Key takeaways
- Wikipedia dates the Republic from the overthrow of the monarchy, traditionally 509 BC, to 27 BC, when the Senate gave Octavian the title Augustus.
- Under the Republic, power was shared among annually elected magistrates, led by two consuls, and a Senate whose decrees were formally advice.
- The Republic was, in Wikipedia's words, an elective oligarchy, not a democracy, with powerful families largely monopolising senior offices.
- Augustus kept the old offices but combined powers with republican precedents into a new position, the principate, according to an EBSCO Research Starter.
- The end date is a convention: EBSCO's Roman Republic entry gives 29 BCE, and the settlement itself was adjusted again in 23 BCE.
- The Western Roman Empire collapsed in 476 AD; the Eastern Roman Empire lasted until the fall of Constantinople in 1453, Wikipedia notes.
The difference between the Roman Republic and the Roman Empire is a difference in who had the final word. In the Republic, authority was split among elected magistrates serving one-year terms, the Senate and citizen assemblies. In the Empire, one man — styled princeps, "first citizen" — held a bundle of powers that let him decide policy and control the army, while most of the old institutions carried on around him. The changeover is usually dated to 27 BC, but as this comparison shows, that date is a convention historians chose, not a moment Romans experienced as a revolution.
The two systems side by side
| Republic | Empire (Principate) | |
|---|---|---|
| Usual dates | 509 BC (traditional) to 27 BC | 27 BC onward |
| Head of government | Two consuls, elected for one year | The princeps (emperor): permanent single-person rule |
| Senate | Decrees were formally "advice" that magistrates usually followed | Legitimated the emperor; senators served as his legates |
| Army command | Consuls and praetors held imperium | Emperor held overriding proconsular imperium |
| Succession | Annual elections | In theory the Senate chose, mindful of the army |
The Republic column follows Wikipedia's article on the Roman Republic; the Empire column follows its Roman Empire article and the EBSCO Research Starter on the Augustan Settlement.
How the Republic spread power around
Wikipedia describes the Republic's constitution as an unwritten, constantly evolving set of principles passed down mainly through precedent. Each magistracy was held by at least two people at once (collegiality), and after a one-year term a magistrate had to wait ten years before holding the same office again. The two consuls were the highest ordinary magistrates; each could check his colleague. Only the centuriate assembly could declare war, and it elected consuls, praetors and censors. A dictator could be appointed for six months in a military emergency.
None of this made Rome a democracy. Wikipedia calls the system "an elective oligarchy, not a democracy", with a number of powerful families largely monopolising the senior magistracies — a useful contrast with Athenian democracy. The EBSCO Research Starter on the Republic adds that plebeians gradually gained the right to elect tribunes with a veto, and that Rome's main laws were written onto the Twelve Tables in 449 BCE.
How Augustus rebuilt the top without abolishing it
The Republic broke down in a series of civil wars. Julius Caesar was dictator for life when he was killed on 15 March 44 BC. His heir Octavian and Mark Antony defeated the assassins at Philippi in 42 BC, then turned on each other; Octavian won at Actium in 31 BC, as told from the other side in Cleopatra beyond the legend.
The EBSCO Research Starter on the Augustan Settlement sets out what happened next. On 13 January 27 BCE Octavian went before the Senate and renounced the extraordinary powers of the triumvirate. The Senate asked him to remain consul and govern Spain, Gaul and Syria for ten years, along with Egypt. Those provinces held about two-thirds of Rome's army. Three days later he received the name Augustus. On 1 July 23 BCE he resigned the consulship and was compensated with proconsular imperium that was "greater" than any governor's and with tribunician power, giving him the right to initiate or veto measures.
EBSCO's verdict is that every element of his position had "republican" antecedents, but cumulatively they were new: "It was the principate, and he was princeps." Another EBSCO entry, on Imperial Rome, calls it a type of constitutional monarchy in which Augustus, in practice, had the final word on all policy and kept control of the army.
Counting the years, and why the end date moves
A worked example shows how much the dates depend on your choice of endpoint. Since both dates are BC, subtraction works directly:
- 509 BC to 27 BC: 509 − 27 = 482 years of Republic.
- Using EBSCO's end date of 29 BCE: 509 − 29 = 480 years.
Crossing from BC to AD needs care, because there is no year zero. From 27 BC to the collapse of the Western Empire in AD 476 is 27 + 476 − 1 = 502 years (the method is set out in counting centuries correctly).
Each figure is only as firm as its endpoints. The 509 BC founding is "traditionally dated", and Wikipedia notes most modern scholarship treats the story of the expulsion of the last king as quasi-mythological. And the end can be placed at 31 BC (Actium), 29 BCE (the end date in EBSCO's Republic entry, and the year, according to its Augustan Settlement entry, that Octavian returned to Rome and celebrated a triumph) or 27 BC (the settlement). EBSCO's Republic entry states there is no consensus among scholars about what precipitated the end of the Republican system. Choosing where one period ends and the next begins is exactly the problem examined in periodisation in history.
What carried on into the imperial centuries
The Senate survived. Wikipedia notes that it could do little short of assassination or open rebellion to oppose an emperor, but retained symbolic centrality: it legitimated each emperor's rule, and in theory it chose the next one, mindful of acclamation by the army or the Praetorian Guard. Senators served as the emperor's generals, diplomats and administrators.
The emperor's powers also changed over time. EBSCO's Imperial Rome entry says the period from Augustus until 180 CE is usually called the Principate, and Wikipedia's Roman Empire article says the emperor's powers over time became less constitutional and more monarchical, culminating in the Dominate. The Western Roman Empire collapsed in 476 AD, while the Eastern Roman Empire lasted until the fall of Constantinople in 1453. Why the West ended is the subject of why Rome fell, and what was happening beyond Rome's borders in these centuries is in what was happening elsewhere when Rome ruled. Rome's earlier rise to Mediterranean power is covered in the Punic Wars.
Following the transition on a timeline
World History Timeline Sim, our own app, lays out major events chronologically and lets you browse by year, era, region, country or category, which makes it easy to see Actium, 27 BC and 23 BC as separate steps. Time Travel Mode lets you choose between options at a turning point, but its chains of consequences are simulations, not what happened. The app is free on Google Play with ads and optional in-app purchases, and the listing describes it as a companion to coursework, not a replacement for it, so the constitutional detail above still comes from the sources cited here. Related titles are in the education and brain training category.
Good to know
Frequently asked questions
What is the main difference between the Roman Republic and the Roman Empire?
When did the Roman Republic become the Roman Empire?
Was Julius Caesar a Roman emperor?
Did the Roman Senate still matter under the emperors?
Sources
- Roman Republic (opens in a new tab)Wikipedia — accessed
- Roman Empire (opens in a new tab)Wikipedia — accessed
- Augustan Settlement (Research Starter) (opens in a new tab)EBSCO — accessed
- Roman Republic (Research Starter) (opens in a new tab)EBSCO — accessed
- Imperial Rome (Research Starter) (opens in a new tab)EBSCO — accessed
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