Augustus: First Roman Emperor and the Birth of the Principate

Augustus transformed Rome more profoundly than almost any other Roman ruler. Born Gaius Octavius in 63 BCE, he entered public life as the adopted heir of Julius Caesar and emerged from two decades of civil war as the uncontested master of the Roman world.

Yet Augustus did not present himself as a king or openly abolish the Republic. Instead, he built a new political system that preserved familiar offices and institutions while concentrating military, political and religious authority in his own hands. That settlement became the foundation of the Roman Empire. For the wider story, see our Ancient Rome hub.

Who was Augustus?

Augustus was born Gaius Octavius on 23 September 63 BCE. His family was wealthy and politically connected, though not among Rome’s oldest aristocratic houses. His mother, Atia, was a niece of Julius Caesar.

Caesar took an increasing interest in the young Octavius and named him his principal heir in his will. After Caesar’s assassination in 44 BCE, Octavius learned that he had also been adopted posthumously by Caesar and inherited much of his estate.

The eighteen-year-old heir now had a powerful name but very little direct political experience. What followed was one of the most remarkable rises to power in Roman history.

Octavian enters Roman politics

After Caesar’s death, Mark Antony initially appeared to be the strongest leader of the Caesarian faction. Octavian nevertheless returned to Italy and began claiming Caesar’s political legacy for himself.

He paid promised bequests from Caesar’s will, courted veterans and presented himself as Caesar’s legitimate son and heir. The name of Caesar carried enormous political weight, especially among soldiers and supporters who wanted revenge for the assassination.

Octavian also formed a temporary alliance with senators hostile to Antony. Cicero, in particular, hoped the young heir could be used against Antony and then politically controlled. That expectation proved badly mistaken.

The Battle of Mutina

In 43 BCE, senatorial forces and Octavian’s troops fought Antony near Mutina in northern Italy. Antony was forced to withdraw, but both serving consuls died during the campaign.

Octavian now commanded a substantial army. When the Senate resisted his political demands, he marched on Rome and secured election as consul despite being far younger than the normal age for the office.

Rather than continue fighting Antony, Octavian changed course and reached an agreement with him and Lepidus.

The Second Triumvirate

In November 43 BCE, Octavian, Antony and Lepidus formed the Second Triumvirate. Unlike the earlier informal alliance of Caesar, Pompey and Crassus, this triumvirate was legally established and granted extraordinary powers.

The triumvirs launched proscriptions against enemies and wealthy opponents. Property was confiscated and many people were killed. Cicero became one of the most famous victims.

In 42 BCE the triumvirs defeated Brutus and Cassius, two of Caesar’s leading assassins, at Philippi in Macedonia. The victory eliminated the strongest remaining military opposition associated with the republican cause.

The final decades of the Roman Republic were now dominated by men commanding armies and provinces on an extraordinary scale.

Octavian and Antony divide the Roman world

After Philippi, Antony became the dominant Roman authority in the East, while Octavian focused on the West. Lepidus gradually became less important.

Octavian faced serious challenges. He had to settle large numbers of veterans on Italian land, a process that created resentment and conflict. He also fought Sextus Pompey, the son of Pompey the Great, whose naval forces threatened Rome’s grain supply.

Marcus Agrippa, Octavian’s close friend and most important military commander, played a crucial role in defeating Sextus Pompey in 36 BCE.

The removal of Lepidus

After the defeat of Sextus Pompey, Lepidus attempted to strengthen his own position in Sicily. Octavian outmaneuvered him politically and won over his troops.

Lepidus was stripped of most of his power, although he retained the prestigious religious office of pontifex maximus until his death. The Roman world was now effectively divided between Octavian and Antony.

Antony, Cleopatra and the final civil war

Antony’s relationship with Cleopatra VII of Egypt became increasingly important politically as well as personally. Cleopatra supplied money, ships and access to the resources of Egypt, while Antony governed Rome’s eastern territories.

Octavian used Antony’s eastern alliances as propaganda, portraying his rival as a Roman leader who had abandoned Roman values for an Egyptian queen. The reality was more complicated: Antony remained deeply involved in Roman politics and commanded large Roman forces.

The rivalry is covered in more detail in our article on Mark Antony.

The Battle of Actium

The decisive confrontation came in 31 BCE at Actium on the western coast of Greece. Octavian’s fleet was commanded by Agrippa, while Antony and Cleopatra led the opposing naval force.

Octavian’s forces won the battle. Antony and Cleopatra escaped to Egypt, but their strategic position was effectively broken.

In 30 BCE Octavian invaded Egypt. Antony died by suicide, followed shortly afterward by Cleopatra. Egypt was brought under Roman control, and Octavian became the unrivaled leader of the Roman world.

Why didn’t Octavian simply become king?

Roman political culture had a deep hostility toward kingship. Caesar’s accumulation of extraordinary powers had contributed to his assassination, and Octavian had learned from that example.

Rather than openly declare monarchy, he presented himself as the restorer of peace and republican order. Traditional offices such as consulships, the Senate and popular assemblies continued to exist.

But the balance of power had fundamentally changed. Octavian controlled the armies and the most strategically important provinces, dominated patronage networks and held enormous prestige after ending the civil wars.

The First Settlement of 27 BCE

In January 27 BCE, Octavian formally returned certain powers and provinces to the Senate and Roman people. In response, the Senate granted him honors and the title Augustus, a name carrying religious and political prestige.

He also received control over a large group of provinces containing most of Rome’s standing legions. This gave Augustus command of the empire’s main military forces while allowing him to claim that normal republican government had been restored.

The year 27 BCE is therefore conventionally treated as the beginning of the Roman Empire.

The Second Settlement of 23 BCE

Augustus continued adjusting his constitutional position. In 23 BCE he gave up the annual consulship, which had become politically awkward, but retained other powers that allowed him to dominate government.

He received tribunicia potestas, or tribunician power, which gave him many of the privileges associated with the tribunes of the plebs. He also held superior provincial authority, allowing him to intervene in military provinces and command governors.

The result was a flexible political system rather than a single new office called “emperor.” Augustus accumulated powers that had republican precedents but combined them in a way no earlier politician had done permanently.

What was the Principate?

Historians often call Augustus’s political system the Principate. The word comes from princeps, meaning “first citizen” or “leading man.” Augustus preferred titles that suggested preeminence within the Republic rather than monarchy over it.

The Senate continued to debate and administer parts of the empire. Magistrates continued to be elected. Roman law and republican political language remained important.

At the same time, no senator could realistically challenge the man who controlled the armies, much of the provincial administration and the enormous prestige of the Augustan household.

Augustus and the Roman army

One of Augustus’s most important achievements was the creation of a more stable military system. The civil wars had produced huge armies personally loyal to competing generals. Augustus reduced the number of legions and created a more regular structure for service and retirement.

Veterans received settlements or financial rewards, and military service increasingly became a long-term profession. Augustus also created the Praetorian Guard, an elite force associated with protecting the ruler and Italy.

The army remained the ultimate foundation of imperial power. Later emperors would repeatedly discover that control of the legions could determine who ruled Rome. Our guide to daily life in the Roman army explores the soldiers behind that system.

Expansion under Augustus

Augustus did not stop Roman expansion. His armies consolidated control in Spain, pushed into Alpine and Balkan regions and extended Roman influence along the Rhine and Danube.

Not every campaign succeeded. The most famous disaster came in 9 CE, when three Roman legions commanded by Publius Quinctilius Varus were destroyed by a coalition led by Arminius in the Teutoburg Forest.

The defeat helped limit Roman ambitions east of the Rhine, although the frontier remained contested.

Peace and the image of a restored Rome

Augustan propaganda emphasized peace after decades of civil war. The phrase Pax Augusta or the broader idea of a Pax Romana became associated with stability under imperial rule.

The famous Ara Pacis, or Altar of Augustan Peace, celebrated this political message. Augustus presented his rule as a return to order, religion, prosperity and traditional values.

Peace did not mean the absence of war. Roman armies were campaigning throughout Augustus’s reign. The message was that Rome itself had escaped the cycle of internal civil conflict.

Building and reshaping the city

Augustus sponsored extensive building programs in Rome. Temples were restored, new public spaces were created and monuments connected the new regime with Roman history and religion.

Suetonius later attributed to Augustus the boast that he had found Rome a city of brick and left it a city of marble. The statement should not be read literally, but it captures the scale of Augustan transformation and later perceptions of his building program.

Important projects included the Forum of Augustus, the Temple of Mars Ultor and major improvements to roads, aqueducts and public administration.

Marriage laws and moral reform

Augustus also attempted to reshape Roman social behavior through legislation. Laws encouraged marriage and childbearing among citizens while penalizing certain forms of adultery and unmarried status among the elite.

These measures reflected Augustan claims that social stability required the restoration of traditional family values. Their effectiveness is debated, and Augustus’s own family repeatedly became entangled in the very moral controversies his legislation was intended to address.

Religion and the imperial image

Augustus linked his regime closely with Roman religion. He restored temples, revived priesthoods and emphasized traditional ritual.

After the death of Lepidus, Augustus became pontifex maximus in 12 BCE, making him Rome’s chief priest. His household and political authority became increasingly integrated with public religious life.

In the provinces, forms of ruler cult developed in which Augustus and members of his family could receive honors. In Rome itself, the political presentation remained more cautious during his lifetime.

The Res Gestae

Near the end of his life, Augustus prepared an account of his achievements known as the Res Gestae Divi Augusti, or “Deeds of the Divine Augustus.” Copies were displayed in different parts of the empire.

The text is an invaluable historical source but also a carefully constructed political document. Augustus emphasized service, generosity, military victories and constitutional legitimacy while minimizing the violence and coercion that had brought him to power.

The succession problem

Augustus built a political system centered on one ruler but never created a completely clear constitutional method for choosing the next one.

Several potential heirs died before him, including Marcellus, Agrippa, Gaius Caesar and Lucius Caesar. Augustus eventually adopted his stepson Tiberius.

When Augustus died in 14 CE at the age of seventy-five, Tiberius succeeded him with little immediate military opposition. That peaceful succession helped demonstrate that the new imperial system could survive its founder.

Was Augustus a dictator?

Augustus did not normally use the title dictator, and he carefully avoided some of the political symbolism associated with Julius Caesar’s final years.

Nevertheless, his regime was authoritarian in the sense that decisive military and political power rested in one individual. Republican institutions continued, but they operated within a system dominated by the princeps.

It is therefore more accurate to describe Augustus as the creator of a monarchy disguised in republican forms than to imagine that the old Republic simply continued unchanged.

Augustus and the beginning of the Roman Empire

Augustus’s greatest political achievement was not simply winning the civil wars. It was turning personal military supremacy into a durable system of government.

He reduced the instability that had destroyed the late Republic, reorganized the army, stabilized provincial administration and created a political language that made one-man rule more acceptable to Roman elites.

Later emperors changed the system, sometimes dramatically, but they continued to operate within a political world that Augustus had created.

Augustus timeline

• 63 BCE — Gaius Octavius is born.
• 44 BCE — Julius Caesar is assassinated; Octavius becomes his adopted heir.
• 43 BCE — Octavian, Antony and Lepidus form the Second Triumvirate.
• 42 BCE — Brutus and Cassius are defeated at Philippi.
• 36 BCE — Sextus Pompey is defeated; Lepidus loses political power.
• 31 BCE — Octavian defeats Antony and Cleopatra at Actium.
• 30 BCE — Egypt falls; Antony and Cleopatra die.
• 27 BCE — Octavian receives the title Augustus.
• 23 BCE — the Second Settlement reshapes Augustus’s constitutional powers.
• 12 BCE — Augustus becomes pontifex maximus.
• 9 CE — three Roman legions are destroyed in the Teutoburg Forest.
• 14 CE — Augustus dies; Tiberius succeeds him.

Augustus FAQ

Was Augustus the first Roman emperor?

Yes, Augustus is conventionally regarded as the first Roman emperor. Romans did not use “emperor” as a single constitutional office in the modern sense, but Augustus created the political system that historians identify as the beginning of imperial rule.

What was Augustus’s real name?

He was born Gaius Octavius. After being adopted in Julius Caesar’s will, he took Caesar’s name. Historians commonly call him Octavian for the period before 27 BCE, although he did not normally use that form himself. The Senate granted him the title Augustus in 27 BCE.

How was Augustus related to Julius Caesar?

Augustus was Caesar’s great-nephew through his mother’s family. Caesar adopted him posthumously in his will and named him principal heir.

How long did Augustus rule?

If his reign is dated from the settlement of 27 BCE to his death in 14 CE, Augustus ruled as Rome’s first emperor for about forty years.

Who succeeded Augustus?

His stepson and adopted son Tiberius succeeded him in 14 CE.

Sources and further reading

• Augustus, Res Gestae Divi Augusti.
• Suetonius, Life of Augustus.
• Cassius Dio, Roman History.
• Adrian Goldsworthy, Augustus: First Emperor of Rome.
• Werner Eck, The Age of Augustus.
• Encyclopaedia Britannica — Augustus
• The Metropolitan Museum of Art — The Age of Augustus