The Praetorian Guard: From Elite Bodyguard to Power-Hungry Kingmakers

For three centuries, the praetorian guard served as the Roman emperors’ shield. But that shield could easily become a dagger in the emperors’ back.

Apr 27, 2021By Vedran Bileta, MA in Late Antique, Byzantine, and Early Modern History, BA in History
praetorian guard
Proclaiming Claudius Emperor, Sir Lawrence Alma-Tadema, 1867; with relief of a praetorian from Puteoli, 51-52 CE


One of the most elite Roman military units, known as the Praetorian Guard, started as a prestigious group of bodyguards loyal to the Roman generals and leaders of the Late Republic. After his victory in the bloody civil war, Emperor Augustus, now the sole ruler of the Roman Empire, officially established the praetorian guard. 


These soldiers were more than just bodyguards. The praetorians were the secret police, frontline soldiers, and occasionally even volunteer firemen in the city of Rome. Their proximity to the source of power and their monopoly on carrying arms in the imperial presence made the guards influential power brokers.


For three centuries, the praetorian guard not only protected emperors, they also conspired against them too, assassinating several. In the end, these ambitious soldiers went too far, and Emperor Constantine the Great permanently disbanded the Praetorians in 313 CE.


Origins Of The Praetorian Guard

praetorian guard
Relief depicting the Praetorian Guard (originally part of the Arch of Claudius), ca. 51-52 CE, Via Wikimedia Commons


The elite Roman imperial bodyguards, known as the praetorian guard, originated in the late Republic, when rival generals and leaders employed hundreds, sometimes thousands, of experienced soldiers as their bodyguards and companions. Their military prowess made them valuable assets on the battlefield, while their loyalty to their commanders, rather than to the Roman state, secured them an elite status. 


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In a camp, the bodyguard would stay close to their commander, whose tent was known as the praetorium (thus the unit’s name). The importance of the praetorian cohorts (“praetorian guard” is a modern term) increased during the bloody civil wars that extinguished the Republic. The victor, Julius Caesar’s grand-nephew Octavian, inherited not only the entire state but also all the soldiers – those who fought for and against him. Among his trophies were the praetorian cohorts of his rival.


With the Roman world finally at peace, Octavian, now known as the Emperor Augustus, discharged most of the troops, posting the remaining legionaries on the frontiers of the empire, rather than in Italy. But the control of the city of Rome remained critical for the emperor’s personal safety. Caesar’s untimely death was still fresh in his mind when Augustus formalized the praetorian cohorts into a permanent unit, loyal only to the emperor. Thus, the praetorian guard was born, becoming the ruler’s sword and shield. 


A Road To Power

statuette praetorian
Statuette believed to be a praetorian, 2nd century CE, Via the British Museum


As the Emperor’s personal guard, the praetorians were the only military unit allowed to carry arms in the capital. Initially, the praetorian cohorts were dispersed tactfully around Italy, but during the reign of Augustus’ successors, all the troops (around ten cohorts, a thousand men each) would be stationed at the edge of Rome, with three cohorts active in the city at any given time. The numbers, however, do not reflect the importance and prestige of the praetorians. For a start, all guardsmen enjoyed superior service conditions. They served less than other soldiers and earned a better wage (perhaps three times more than ordinary legionaries would).


The power delegated to the unit by the emperor was considerable, thus aristocrats and commoners alike feared the guardsmen. In one of his poems, Juvenal recalled the nail left in his foot by the sandal of a praetorian, who ran over him. While in Rome, praetorians did not wear armor, choosing white-colored togas instead. In disguise, they could operate efficiently as secret police, easily blending with the rest of the crowd.


To further emphasize their loyalty, the praetorian guard never obeyed senators, but took orders from an equestrian (an aristocrat of lesser rank) instead, who reported directly to the emperor. From 2 BCE, the unit was led by two praetorian prefects, while the emperor retained personal command. Despite Augustus’ best efforts, the guardsmen’s proximity to the source of power increased their influence and ambitions. Under Augustus’ successor, Tiberius, the powerful praetorian prefect, Lucius Aelius Sejanus, convinced the emperor to build the guard’s headquarters – Castra Praetoria – at the edge of the city. This veritable fortress not only gathered all praetorian cohorts in one place, but also became a striking symbol of their growing power and influence.


proclaiming claudius emperor sir lawrence alma tadema
Proclaiming Claudius Emperor, Sir Lawrence Alma-Tadema, 1867, Via Sotheby’s


When Tiberius retired to his Capri villa in the last decade of his reign, Sejanus became the emperor in all but name. However, his attempts to marry into the imperial family, and become Tiberius’ heir failed, and young Caligula became emperor instead. Aware of the danger posed by the praetorians, the new ruler paid their overdue bonuses at the start of his reign. But in 41 CE, Caligula’s fears were realized when he was murdered in a palace coup that involved the praetorians. 


The violent demise of Caligula set a dangerous precedent, when Caligula’s uncle and successor Claudius was put on the throne by the praetorian guard. For that, they were richly rewarded. Thus protectors had turned into kingmakers. 


The Praetorian Guard: The King-Slayers And Kingmakers

coins galba otho vitellius
Coins of Galba, Otho, and Vitellius, Via The British Museum, London


The praetorians, whose influence and power were by now apparent, were instrumental in toppling the Julio-Claudian dynasty, when they abandoned Nero in the favor of Galba in 68 CE. The infamous “Year of the Four Emperors” was an exercise in praetorian supremacy. Less than a year after he was installed with their support, the Emperor Galba was assassinated by the Praetorians. Avoiding Galba’s mistake, his successor Otho rewarded the guard. Otho’s reign, however, only lasted for three months. In a rare show of imperial strength, the new emperor Vitellius disbanded the praetorian guard, replacing it entirely with his men. But the clock could not be turned back. The men whom Vitellius cashiered went to the new contender, Vespasian, and supported his bid for the throne. This led to a rare moment in Roman history when two praetorian armies met on the battlefield. Vespasian ultimately prevailed, returning the expelled soldiers to their old positions.


Aware of the praetorian influence, Vespasian reduced the size of the guard and made his son Titus the praetorian prefect. Due to this change, the reign of the Flavian and Antonine dynasties passed without any significant interference from this powerful shadow army. During that period, the praetorians served on imperial frontiers — from Dacia to Mesopotamia. Praetorian soldiers, for example, appear in the reliefs on Trajan’s column, signifying the victorious results of their service. The praetorian guard was also expanded by a small amount (consisting of around 1000 horses), to include the elite cavalry wing, the equites singulars Augusti (“personal cavalry of the emperor”). The praetorians saw further service on the Danubian limes (the Danube border) under the emperors Lucius Verus and Marcus Aurelius.


When The Praetorians Auctioned The Empire

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Scene from Trajan’s Column, on which the emperor is accompanied by the praetorian prefect, and the soldiers of Praetorian Guard, Via


The assassination of Emperor Commodus in 192 CE brought the praetorian guard back to power. Commodus’ successor, Pertinax, tried to reform the guard and reduce their privileges — so he had to go. What followed was the most infamous display of praetorian power in Roman history. Aware of their advantageous position, power-hungry soldiers auctioned off the Roman Empire to the highest bidder. The winner of the bid was Didius Julianus, who promised 25,000 sesterces per guardsman – an exorbitant amount of money at the time. 


However, the Roman army stationed in the provinces, was unwilling to accept the new emperor, pushing the empire into a civil war. The eventual victor, Septimius Severus, tricked the praetorians to meet him outside the city in their full parade uniforms, but unarmed. Ordering them to strip naked, he dismissed all the guardsmen and forbade them to come within a hundred miles of Rome, on pain of death. Severus then formed a new praetorian guard that now consisted of his own loyal troops.


An Ignominious End

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Split in two rows Frieze of the Battle of the Milvian Bridge, 312-315 CE, Rome, via wikimedia


The reign of Septimius Severus saw the praetorian guard once again active on the frontier. However, this surge of activity did not diminish their role as kingmakers. Both Caracalla and Elagabalus were assassinated by the guard, while one of the praetorian prefects, Macrinus, was even able to reach the coveted throne. Albeit, he did not stay in power for long. In 235 CE, the praetorian guard played a minor role in the installment of Maximinus Thrax, the first of the soldier emperors of the third century. This chaotic century saw a shift of power away from Rome to the frontier, with both the emperor and the capital moving away from Italy. It was during this period that the army replaced praetorian guard as kingmakers. 


When Diocletian stabilized the empire in 284 CE, he further reduced the role of the praetorians. They were neither present in his palace in Nicomedia, nor at the courts of three other Tetrarchs (Diocletian’s co-rulers). 


coin of macrinus
Coin of Macrinus, The Praetorian Emperor, 217 CE, Via the British Museum


Once the center of power and influence, the Castra Praetoria in Rome now housed only a minor garrison. Not content with losing their preeminent role, Praetorians exploited Diocletian’s abdication in 305 CE, to promote their candidate Maxentius. When civil war broke out again in 312 CE between Maxentius and Constantine, the Praetorian Guard made a final gamble and lost. 


On October 28th, at the battle of the Milvian Bridge, Constantine’s seasoned troops massacred the praetorians and the rest of Maxentius’ forces. The defeated emperor drowned in the Tiber along with many of his guardsmen; a scene gloatingly depicted on the Arch of Constantine, and in many later artworks. 


Constantine was determined to eradicate the power of the praetorian guard. In 313 CE the unit was disbanded once and for all. The internal walls of their Roman fortress was dismantled, and all the gates leading into the city were walled up. The surviving guardsmen were sent to the far reaches of the empire. The office of the praetorian prefect survived, but he was never to lead the troops again. From now on, the prefect would be a senior civilian administrator of the empire. After three hundred years, the praetorian guard came to its ignominious end.


The Legacy Of The Praetorian Guard

silver coin emperor claudius
Silver coin of Emperor Claudius, showing the Castra Praetoria (symbol of praetorian power) on reverse, 43-44 CE, Via The British Museum, London


When Augustus formed the praetorian guard, he was not aware that he had created a force his successors could not control. True, the praetorian guard served their primary purpose well, protecting the emperor, and keeping the Senate and people in check. They also fought valiantly on the empire’s frontiers. However, their proximity to power, and their exclusive access to the emperor made the guardsmen, and in particular, their commanders, incredibly powerful and influential. The guardsmen had the power to make or break a reign, which they often did.


Since the guard was created to protect the emperor in Rome, their political fate remained closely tied with that of the city. During the first two centuries of imperial rule, Rome was the capital, and the Praetorian bastion solidified the guardsmen’s preeminent role in political and military affairs. When the capital and emperor moved from Rome to the frontier of the empire, the praetorians’ political power decreased. Instead, the third-century crisis brought the army into imperial politics. When the praetorian guard made their last gamble in a bid for power, it was the army that spelled their doom.


remains of praetorian fort
View of the Remains of the Praetorian Fort [the Poecile], Hadrian’s Villa, Tivoli, Giovanni Battista Piranesi, 1770, Metropolitan Museum of Art

Three hundred years of history are difficult to erase. Even today “praetorian” is a term that denotes an elite and ruthlessly loyal bodyguard, prepared to fight for his leader to the death. As in the Roman case, exclusive access to a leader makes a guard both valuable and dangerous. In addition, the term has transcended the boundary between reality and fiction; the most recent example being the scarlet-clad praetorian guard of the Supreme Leader Snoke, in Star Wars: The Last JediLong after Constantine disbanded the last of praetorians, the elite guardsmen of the Roman emperors are still alive in popular memory. 


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By Vedran BiletaMA in Late Antique, Byzantine, and Early Modern History, BA in HistoryVedran is a doctoral researcher, based in Budapest. His main interest is Ancient History, in particular the Late Roman period. When not spending time with the military elites of the Late Roman West, he is sharing his passion for history with those willing to listen. In his free time, Vedran is wargaming and discussing Star Trek.