List of Genealogical Tables

The aim of these charts is to bring out the relationships of the emperors to each other, for one of the main contentions of this study is that heredity was a mainspring of the succession process.

Certain conventions are used: names in capitals are emperors; dotted lines indicate adoptions.

IThe Julio-Claudian Dynasty (simplified)

IIAugustus’ Search for a Successor

IIIM. Agrippa as an Imperial Ancestor

IVAugustus’ Design for the Succession, AD 6

VThe Succession to Tiberius

VIThe Candidates after Gaius

VIIThe Flavians

VIIIThe Antonine ‘Dynasty’: Actual (genetic) Relationships

IXThe Antonine ‘Dynasty’: the Official (adoptive) Version

XPertinax’ Competitors

XIThe Severan Dynasty

XIIThe Gordian Dynasty

XIIIThe Philippian Dynasty

XIVThe Messian dynasty

XVThe Licinian Dynasty

XVIThe Tetrarchs

XVIIThe Dynasty of Constantine

XVIIIDynastic Connections between the Houses of Constantine and Valentinian

XIXThe Valentinian/Theodosian Dynasty

XXConnections of Anthemius

XXIConnections of Avitus and Petronius Maximus

XXIIThe Dynasty of Leo

List of Tables (Emperors)

Table IUnsuccessful Emperors, 220–238

Table IIUnsuccessful Emperors, 238–284

Table IIIUnsuccessful Emperors, 285–330

Table IVUnsuccessful Emperors, 350–395

Table VUnsuccessful Emperors, 379–425

Table VIEmperors, Dates and Origins


This book is an investigation of the processes by which a man could become a Roman emperor. I considered, briefly, entitling the book ‘How to become an Emperor’, before, if a little reluctantly, concluding that it would be as off-putting as it is enticing, but it would certainly have shown well enough the gist of my intention.

There are about eighty men who have been ‘recognized’ as emperors. The number is only approximate because there has never been a clear definition of the process of recognition that would separate the ‘legitimate’ emperors from the ‘usurpers’. It is, in fact, a matter of personal opinion in the marginal cases, though it is also the case that most historians believe that they can discern those who have achieved some sort of acceptance. Yet there has been, so far as I can find, no survey or study of what happened so that one particular man could be entered on the list, whereas others were not.1 There are those who are generally dismissed as ‘usurpers’ or ‘pretenders’ and are usually listed separately, or perhaps are distinguished by being named in italics, or they might be omitted altogether. Yet many of the most notable emperors, including even Augustus, the four emperors of AD 68–69, Nerva, Septimius Severus, many of the third-century emperors, Constantine, perhaps Theodosius, and some of the fifth-century men were originally usurpers in that they rebelled against the ruling emperor and then forced themselves into power.

Classifying men as usurpers is a subjective judgement, or perhaps one made with the use of hindsight: no one really counts Augustus or Constantine as usurpers, yet they were both men who fought their way to the imperial office from the position of outsiders, using force to impose themselves. Their acceptance is presumably because they were clearly very successful emperors, and those reigns were long in years. In that case, why classify anyone as a ‘usurper’? Some of the men classed as usurpers ruled huge parts of the Empire for several years – Pescennius Niger, Clodius Albinus, Magnentius, Magnus Maximus – before succumbing to attacks by an ‘official’ or ‘legitimate’ ruler. Also how does one classify the rulers of the ‘Gallic Empire’ of the third century? These ‘usurpers’ were clearly accepted by their subjects as legitimate rulers, and even in some cases, briefly, also by their own ‘official’ competitors, and the Gallic regime lasted for a decade and a half, longer than most emperors. Then there is a curious set of emperors in the West in the third quarter of the fifth century, imposed often by one outsider ‘barbarian’ or another; why are some accepted as emperors whereas others are not?

These are not really questions that can be answered other than subjectively, so it seems to me best to ignore them, and so to ignore the supposed distinction between usurpers and legitimate rulers. (Latin, in fact, does not have a word for ‘usurper’, which suggests that it is a modern European notion, based on the practice of a legitimizing coronation, which is imposed on the ancient situation.) So I shall avoid as much as possible the concept of usurper, and consider any man who achieved any sort of acceptance as an emperor to be an emperor, though we will also need to distinguish those who were quickly eliminated from those who did them down; perhaps some sort of minimum time in power, and a clear geographical range of authority might work, but that would only open up another area of fruitless and endless controversy. In fact, of course, the list of usurpers would be much the same as a list of failures, but it is not really a modern historian’s task to award such labels and it will be most straightforward to regard all of them as emperors, however long they ruled and whatever the geographical extent of their power. This will, in turn, allow an unbiased consideration of their careers without labelling them in a derogatory way from the start.

The first essential in considering the success or failure of an emperor in establishing his rule is to discover what actually took place at the time he was made emperor, that is, at his accession. The actual process of proclamation and acceptance is one of the keys to understanding; another is to locate the groups of Roman subjects who do the proclaiming and accepting. In many cases these groups are revealed to be relatively small in number and restricted in composition, and were formed overwhelmingly of the powerful and wealthy; in only a very few accessions do any of the ordinary people of the Empire have any influence. The choice of emperor, therefore, is one that was made by a relatively small set of wealthy and powerful men: the Senate, the army, the provincial governors, and sometimes the bureaucracy do have a say, however, and when there are disputes between them over an accession one can see fairly clearly the accession process in action. It is the support of some or all of these sets of people that ensured a man reached and stayed on the imperial throne.

As with anything else in the Roman imperial system, it is necessary first of all to consider the motives and methods and practices of the first emperor, Augustus. His claim to authority was based on his inheritance from his uncle, Julius Caesar, and it was his wish to be the father of a dynasty. At the same time he co-opted the Senate into accepting his rule, while his achievement of power is based essentially on his control of a successful army. His various expedients and improvisations in pursuit of his domestic policies set the pattern for the various accession processes of later emperors, a pattern of methods which, in some cases, was still visibly active in the fifth century. That is, the long-time essential keys to becoming emperor were the army, the Senate, and dynastic inheritance.

Beyond the seizure of power by Augustus, whose long reign convinced most in the Roman Empire that an imperial system was here to stay, his constitutional contortions did not need to be repeated. As a result there was also, for the next five centuries, an emperor already in office when the next one was contemplating his own accession. So the preferences of the ruling emperor had to be considered, and the accession of an emperor was very often also a succession; one of the major influences on the choice of a new emperor was always the wishes of his predecessor. This was not, however, always paramount, and again it is in cases where there were disputes that a brighter light is shone on the process. Despite the disputes and the obvious power of the army and the Senate, it is clear that heredity was always a major influence on the choices made; yet this was a process that could produce emperors of the very worst sort.

This has helped to determine the organization of this book. Every now and again the choice of emperor became the occasion for a major imperial crisis. A change of ruler is always a problem; even in law-abiding Western democracies, the police, and even the armed forces, are on alert at an election or an inauguration or a coronation. In Rome, where no clearly accepted succession process existed, the occasion was always fraught with danger. At times it was more than a problem, but was a crisis that might develop into anything from a quiet and acceptable coup d’état to a lengthy civil war. These occasions are distinguished here as ‘crises’, in each of which a new pattern of the selection process was established and then became the norm for the next historical period. Each ‘crisis’ is, therefore, followed by a consideration of its ‘consequences’.

The Empire itself was regarded by many as an illegitimate political entity, at least during the first century or so of its existence. Apart from incorrigible rebels like the Jews, or other unwillingly conquered or conscripted subjects, a category that could be applied to almost everyone outside Italy, many of the Roman nobility were convinced that the imperial regime was one that had no right to exist. It was the view of this group that the emperor had seized the power that rightly belonged to ‘the Senate and People of Rome’. These were, above all, the senators, whose power was leashed and diminished by the existence of an emperor, and they were eventually reconciled by time, by suppression, by co-optation, by weary recognition, and by the sheer continuance of the imperial regime. How far Augustus’ sleight-of-hand ‘restoration of the Republic’ convinced them is not clear, but was probably very limited. (There were also senators who did not object so much to the imperial regime as to the fact that they themselves were not the emperor; a source of some instability in all reigns. No imperial reign was free of such instability, and all because of Augustus and his methods.) Even so, the influence and anti-imperial argument by the dissidents remained everlasting and sapped the right of any man to be regarded as the ruler of the world. Not even the eventual support of subservient Christianity, co-opted into power by its sworn enemy, could help in this.

This perceived imperial illegitimacy is one of the explanations for the continuing savagery and violence of the succession process. Many emperors swept the board clean of their possible successors, especially those who were members of their own families, since any obvious successor was thereby a threat. Once hoisted on the imperial petard, many emperors had to wield the sword to stay aloft, and many did not last very long. This, of course, was ironic: emperors always looked to found a dynasty, yet their murderousness operated to deny their families the chance to survive and succeed. This again is a pattern initiated by the first emperors. The majority of emperors died violently: seven out of the first twelve.

This is a study of historical process, in which I hope to discern any changes over time – that is what history is, after all – but also to note when change did not take place. It follows that the chronological approach is the only one that makes sense. I end at the expiry of the last emperor of the West, with a few remarks on the system as it continued in the Eastern Empire. For it is the absence of an emperor – puppet or ruler – which is correctly taken to mark the end of the Empire itself, in 476 in the West, and 1453 (a date that stretches the definition of the ‘Roman Empire’ to breaking-point) in the East. So one of the results of this study will be to illuminate another aspect of the ‘fall’ of the Empire. At least the succeeding ‘Roman’ Empires – Russian Tsardom, the Ottoman regime of the ‘Sultan-i-Rum’ (Sultanate of Rum) – do not need to be included, though their histories have many parallels with that of the original.



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