Caesar's will named as his adopted heir an eighteen year old great-nephew, Gaius Octavius, whom historians call Octavian. Few expected him to matter. Within fifteen years he had beaten every rival, and he went on to rule for over four decades while insisting that he had restored the Republic. Understanding how he did it explains how the Roman Empire worked for the next two centuries.

From civil war to sole rule

In 43 BC Octavian, Caesar's general Mark Antony and Marcus Lepidus formed the Second Triumvirate, this time a legal board with power to make laws. They posted new proscription lists, and the orator Cicero was among those killed. They defeated Brutus and Cassius at Philippi in 42 BC. Then the partners fell out. Antony joined his fortunes to Cleopatra VII, queen of Egypt. At the sea battle of Actium, off western Greece, in 31 BC, Octavian's fleet defeated Antony and Cleopatra, who both took their own lives in Egypt the next year. Egypt became Octavian's personal possession, and its grain fed Rome.

A monarchy in republican dress

Octavian had seen what happened to his adoptive father, who flaunted his power. He chose another path. In 27 BC he announced that he was returning the state to the Senate and people. In return the Senate gave Octavian the name Augustus, meaning "revered," along with the provinces where most legions were stationed. Over the next years he took the powers of a tribune without holding the office, which gave him a veto and sacred status, and authority over provincial governors. Augustus called himself princeps, "first citizen," rather than king or dictator, and the system he created is called the Principate. Elections, consuls and the Senate carried on. But the man who controlled the armies, the treasury and the patronage made the real decisions.

Ancient writers saw through it. Tacitus, writing about a century later, observed that Augustus won over the soldiers with gifts, the people with cheap grain and everyone with the sweetness of peace, while drawing the functions of the Senate and the magistrates into his own hands. Yet many Romans, exhausted by twenty years of civil war, accepted the bargain willingly.

The Augustan peace

Augustus rebuilt temples, turned the army into a standing professional force with fixed terms of service and a retirement payment, and set up fire brigades and a police force for the city. Suetonius says Augustus could boast that he had found Rome "built of brick and left it in marble" (translated by J. C. Rolfe, 1914). His rule began the Pax Romana, the Roman Peace, about two centuries of relative peace inside the empire. Peace inside the frontiers did not mean peace at them: wars of conquest and harsh suppression of revolts continued, as in Judaea from AD 66 to 73.

The problem of succession

Because the Principate was officially not a monarchy, it had no law of succession. Augustus tried to keep power in his family and outlived several chosen heirs before settling on his stepson Tiberius. His dynasty, the Julio-Claudians, produced the capable Claudius and the notorious Caligula and Nero. When Nero died in AD 68 without an heir, rival armies proclaimed their own generals emperor, so that AD 69 is called the Year of the Four Emperors. Tacitus wrote that "the secret of the empire was now disclosed, that an emperor could be made elsewhere than at Rome" (Church and Brodribb). Vespasian, the winner, founded the Flavian dynasty.

From AD 96 to 180 the empire had a run of rulers later called the Five Good Emperors: Nerva, Trajan, Hadrian, Antoninus Pius and Marcus Aurelius. Each of the first four, lacking a son, adopted a capable adult as heir, a practice admirers praised as choosing the best man. Under Trajan the empire reached its greatest extent, in AD 117. Marcus broke the pattern by leaving power to his son Commodus, whose reign went badly.

Worked example: reading the Res Gestae

Near the end of his life Augustus wrote an account of his deeds, the Res Gestae, which was inscribed on bronze in Rome and copied onto temples in the provinces; the best surviving copy is on a temple wall in Ankara, Turkey. In it he claims that after ending the civil wars he transferred the state to the Senate and people, and that he held no more official power than his colleagues in each office, only greater standing. How should we read it? Apply the ideas above. Each claim is technically defensible: he did hold offices the Senate granted. But the text leaves out what mattered most: the loyalty of the legions, his vast private wealth and the deaths of his opponents. It is propaganda, and skilful propaganda, because it uses the language of the old Republic to describe a new monarchy. Watching for that pattern, real power dressed in familiar forms, is a habit worth carrying far beyond Rome.