First there was the Roman Kingdom, then the Roman Republic and then the Roman Empire. But what was it that made it an empire the third time, rather than just going back to being a kingdom again?

Lucius Tarquinius Superbus was the last rex Romae (=king of Rome), Julius Caesar held the office of dictator perpetuo (=dictator for life) while Augustus was the first imperator (=emperor).

But isn't an emperor a king that is king over other—less powerful—kings? If so, who were these kings and kingdoms under Emperor Augustus?

Did the Romans themselves consider themselves as part of an empire rather than a kingdom? Or is this more of a modern distinction by historians, just to keep the time periods apart?

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    Thank you for your question; please consider revising it to be more in line with our community expectations. Like other stacks, we expect questions to provide evidence of prior research. That helps us to understand the question, and avoids our repeating work you've already done. Our help center, and other stacks provide additional resources to assist with revisions. Please revise your question to document your preliminary research. Commented Apr 16, 2022 at 17:00
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    An emperor does not necessarily rule over kings. You can be an emperor and rule directly over lords of various other titles/ranks aside from king. In fact technically there is a rank usually inserted between emperor and king: high king (which does usually rule directly over other kings). But such rankings are largely arbitrary.
    – TylerH
    Commented Apr 19, 2022 at 14:52
  • Might you be paying too much attention to places like Uganda or Ethiopia? Who doubts Idi Amin styled himself "Emperor" whose rulers seem to have been titled "Emperor" nore for their own aggransidement than It's true an emperor doesn't nec Commented May 25, 2022 at 17:01
  • Can you say whether (again) here means that the Question has been repeated, or that Rome was once and then became again a kingdom. I guess the OQ means not that there was a second Kingdom but simply that the Question is repeated… and how is that clear? Commented May 29, 2022 at 17:46
  • When you Ask who were these kings and kingdoms under Emperor Augustus, did they not, for instance, include Egypt, Germany Spain and large parts of central Europe? Commented May 29, 2022 at 17:55

3 Answers 3


This is mainly our modern way to look at it.

In contemporary sources, Octavian/Augustus was just a princeps among the senators of the res publica, who 'by declared intent' had 'restored the republic' and 'by accident' also held the title of imperator. Imperator in this sense meaning nothing more than 'commander' of the legions.

Being imperator itself might have come in handy in case of any opposition resorting to taking up arms against 'the man' and coercive powers much like our idealised image for an autocrat. But this option of violence was really for internal politics the less preferred method to rule — especially coming out of yet another civil war yet again — since the 'more peaceful' way lay in the powers of tribunicia potestas, forming the core of an emperor's legal means.

So in Augustus' publicised self-image and propaganda, he never was any type of monarch, so not an emperor, while in reality of course he established something just like that for which we have no better fitting modern word but: 'sole ruler'/mon-arch. In all practicality, Rome was a monarchy again, and functionally with Augustus they had a king again, but everyone was afraid to tell it like it is.

Augustus emphasised unbroken tradition and continuity, while in reality he told the senatorial ranks that they will own nothing on him in the political sphere and that they will be happy over this de facto disenfranchisement. And somewhat happy they were, with some grievances of course, since they stayed wealthy and otherwise powerful, with comparative social rank kept, but relative peace, law and order guaranteed by the new authority.

On the other hand, ancient Romans did not necessarily think of Augustus as "the first imperator" either. Roman historian Cassius Dio (died 235) for example "hailed Julius Caesar as first imperator" (Cf: — Chapter 4: Konstantin V. Markov: "Cassius Dio’s Periodization of Roman History and His Methodological Agendas", in: "Cassius Dio the Historian" doi. Also compare the relevant passages in Dio's books 44 & 53, the latter showing neatly how most of the most important 'the republic''s offices & titles, powers & rights coalesced into one new office of eventually 'emperor' under Caesar and Augustus. Republican separation of power simply ceased to be in practicality.)

The Roman political system came to define itself during the republican years as 'anti-monarchical'. So much so, that when Julius Caesar became 'dictator for life' one of the motivations for his killers was the fear that he might strive to become a rex (king). This is one of the reasons that Octavian/Augustus and his first successors avoided this vocabulary as much as possible. Rome was still a republic, 'on paper'.

So, what we primarily see are multiple shifts in meaning for certain words. Rome never again became a kingdom, as there never came any king after the 'smallish state'-time before 'the Republic'. The emperors were also called 'caesars', 'princeps', etc.

'The Romans' never saw themselves as part of 'the empire', as that English word took on its meaning much later:

empire (n.) mid-14c., "territory subject to an emperor's rule;" in general "realm, dominion;" late 14c. as "authority of an emperor, supreme power in governing; imperial power," in Middle English generally of the Roman Empire. From Old French empire "rule, authority, kingdom, imperial rule" (11c.), from Latin imperium "a rule, a command; authority, control, power; supreme power, sole dominion; military authority; a dominion, realm," from imperare "to command," from assimilated form of in- "in" (from PIE root *en "in") + parare "to order, prepare" (from PIE root *pere- (1) "to produce, procure").

Whereas we see the rather succinctly put:

The Latin word imperium, referring to a magistrate's power to command, gradually assumed the meaning "The territory in which a magistrate can effectively enforce his commands", while the term "imperator" was originally an honorific meaning "commander". The title was given to generals who were victorious in battle. Thus, an "empire" may include regions that are not legally within the territory of a state, but are under either direct or indirect control of that state, such as a colony, client state, or protectorate. Although historians use the terms "Republican Period" and "Imperial Period" to identify the periods of Roman history before and after absolute power was assumed by Augustus, the Romans themselves continued to refer to their government as a republic, and during the Republican Period, the territories controlled by the republic were referred to as "Imperium Romanum". The emperor's actual legal power derived from holding the office of "consul", but he was traditionally honored with the titles of imperator (commander) and princeps (first man or, chief). Later, these terms came to have legal significance in their own right; an army calling their general "imperator" was a direct challenge to the authority of the current emperor.

Wikipedia: Empire, Classical_period

The most important shift is of course then for 'republic' itself: from res publica ('the common good'/'the (Roman) state'), since 'the Roman Republic' was not a republic, but just that: 'the republic':

republic (n.) "state in which supreme or executive power rests in the people via representatives chosen by citizens entitled to vote," c. 1600, from French république (15c.), from Latin respublica (ablative republica) "the common weal, a commonwealth, state, republic," literally res publica "public interest, the state," from res "affair, matter, thing" (see re) + publica, fem. of publicus "public" (see public (adj.)).

After 'the republican times' of course, the Roman 'state' was much larger than the formerly tiny kingdom and almost fitting to the modern definition of empire. It was different enough from the almost mythical 'kingdom of Rome', or any other kingdom really, obviously, no longer 'a' republic as we would recognise it either from our modern definitions or from comparison with the reality of the ancient construct, but something new.

For this understanding of 'an empire', we do not need to resort to 'kings under the king Augustus'. There of course would be people like the Herodian kings, under the Roman emperor (up to 92 AD), or others like in Armenia, but this is not necessary for 'an empire' to be one. For Rome itself, it might be practically called 'an empire' since bang in the middle of republican times, in my view at the latest right after 'unifying' the Italian peninsula, that is conquering Magna Graeca, and getting into trouble with Carthage.

That there would be a king of kings is a middle-eastern concept superfluous to describe mediterranean situations.

How did this remarkable man convince a majority of his benevolence and rectitude? How did he prove to them that he was not ‘king’ or ‘dictator’, but princeps, the leading citizen amongst equals—and this despite the fact that there were few who did not know how much real power he held? How did he succeed in persuading members of the senate and others to subordinate their wishes and ambitions to his will? What was the reason for the enthusiasm which led people to eulogise Augustus as ‘the restorer of the Republic’, and sometimes even to want to worship him as a god upon earth? How was it that, after his death, the deified Augustus seemed to live on to become not only an object of general admiration, but also one of emulation for many of his successors?

— David Shotter: "Augustus Caesar", Routledge: London, New York, 1991.

Comparing the English word 'empire' to the Latin Imperium Romanum coming to roughly mean 'the Roman Realm' by the time of Cicero, Pompey, Caesar:

If the imperium by which the members of the senatorial elite in Rome waged war on behalf of the state was a power, almost a substance, affirmed by the gods to particular individuals, the question remains as to how this affected the way in which warfare itself was seen, and also that ultimate outcome of warfare, the Roman control of the world, the imperium Romanum. In part, as suggested above, this is a question of linguistic usage: why did the expression imperium Romanum come to be used to express 'empire' rather than the power of a magistrate or pro-magistrate?

It is worth noticing at this point that this second meaning is different in two important respects from what has been discussed hitherto: it is about only one of the two spheres of application of the imperium of a magistrate, militiae but not domi; and it is not individual but corporate, relating to the power/empire of the populus Romanus rather than of any particular Roman.

It was, of course, always true that in some sense the power of the magistrate was that of the populus Romanus, in that wherever the imperium holder was, there the power of the populus Romanus was to be found. In the case of the imperium Romanum, in the sense of 'empire', however, the identification with the respublica is much stronger and the central importance of the imperium holder seems to have disappeared almost entirely.

This second point can be seen clearly even in those rare passages in the literature of the late republic and early empire in which imperium populi Romani, used in a wider sense than simply 'power of the magistrate', includes the notion of domi as well as that of militiae. For instance, Livy can make the tribune C. Canuleius ask, when contending with patrician opponents about his bill on conubium, 'denique utrum tandem populi Romani an vestrum summum imperium est? regibus exactis utrum vobis dominatio an omnibus aequa libertas parta est?' In this context, the form of imperium, in so far as it is relevant to the argument Livy is presenting, is both domi and militiae, since Canuleius suggests the consul will call up the army to threaten the plebs and their tribune. Yet even in this deliberately heightened and paradoxical passage (Mommsen described it as 'politische Speculation, nicht technische Rede'),the question at issue is precisely who it was that held the imperium, whether it was to the magistrates or to the people that the army owed its allegiance. […]

The gens Iulia and the triumphatores of the republic formed a continuum, which had its origins in the founder of the Julii and in the king, son of the god Mars, who had first held imperium and (according to the Augustan Fasti Triumphales) first celebrated a triumph on the first day of the first year of the foundation of the city. In the midst of the forum stood a triumphal chariot, honouring Augustus himself, voted, as he tells us in the final section of the Res Gestae, by the senate, and below which was placed the tablet recording the award to him of the title Pater Patriae.

This was to be the setting in which the senate would consider the award of triumphs, from here those who went with imperium to the provinces would set forth, and it was here that, if they were successful, they would come to be rewarded with ornamenta triumphalia.

In such a context the commanders of the forces of the Roman people could not fail to realize that it was imperium militiae, passed down from the kings through the great individuals of the republic, that had made the imperium Romanum; nor indeed amid such surroundings did it need to be stated explicitly that it was from the exercise of imperium throughout the known world that monarchy had made its return to Rome.

— J. S. Richardson: "Imperium Romanum: Empire and the Language of Power", The Journal of Roman Studies, Vol. 81 (1991), pp. 1-9. jstor

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    Great answer. It might be worth noting the Renaissance idea that an empire was necessarily an autarky, whereas a kingdom might have an overlord. E.g., Henry VIII's proclamation "that this realm of England is an Empire" when he rejected Papal authority in England.
    – Mark Olson
    Commented Apr 16, 2022 at 20:13
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    I agree, great answer. I would slightly alter this: I would hold that Roman was essentially an empire during the Republican period, e.g. after the Punic wars, being dominant in their region and having vast power (including drafting troops) from client states.
    – sharur
    Commented Apr 17, 2022 at 1:46
  • @sharur Thx. Point well made, although I'd pinpoint my opinion over 'what/when is an empire' even a bit earlier, based on the very same definition you used. I included a bit about that, and expressly endorse your view on that as well. Commented Apr 17, 2022 at 2:08
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    I remember reading (long ago) that Caesar, after returning victorious from some campaign, was greeted with some scattered shouts of "Rex" from the plebeians he rode through. And while these cheers were positive (hailing to glorious olden days), it worried him a lot because of the negative connotations of that title.
    – Oliphaunt
    Commented Apr 17, 2022 at 22:06
  • "In all practicality, Rome was a monarchy again, and functionally with Augustus they had a king again, but everyone was afraid to tell it like it is." This is heavily incorrect. Augustus kept nearlly all Republican institutions and office positions. He himself ruled using the Republican titles, accumulating many office positions by himself. This is not how a monarchy works, not in practice, not in theory. Furthermore, nobody was afraid to tell like it was, this is also heavily incorrect. The new Octavian's power was very public, discussed, rumored, and definitely, spoken like it was.
    – James
    Commented Apr 20, 2022 at 7:58

The English word “Empire” comes directly from Latin “Imperium,” was originally used as a name for the Roman Empire, and has, over time, been extended to other polities that resemble the Roman Empire.

If we look up the definitions in a modern dictionary, such as Merriam-Webster, the primary ones we see are:

  • a major political unit having a territory of great extent or a number of territories or peoples under a single sovereign authority

especially : one having an emperor as chief of state

  • something resembling a political empire

especially : an extensive territory or enterprise under single domination or control

Since the Roman Empire was a large, multi-ethnic state ruled by a dictator with the title of Emperor, the more of those traits something has, the more the word Empire fits it in modern English. (Hence, when Voltaire said in French, “neither Holy, Roman nor an Empire,” contemporaries understood the joke that the Holy Roman Empire had lost its territories outside Germany and its Emperor had minimal authority over his nominal vassals.) But, historically, people started out calling Rome an “imperium” first, and only later created a category called “imperial” or “empires” for things that are like it.


If the Roman Emperors had a single title, it would be more likely a phrase - Imperator Caesar Augustus - instead of a single word like Princeps or Imperator.

The first emperor, Augustus, was more or less a dictator in the modern sense, having gained total control in a series of civil wars. But to please the senators, he disguised his power - not that they were fooled, but they appreciated his politness in not flaunting it in their faces and thus forcing them to revolt against that humiliation. So Augustus accumulated a number of more or less normal republican titles, powers, and offices to give him the legal right to give the orders that he would have given anyway.

During the period of the Principate the emperors were more or less absolute rulers and more or less monarchs, but claimed to be merely very, very influential senators with a number of republican positions though they claimed that less and less as time went on. During the period of the Dominate, beginning at least as early as the reign of Diocletian (284-305) the emperors claimed absolue and monarchial power.

All of the emperors beginning with Augustus tried to establish hereditary imperial dynasties. During the Crises of the Third Century some of those dynasties lasted only two reighs and only three or four years, and in general Roman imperial dynasties were short lived.

So much so that I have read that Emperor Justinian II (reigned 685-695 & 705-711) made a big deal about being the first fifth generation of Emperor from father to son in imperial history. And if his son and co emperor Tiberius IV was killed after him he would have been the first sixth gentration emperor ever.

And the next fifth generation emperor was John V Palaiologos in 1341, and the next 6th generation emperors were Andronicos IV in 1976 and Manuel II in 1391. And the first three 7th generations Emperors would be John VII, John VIII, and Constantine XI from 1390 to 1453. And the 8th generation emperors would have been Andronikos V (who died before his father and never became sole ruler) and Andreas Palaiologos, titular emperor in exile from 1465-1502.

The Magas Komenos dynasty at Trebizond had 9th gneration emperors with John IV 1428-1490 and David 146-1461, and a 10th generation empror Alexios V who reigned for a few days in 1460. But the succession in Trebizond didn't pass from father to son uninterrupted but often passed to brothers, uncles, nephews, etc.

And in the holy Roman Empire, if that counts as a branch of the Roman empire, not even the Habsburgs achieved more than four generations of father to son succession. Although Joseph I (r. 1705-1711) was descended in the male line from nine kings of the Romans, elected emperors of the Romans, and full emperors of the Romans. In total there were 16 kings of the Romans, elected emperors of the Romans, and full Emperors of the Romans of the Habsburg dynasty plus a disputed king of the Romans, and 4 more elected emperors of the Romans in the dynasty of Habsburg-Lorraine.

And many Roman Emperors did have client, tibutary, or vassal kings, but some did not. And there have been many rulers who had subordinate kings but who were not emperors.

In my opinion, the only emperors in European Culture were Roman emperors of varius types, including "Byzantine" and Holy Roman Emperors. Other European monarchs who claimed to be emperors but not Roman Emperors were not emperors in muy opinion. I think that they should be called "imferators" instead of imperators, and their realms should be called "inferiums" instead of imperiums.

And the groups of colonial possessions many European countries acquired in ecent centuries are often called "empires" but I don't think that they should be. Since they usually included possessiosn across seas and oceans they could be called Thalassocracies, "ocean realms".


And lots of states in non europrean cultures have been called "empires". And I believe that only some branch, incarnation, or avator of the Roman Empire should be called an empire. But some non Euroepan states - though they were not Roman Empires - were similar enough to the Roman Empire to be called empire equilvalents and for their monarchs to be called emperor equivalents.

So in my opinion a minority of the non European states that are sometimes loosely called empires can be conisdered to be empire equivalents. And no doubt opnions would differ greatly about which ones to consider to be empie equivalents.

States which many persons might consider good candidates for being considered empire equivalents included the Inca Empire, the Iranian Empire under the Achaemenid, Arsacid, and Sassanian Dynasties, The Islamic Caliphate, The Ottoman State, the Mughal Empire, the Great Khaganate of the Mongols, and The realms of the more powerful Chinese Dynasties, for example.

And oF course the rulers of those states didn'tcall themselves emperors, but used other titles. And there may have been other rulers who used the same titles as them but were much less like emperor equivalents than they were.

For example, the rulers of the Iranian Empire in the Achaemenid Dynasty used the title of "The Great king, the King of KIngs, the King of Lands and Peoples, the King of the World (or the Universe)", and in the Sassanian Dynasty used the title of "King of Kings of Iran and of Non Iran". In those cases the title of king of kings can be considered to be an emperor equivalent title.

But many other rulers claimed to be kings of kings without being qualified as emperor equivalents. For example, there are several cases of kings of kings being subordinate to Roman Emperors andothers were subordinate to various emperor equivalents. So assuming that king of kings is always equivalent to emperor is a unwise assumption.

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    I guess there is a typo in the next 6th generation emperors were Andronicos IV in 1976 and Manuel II in 1391.
    – apaderno
    Commented Apr 18, 2022 at 9:39
  • Yes, the full title includes Imperator, Caesar, and Augustus like in Imperator Caesar Divi Filius Augustus, the official title of Gaius Julius Caesar Octavianus.
    – apaderno
    Commented Apr 18, 2022 at 11:09
  • This answer starts strong, rambles a bit in the middle about how long this or that dynasty was, and then drifts into an odd attempt to redefine the English word "emperor", without really explaining why. Is your central point simply that the title "imperator" isn't equivalent to the modern English title "emperor"?
    – IMSoP
    Commented Apr 19, 2022 at 20:05

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