Octavian
Gaius Octavius was born in Rome on 23 September 63 BC. His father — a wealthy equestrian politician — died when Octavius was four. His mother Atia was the niece of Julius Caesar. Caesar took an active interest in his great-nephew’s education from the early 50s BC and brought him on the Spanish campaign of 45 BC. When Caesar was assassinated on the Ides of March 44 BC, his will named Octavius — then 18 years old, in Apollonia in modern Albania — as his posthumous adopted son and the heir to three-quarters of his fortune.
Octavius arrived in Italy within weeks, took the name Gaius Julius Caesar Octavianus (Octavian, in standard English usage), and over the following thirteen years methodically destroyed every rival who stood between him and undisputed power in the Roman world.
The civil war
Octavian’s first political coalition was the Second Triumvirate of November 43 BC: a legally sanctioned three-man dictatorship shared with Mark Antony (Caesar’s senior surviving general) and Marcus Aemilius Lepidus (the pontifex maximus). The triumvirate’s first action was a programme of proscriptions — lists of political enemies marked for execution and property confiscation — that killed approximately 300 senators including, most famously, Cicero.
At the Battle of Philippi (October 42 BC) the triumvirate defeated the senate-aligned forces of Brutus and Cassius, who had organized Caesar’s assassination. Both committed suicide on the field. The triumvirate then divided the empire: Antony took the wealthy eastern provinces (Greece, Anatolia, Syria, and the Egyptian client kingdom of Cleopatra VII); Octavian took Italy and the west; Lepidus was given the secondary territory of North Africa and gradually marginalized.
The triumvirate dissolved through the 30s BC. Lepidus was forced into political retirement in 36 BC after attempting to seize Sicily. The break between Octavian and Antony — accelerated by Antony’s open marriage to Cleopatra and his redistribution of Roman eastern provinces to her children — led to formal civil war in 32 BC. The decisive engagement was the naval Battle of Actium (2 September 31 BC), off the western coast of Greece, at which Octavian’s fleet under his admiral Marcus Vipsanius Agrippa defeated the combined Antonian-Egyptian fleet. Antony and Cleopatra fled to Alexandria, where they killed themselves the following summer. Egypt — the last remaining major Hellenistic kingdom — was annexed by Rome as an imperial province in August 30 BC.
Octavian was 32. He controlled the entire Roman world.
The Augustan settlement
The political problem facing Octavian after Actium was the same problem Caesar had failed to solve: how to make permanent personal rule of the Roman state acceptable to the Roman political class, which still considered itself an aristocratic republican community and remembered the assassination of Caesar fourteen years earlier. Octavian’s answer was the Principate: a constitutional fiction in which he held no permanent royal title but accumulated the powers of all the major Republican offices simultaneously, while preserving the forms of senatorial government.
The decisive moment was the First Constitutional Settlement of 13–16 January 27 BC, at which Octavian formally returned all his powers to the Senate and the Roman people. The Senate, by carefully managed acclamation, returned them. Octavian took the new honorific title Augustus (“revered”) and the informal designation princeps (“first citizen”). He renounced the dictatorship and the consulship-for-life that Caesar had taken. He kept proconsular imperium maius (military command over the militarily critical provinces), tribunicia potestas (tribune’s power, the legal basis for veto and personal inviolability), and the pontifex maximus (chief priestly office). The arrangement was refined in subsequent settlements through 23 BC.
The compromise worked. Augustus ruled Rome for the next 41 years without serious political opposition. The Republican constitutional language was preserved — official documents continued to be dated by consulships — and the Senate continued to meet and legislate. The substantive reality was personal monarchy.
The reign
Augustus’s 41 years of rule (27 BC – 14 AD) produced the political reorganization of the Roman world that would persist for the next three centuries. He fixed the Roman boundaries at the Rhine, the Danube, and the Euphrates after a major eastern campaign and the disastrous loss of three legions in the Teutoburg Forest in 9 AD (the Varian Disaster). He created the professional standing Roman army, the praetorian guard, the imperial bureaucracy, the urban cohorts, the vigiles (Rome’s police and fire service), the imperial postal system, and the system of provincial administration that survived until Diocletian. He systematized Roman law, conducted the first comprehensive census of the empire (the one mentioned in the Gospel of Luke), and patronized the literary culture that produced Virgil, Horace, Ovid, and Livy.
He died at Nola in southern Italy on 19 August 14 AD, aged 75. The succession passed to his stepson and adopted son Tiberius. The principate Augustus had designed continued. Rome was a monarchy, and would remain one.
Legacy
Augustus’s reorganization of Roman government inaugurated the Pax Romana — the two centuries of relative internal peace and economic expansion across the Mediterranean that lasted until the death of Marcus Aurelius in 180 AD. The dynasty he founded (the Julio-Claudians) ruled Rome until the death of Nero in 68 AD. His month — the month of his birth was September, but the month renamed for him was August, originally Sextilis, because he had won his greatest victories in August. The title augustus became one of the standard imperial titles for the next millennium and is the source of the modern adjective.