Seizing and maintaining power in Rome: Roman emperors’ tough job

Over the five-century long history of the Empire and out of almost 60 imperial reigns regarded as legitimate, there was around thirty overthrows and 105 usurpations, among which 86 were more than mere identity frauds, and 18 led to recognition. This alone is well worth questioning: is there any explanation for it?

How did Roman emperors seize power and manage to keep it? One answer may seem obvious: by force. But it was not enough to secure lasting power. Even though pretenders or even recognized emperors came from the elites and had been approved by the Senate, like Galba in 68, or supported by quite a number of armies like Vitellius in 69, or had been a prestigious emperor’s son, like Domitian in 81 or Commode in 180,s, it never ensured their power would be strong enough to avoid being challenged, which meant being overthrown or to prevent failing to reach the status of princeps. Most often, overthrown emperors were deprecated as « tyrants ». As for those who had been unable to gain universal consent from the whole Empire, they were designated as « usurpers ».

  • Sella J., 2020, Tenir le loup par les oreilles. Prendre le pouvoir et le conserver dans la Rome impériale des premiers siècles, Ceyzérieu : Champvallon.

A consensus-bound power

The legitimacy of an emperor, hence the probability he had to maintain and transfer his power– whether by direct line of descent and/or by adoption –,depended on  consensus, that is to say consent by the very people who were bound to the emperor by duty of obedience. It actually meant universal consent by all the inhabitants of the Empire. The emperor had to be first and foremost accepted by the armies he commanded through his legates, next by the Senate where legates came from. And finally, by the people of Rome whose role was crucial and decisive in recognizing the emperor to ultimately delegate power. The prime importance of consensus was first highlighted by the works of some historians such as Pierre Grenade or Egon Flaig. In practice, consensus took on manifold expressions, from enthusiastic consent demonstrating forceful support or approval, to some more neutral expression limited to the absence of protest towards the emperor, or even in the most serious cases, to reaching a « consensus » by eliminating all protests.

After the news of Tiberius’ death in 37 after J.-C., his great-nephew and designated successor, Caligula, enjoyed well-documented unanimous demonstrations of joy. He was first acclaimed by the imperial guard, and then recognized by the senators coming to meet him outside Rome accompanied by a great many Town people. Then, sacrifices had taken place in his honour in provinces and army camps had sworn him in. But that was none of a guarantee for the future and  Caligula was very soon detested by a significant number of senators who, less than four years later, plotted to eliminate him.

The system was extremely fragile, since it was not constrained by a constitution which would have guaranteed stability. By law, the Empire remained a republic and the emperor was but the princeps, i.e. first among his peers from the Senate he belonged to and whose magistracies such as consulship he shared. If he managed to maintain this consensus, he could remain in power until he died. He could also proceed to adopt a successor, who most often was from his bloodline. He thus came to embody the republic, and his will therefore became source of law.

But if he happened to fail – due to military defeats or to the dissatisfaction aroused by his decisions or his behaviour– the consensus would then weaken and threaten to break up, hence requiring his elimination. An emperor who used fear to remain in power, without his « subjects’ » approval, became like a pretender who wanted to seize a power he was not entitled to. He was hence thought to hold the function illegitimately by claiming ownership of something that belonged to everyone and which could only be held through delegation.

Augustus, the founding example

Roman emperors lived under constant threat of being overthrown or assassinated– since no recently designated emperor could run the risk of leaving his predecessor alive. He could only hope to last if consensus was maintained, which was facilitated by the fear of further civil wars like those which had enabled the first emperor– Augustus (27 before J- C.- 14 after J.- C.) – to seize power. In order to remain stable, emperors had therefore to preserve and fuel the consensus. To that purpose, they were, consciously or not, led to abide by some rules.

It was rather thorny: Augustus had left a model, made up of a set of legal decisions, but also of his own example, established as the founding standard. He had purposely left an account of his achievements, known as Res Gestae. In this summary, he explained how he had been organised his power « for the sake of the State », how he had defeated all those who « were threatening this very same State» and how he had been bestowed « unanimous » consent from all the social groups without whom there would be no Res Publica government. Any of his successors could use it as a reference; even the passages in which Augustus stated he had refused some offices and honours he had been offered, such as dictatorship.

These « rules » for governing provided a kind of norm which left some room for innovation despite the limits they set. What had been authorized to an emperor could legitimately be done by any new trustworthy emperor provided it had been legitimated by use overtime. This implied some form of consensus. These innovations often appeared as misuse of power when they were not clearly in line with a legitimizing founding precedent which Romans called exemplum. That was how Augustus, despite the republican nature of the regime, had adopted his grand children as his successors. They died later, before they could reign, but the emperor nevertheless indicated in his Res Gestae that he would have liked them to succeed him. He thus opened up the possibility for others to move towards some form of hereditary power.

But beside these positive exempla, which were later on followed, adapted and almost officialised, there was another less visible, more hidden range of behaviours which could not be openly mentioned but which were as necessary to the preservation of power. Ancient Romans named these « government secrets » arcana imperii; these practices were a way to avoid losing power. They concerned a great range of situations, from matrimonial strategies to prosecuting for treason or straightforward elimination of a more talented and popular legate.

Arcana imperii

The behaviours brought to light through an accurate study of sources, although not always precisely described and acknowledged, may often be singled out by their stereotyped character.  The « monographic » study of one reign only does not allow to identify them clearly: historians will be tempted to see them as generated by psychological factors and demonstrate the inherent logic behind each imperial choice, they might sometimes even go as far as somehow rehabilitating the emperor through an empathic approach. Thus Nero, who can easily be characterized as « histrionic » or « megalomaniac », is described as « misunderstood » and « sullied ». The negative elements drawn from sources are then interpreted as « clichés » meant to discredit the emperor and merely resulting from the hostility of the authors i.e. senators avenging one of their peers’ death. It is therefore necessary to adopt a longer term approach so as to overcome the feeling of similar repeated facts sometimes given by sources and to be able to take into account reactions to the consensus variations.

It thus becomes clear that both senators and the emperor, constantly engaged with one another, spoke and acted in line with pre-established patterns whose meaning was clearly understandable by their fellow citizens. Of course, there is no denying  the tradition of senatorial hostility towards some emperors, but this tradition attests that facts, gestures and words were recorded to allow « categorising » such or such emperor.

If the authority in power chose to follow one type of government rather than another one using repeated mentions to one of his predecessors, it meant that he had chosen to be in line with an already identified tradition and style of reign. Similarly, if he broke ground by deciding to favour communication with the people or with the army rather than with the senators, he then became a negative exemplum for some members of the Senate. Finally, if he ended up murdering some threatening rivals because he had been unable to build a consensus strong enough to protect him from being overthrown, senators would accurately record the list of his victims as an indication of the tyrannical character of his power. That was the case of Caligula (37-41), Claude (41-54), Nero (54-68) or Domitian (81-96).

But that did not reveal any particularly narrow-mindedness from the Senate who could be said to be concerned only by what harmed its members most. It should rather be seen as a way to categorize models to be followed or to be avoided since, as senators, they were in a position to provide sound judgment. Because they were the indispensable collaborators of the imperial government, they were under constant threat, all the more so as they were the only ones likely to succeed the emperor who, at that time, could only be chosen among the members of the Senate.

Consensus fluctuations

A great many sources provide accurate information to reconstruct overtime, reign after reign, the course of consensus fluctuations: historical texts, laws, inscriptions, money coined by the government, architectural programs. The study of over two centuries of conquests and governments has been extremely fruitful and helped determine the mechanisms at work. It is not possible here to detail all aspects; the following are only a very small part of the whole range of possible issues: women’s influence in handing down and exercising power, adopting one’s successors, the influence of military campaigns, toleration of criticism, devotion to gods and the spreading of « divine signs » as a guarantee of power or heralding its failure …

Such approach could well be carried out over other periods. Our presidents never fail to refer to previous founding figures, be it Clemenceau by Manuel Valls, Poincare by Giscard d’Estaing, Blum by Mitterrand or de Gaulle by Chirac and Macron… But although their constant search for popularity in opinion polls may be compared to the tricky exercise of maintaining consensus, however, the death they risk is only symbolical.

Our societies also do need consensus, but they are regulated by constitutions and checks and balances expected to protect us from the most dangerous opponents ‘physical elimination and death conspiracy. Therefore, governing can no longer be associated to Tiberius’ frightful and exhausting image of holding a wolf by the ears without ever being able to let it go. And yet, even if the search for stability and prosperity remains constant in politics, it should be reminded that threats of a shift towards tyrannical power or a civil war breakout still remain: the latest news are full of examples, from poisoning opponents in Russia to kidnapping in Saudi Arabia or China or imprisonments in Turkey. In this respect, the study of the Roman imperial power provides us with some extremely enlightening food for thought.

  • Flaig E., 1992, Den Kaiser herausfordern. Die Usurpation im römischen Reich, Francfort/Main-New York : Campus Verlag.
  • Grenade P., 1961, Essai sur les origines du Principat, Paris : De Boccard.
  • Veyne P., 2005 L’Empire gréco-romain, Paris : Seuil.

Illustration by Adèle Huguet for Mondes Sociaux: all rights reserved Adèle Huguet. To discover more drawings,

Image credits in CC:  Flaticon Freepik, Smahsicons, utlimatearm, imaginationlol


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Jérôme Sella (2022, 10 janvier). Seizing and maintaining power in Rome: Roman emperors’ tough job. Mondes Sociaux. Consulté le 12 avril 2024, à l’adresse

Jérôme Sella

Jérôme Sella, Université Lille III, Halma UMR 8164 (

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