In 28 March AD 193 the emperor Pertinax was murdered after a reign of just eighty-seven days. His efforts to rule Rome with integrity and order had been generally welcomed. The Praetorian Guard, Rome’s spoilt, privileged and elite imperial bodyguard, was the most conspicuous exception. Pertinax had tried to instill meaningful discipline amongst the swaggering praetorians, who had become accustomed during the reign of Commodus to behaving as badly as they pleased, including hitting passers-by. To soften the impact of the new rules, Pertinax had promised the Guard 12,000 sestertii each, claiming he was matching what Marcus Aurelius and Lucius Verus had paid them on their accession in 160. Pertinax even sold off Commodus’ property to raise the cash, since the treasury had been reduced to its last million sestertii by his profligate expenditure and wild living. The praetorians, however, took exception to the idea they might return the favour by improving their behaviour. After all, they were aware that Marcus Aurelius and Lucius Verus had actually paid 20,000 sestertii to their predecessors and that Pertinax had possibly only ever paid half of what he had offered. The praetorians killed Pertinax but, terrified of the consequences of what they had done, they dashed back to their camp, the Castra Praetoria, and locked the gates.
Strangely, everything quietened down and the praetorians realized no one had come after them. Fully aware now that they were the ones who were really in charge, they posted a notice at the Castra Praetoria offering the Roman Empire for sale. Most of the senators were suitably disgusted, though the story as written by Dio may owe at least part of its inspiration to the events of the civil war year of 69 and the short rule of Otho. But one of them, a greedy and ambitious senator called Marcus Didius Julianus, drunk and egged on by his equally greedy and ambitious wife and daughter, Manlia Scantilla and Didia Clara, and two praetorian tribunes called Publius Florianus and Vectius Aper, raced round to the praetorian camp having spotted an opportunity. So did Titus Flavius Sulpicianus, who was the prefect of Rome as well as being Pertinax’s father-in-law. When Didius Julianus arrived he found that Sulpicianus was already there, busily securing his position and ensuring that Julianus was locked out. Only with the use of placards advertising his promises, and the transfer of a Sulpician supporter called Maurentius, was Julianus able to attract the praetorians’ attention.
What followed was rightly called a ‘disgraceful business’ by Dio, though the sheer theatricality of the description needs to be read with some caution. The praetorians capitalized on the fact that no one could hope to be emperor without their backing. Didius Julianus and Flavius Sulpicianus, each desperate for supreme power, started making rival cash offers to the Guard. The soldiers enthusiastically threw themselves into the auction, running across the camp between the candidates to tell each how much he would have to raise his bid by. Sulpicianus was about to win with an offer of 20,000 sestertii per praetorian when Julianus seized the day with a reckless counter bid of 25,000. Julianus added for good measure the warning that Sulpicianus might seek revenge for the death of Pertinax and also that he, Julianus, would restore all the freedoms the praetorians had enjoyed under Commodus. So delighted were the praetorians by the new offer they promptly declared Julianus to be the new emperor.
This event was so extraordinary, tawdry and demeaning that even now it seems barely credible that the Roman Empire could have stooped so low. Herodian described it as a decisive turning point, the moment when soldiers lost any respect for the emperors and which contributed to so much of the disorder that was to follow in the years to come. The Praetorian Guard had brazenly created an emperor purely on the promise of a huge cash handout, consummately and nakedly abusing their position and power. Julianus lasted even less time than Pertinax, having injudiciously offered far more money than he could afford. He was executed on the orders of the senate just sixty-six days after he was made emperor. By then Julianus already faced a rebellion in the east in the form of the Roman army in Illyricum under Septimius Severus, and failed to make any use of his praetorians; the civil war that convulsed the Roman Empire from 193 to 197 would be decided by Roman provincial forces, not the praetorians. Severus cashiered the Guard and recreated it with trusted legionaries from his own forces. Even that did not solve the problem. In the decades to come the Guard and its prefects played a decisive role in toppling and making one emperor after another.
How could it have come to this? The praetorians were the most privileged of all Roman soldiers. They were paid the most, served the least time, and enjoyed the best conditions. Their status exceeded that of all the other armed forces; but, in the two centuries or more since their formal foundation as a permanent institution by Augustus, circumstances had conspired to make them the supreme authority. In 193 it was a power they misused in so reprehensible a way it is hard to imagine how they could ever have recovered any of the prestige they had once enjoyed.
Edward Gibbon’s description of the Guard’s relationship with the emperor is unmatched for the clarity with which he identified the paradox inherent in the system:
Such formidable servants are always necessary, but often fatal to the throne of despotism. By thus introducing the Praetorian guards, as it were, into the palace and the senate, the emperors taught them to perceive their own strength, and the weakness of the civil government; to view the vices of their masters with familiar contempt, and to lay aside that reverential awe, which distance only, and mystery, can preserve towards an imaginary power. In the luxurious idleness of an opulent city, their pride was nourished by the sense of their irresistible weight; nor was it possible to conceal from them, that the person of the sovereign, the authority of the senate, the public treasure, and the seat of Empire, were all in their hands. To divert the Praetorian bands from these dangerous reflections, the firmest and best established princes were obliged to mix blandishments with commands, rewards with punishments, to flatter their pride, indulge their pleasures, connive at their irregularities, and to purchase their precarious faith by a liberal donative; which, since the elevation of Claudius, was exacted as a legal claim, on the accession of every new emperor.
The Guard’s ambitions, and those of its prefects, expanded to fill the voids left by inadequate or vulnerable rulers. Thus, Tiberius’ self-imposed exile to Capri made it possible for the praetorian prefect Sejanus to try and become emperor himself. The disastrous reign of Caligula in 37–41 led to his assassination and to the Guard appointing its own emperor in the form of Claudius. The loss of the Guard’s support played a key part in Nero giving up and committing suicide in 68. During the civil war of 68–9 the Guard played crucial roles in the fight between the rivals for the Empire. In the second century AD the succession of strong and effective rulers meant that from 98 until 180 the Guard rarely appears in ancient sources. The dereliction of the reign of Commodus (180–92) brought the Guard back to the fore once more and it was the behaviour of the praetorians that led to the murder of Pertinax and the brief and tawdry reign of Didius Julianus. In volatile and unsettled times the Guard acted as catalysts and opportunists, and their prefects as major players, for good or ill.
The events of 193 were therefore more or less inevitable, and the seeds had been sown the moment Augustus created the Guard more than two centuries earlier. The precarious balance was bound to be upset sooner or later, though as an institution the Guard survived this venal episode. Finally, in 312 Constantine I disbanded the Guard altogether after its ill-judged support for his rival Maxentius. The praetorians were individually dispersed to the frontier garrisons of the Empire. It was an ignominious end for an institution that had enjoyed a formal and permanent existence for 340 years and an ad hoc role before that as the personal bodyguard of Roman generals in the Republic.
This book does not focus on the details of the praetorians’ armour and equipment, a subject amply and excellently covered by Rankov (1994) and Cowan (2014). Instead, this book is a history of the Praetorian Guard from its beginnings right through to its final disbandment. The focus is on the Guard and its role, its formation, structure, conditions, deployment, leadership and its experiences within the narrative context of Roman imperial history. The evidence is complex and incomplete because the Praetorian Guard makes only erratic appearances in ancient sources. There is a great deal that is unknown, and which will probably remain so.
The term ‘Praetorian Guard’ is a modern one. The Romans knew the imperial bodyguard collectively as the cohortes praetoriae, ‘the praetorian cohorts’, and their fort as the Castra Praetoria, or Praetoriana, ‘the praetorian barracks’, or the Castra Praetorianorum, ‘barracks of the praetorians’, rather than conferring on either the Guard or its headquarters a singular title. This makes no difference to the fact that the Guard’s evolution into the highest-paid, most esteemed and most influential part of the Roman military machine has always made it a source of some fascination. Praetorians regarded themselves as a cut above the rest of the Roman military machine, as indeed they were. A praetorian centurion called Manlius Valerianus had his views memorialized on his tombstone at Aquileia. He had, he said, ‘commanded a century in a praetorian cohort, not a barbarian legion’.
The organization of the Guard, like so much else in the Roman Empire, was a good deal less precise and regimented than is often assumed today. Precedent, circumstances and expediency all played a part in the Guard’s history, with the result that there are numerous inconsistencies, such as the number and size of the cohorts, the pay, and even the duties praetorians performed, both individually and collectively. Nevertheless, the Guard emerges as an organization that played a vitally significant and continuous part in Roman history, and which helped define the image of the Roman state both then and now.
Recruitment into the Praetorian Guard at the start of a military career, or as a later promotion for a legionary, meant belonging to the most prestigious part of the most powerful organization in antiquity. It continued to give the men involved considerable standing in the communities where they lived in retirement as civilians. Then, as now, Roman soldiers typified a popular image of Roman power and society. The Roman state evolved with a tradition of compulsory military service for its citizens and with an ideology founded on a destiny of divinely backed victory and conquest. In Virgil’s epic poem the Aeneid, Jupiter set out the future for the Roman people. Aeneas, the mythical progenitor of the Julian line and ancestor of Augustus, would crush Italy’s fierce tribes and his descendant Romulus would found Rome, a city whose people would have no limits of time or space, and an empire that would never end. Rome’s wars did indeed expand Roman power, absorbing other states and communities, which would earn affiliated status instead of annihilation if their own soldiers were contributed to service on behalf of Rome. The men of the Roman senatorial elite customarily served as military officers as part of their career path, known as the cursus honorum. A huge proportion of male Roman citizens, of whatever class, had some military experience. They had either served as soldiers or as officers and many would have participated in military campaigns. From all this they acquired enormously important skills, not just in fighting but also in practical techniques such as building and administration.