing the dead dictator with his heir.
Octavian could not rely on his limited funds to make a successful entry into the upper echelons of the Roman political hierarchy. After a warm welcome by Caesar's soldiers at Brundisium, Octavian demanded a portion of the funds that were allotted by Caesar for the intended war against the Parthian Empire in the Middle East. This amounted to 700 million sesterces stored at Brundisium, the staging ground in Italy for military operations in the east. A later senatorial investigation into the disappearance of the public funds took no action against Octavian since he subsequently used that money to raise troops against the Senate's enemy Mark Antony. Octavian made another bold move in 44 BC when, without official permission, he appropriated the annual tribute that had been sent from Rome's province of Asia in the Near East to Italy.
Octavian began to bolster his personal forces with Caesar's veteran legionaries and with troops designated for the Parthian war, gathering support by emphasizing his status as heir to Caesar. On his march to Rome through Italy, Octavian's presence and newly acquired funds attracted many, winning over Caesar's former veterans stationed in Campania. By June, he had gathered an army of 3,000 loyal veterans, paying each a bonus of 500 , which was more than a legionary soldier earned after two years of service.
Growing tensions
Arriving in Rome on 6 May 44 BC, Octavian found consul Mark Antony, Caesar's former colleague, in an uneasy truce with the dictator's assassins. They had been granted a general amnesty on 17 March in an agreement that they would respect the magistracies installed and laws passed by Caesar to avoid the political turmoil of invalidating them. Soon afterwards, Antony succeeded in driving most of them out of Rome with an inflammatory eulogy at Caesar's funeral, mounting public opinion against the assassins.
Mark Antony was amassing political support, but Octavian still had the opportunity to rival him as the leading member of the faction supporting Caesar. Antony had lost the support of many Romans and supporters of Caesar when he initially opposed the motion to elevate Caesar to divine status. Antony refused to hand over the money due Octavian as Caesar's heir, possibly on grounds that it would take time to disentangle it from state funds, but also as a measure to delay Octavian from carrying out the popular provision in Caesar's will that promised the dispersal of 300 sesterces per capita to the urban plebs of Rome. As consul, Antony blocked the curiate assembly from hearing Octavian's petition to legitimize his supposed adoption by Caesar, Octavian's attempts to reinstate Caesar's golden throne for public view at games staged in April and June, and Octavian's attempts to have Caesar formally deified after a comet seen in July during games honoring Caesar (and Venus) was widely interpreted as a sign of his divinity. Despite Antony's obstructionist tactics, during Caesar's victory games Octavian was able to distribute some of the funds in Caesar's will and combine this with other personal finances to cover half of the promised payouts to the plebs, enhancing his popularity while damaging that of Antony.
During the summer of 44 BC, Octavian won the support of Caesarian veterans and also made common cause with those senators—many of whom were themselves former Caesarians—who perceived Antony as a threat to the state. Antony had lictors drag Octavian away from a trial hearing over the reinstatement of private property seized by Caesar in 49 BC, after which Octavian claimed Antony threatened his life as retribution for ensuring the plebs received their rightful dues. Caesar's veterans then convinced Antony to publicly reconcile with Octavian in the Temple of Jupiter Optimus Maximus. Following this abortive attempt at reconciliation, Antony's bellicose edicts against Brutus and Cassius alienated him from the moderate Caesarians in the Senate, who feared a renewed civil war. In September, Marcus Tullius Cicero, now a political ally of Octavian, began to attack Antony in a series of speeches portraying him as a threat to the republican order.
First conflict with Antony
With opinion in Rome turning against him and his year of consular power nearing its end, Antony attempted to pass a plebiscite that would assign him proconsular governorship over the strategic province of Cisalpine Gaul in northern Italy, rather than the province of Macedonia. Octavian meanwhile built up a private army in Italy by recruiting Caesarian veterans, and in early November entered Rome with this private force to challenge Antony. However, they vacated the city shortly afterwards, due to some veterans choosing to quit once it became clear they were involved in a Caesarian squabble rather than a revenge campaign against Caesar's assassins. Nevertheless, on 28 November Octavian won over two of Antony's legions with the enticing offer of monetary gain.