Rome’s first emperor Caesar Augustus (r.31 BCE-14 CE) created a personal bodyguard called the cohors praetoria or Praetorian Guard in 27 BCE consisting of nine double-strength cohorts to protect himself and ensure domestic tranquility after a century of Roman civil wars. The guardsmen were organized, trained, and armed like the regular legionaries, but were hand-picked veterans initially of Italian origin who were paid much more than normal Roman soldiers and received benefits after only sixteen years of service (instead of the normal twenty years). Moreover, the Praetorian Guard was the only fighting force stationed in Italy. Augustus originally organized the guard so that only three cohorts would be in Rome, the other six were to police the hinterland, with rotation back to Rome each spring and fall. But after Augustus' death in 14 CE, this rotation fell apart and the majority of the guard stayed at home where they often participated in the selection of future emperors. In fact, four of Rome's emperors were “raised to the purple” (so named due to the rarity and expense of the eastern Mediterranean purple dye associated with imperial trappings) from the ranks of the Praetorian Guard, giving them the often-infamous distinction of “emperor-makers.”

Right: Praetorian Guardsman wearing cohors togata from the pedestal of a triumphal arch for the Emperor Trajan, early second century CE. Pergamon Museum, Berlin. Source: Wikimedia. 

The original cohors praetoria were elite units who functioned as bodyguards for Roman generals, a practice dating back to the second century BCE, with the famous victor of the Third Punic War (149-146 BCE), Scipio Africanus (236-183 BCE) being among the first to use them. Augustus understood the importance of an elite bodyguard to protect him and his court, having lived through the assassination of his adopted father Julius Caesar (100-44 BCE) in 44 BCE, and the use of Roman legions in Civil Wars throughout his entire lifetime, including in his own wars against Mark Antony (83-30 BCE) and his consort Cleopatra VII, the last Hellenistic queen of Egypt (r.51-30 BCE). So, to secure his early reign after Mark Antony and Cleopatra’s defeat at the Battle of Actium in 31, Augustine resurrected the cohors praetoria, this time as an imperial bodyguard stationed near the ‘Eternal City” while consciously creating a grand strategy where the remainder of the Roman legions were placed on the Roman frontiers to keep them closer to the enemy and farther away from Italian politics. Even Augustus understood the danger of having his bodyguard billeted within the walls of the capital, requiring three of the cohorts to stay in close proximity to Rome in local towns, while the other six policed the peninsula. However, at times, cohorts from the Praetorian Guard did participate in campaigns outside of Italy to quell rebellion among the legions or to participate as elite troops in important campaigns, especially when the emperor himself was the commanding general. They would also participate as armed envoys on special diplomatic missions. In Rome itself, the guard served as an urban police force, sometimes working with the city militia to police the numerous forms of spectacle (chariot racing, gladiatorial combat, beast hunts, athletic contests, and theater) as event security or quell riot when crowds got out of control.  The Praetorians also served as reserve firefighters when the ubiquitous small conflagrations that plagued Rome got out of control, most notably saving the Temple of Vesta from the “Great Fire” of 64 CE.

The Praetorian Guard was usually made up of highly decorated veterans (evocati) who served as both infantry (turmae) and cavalry (equitatae) in nine double strength cohorts of five hundred men.  As elite soldiers, they receive special benefits including a pension after sixteen years, as well as fifty percent more pay. They were also exempted from mundane camp duties and received a greater share of war treasure on campaign. Outside of Rome’s walls infantry guardsmen were armed and armored in a manner identical to their legionary comrades with their panoply consisting of a short sword (gladius), a rectangular shield (scutum), helmet (galea) banded body armor (lorica segmentata) and javelins (pila). Cavalry guardsmen were armed with longer swords (spatha), javelins, or thrusting spears (hasta), mail body armor (lorica hamata) and an oval shield. Praetorian shields were often emblazoned with specific emblems, most notably scorpions, winged thunderbolts with moon and stars, or alternately, a pattern of vine tendrils. Otherwise, it is often difficult to distinguish the Praetorians from their legionary comrades in the artwork of the period as they wore similar panoplies. However, within Rome’s walls, the Praetorian Guard were usually not allowed to be armored, instead wearing civilian garb (cohors togata) similar to the attire of Republican era lictors, who also served as bodyguards for Roman magistrates. Here, the Praetorians escorted the emperor in his official duties to the forum or to the theater, and to temples for religious sacrifice. When fulfilling these duties, they wore the cohors togata wrapped in a military belt with gladius and carrying a pilum. In inclement weather, they donned a hooded cloak or paenulae. However, there are some instances of the Praetorian Guard in full kit within the city walls in order to intimidate the Senate or the populace, as when Tiberius held a parade of the guard in 25 CE. The Roman historian Tacitus (56-120) records in his Annals that most of the initial guardsmen were recruited near the capital in the central Italian regions of Latium, Etruria, and Umbria. Later, the rest of the peninsula would be represented, however, other sources suggest that only ten percent of the force were recruited from the provinces, a much lower percentage than the legions. However, like most things Roman in antiquity, many guardsmen were able to secure admission because of family or political connections.

The Praetorian Guard’s leadership and organization took shape during the Julio-Claudian dynasty (31 BCE-69 CE). In 2 BCE Augustus appointed two Praetorian Prefects (praefectus praetorio) to command the guard, however, under his successor Tiberius (r.14-37) these positions were consolidated into one, with the emperor favoring the counsel of a prefect named Sejanus who greatly increase the power of the Praetorian Guard by controlling information to and from Tiberius and eliminating the emperor’s rivals. This was done through the use of some three hundred speculatores under the command of the Praetorian Prefect. These men served as the emperor’s mounted couriers to and from the provinces and as special agents for targeted assassinations. Sejanus was also responsible for the construction of Castra Praetoria, the fortified imperial barracks built outside of Rome’s walls northeast of the city. The Praetorian Guard became powerful enough to figure prominently in the direct selection of emperors. Tiberius’ adopted son, Caligula (r.37-41), was championed by a powerful Praetorian Prefect who secured his succession, and in return, Caligula expanded the guard from nine to twelve cohorts. It was this same imperial bodyguard who eventually assassinated Caligula just five years later. Ironically, the murder of the emperor threatened the continuation of the very empire that employed the Praetorians, so the frantic guardsmen found and “raised to the purple” Caligula’s uncle, Claudius (r.41-54). Claudius rewarded their fealty with a bonus (donativum) worth five times their annual salary. Moving forward, these money bonuses to the Praetorians became normal at the ascension of a new emperor. When Claudius was poisoned, the Praetorians switched their allegiance to Nero (r.54-68), whose mismanagement of imperial funds and strange personal habits led to his suicide and a brief period of civil war known as the “Year of Four Emperors” in 68-69 where the Praetorians again played an important part. The first claimant Galba refused to bribe the guardsmen and was hanged, while the second Otho paid the Praetorians’ price, only to be defeated by a third claimant, Vitellius, who then replaced them with loyal troops. These former Praetorians aided the popular general Vespasian who marched on Rome and defeated the new guardsmen, securing control of Rome.

Right: The Praetorians Relief from the Arch of Claudius. Louvre-Lens Museum. Lens, France. Source: Wikimedia.

Under the Flavian dynasty (69-96) and the reign of the “Five Good Emperors” (96-180) the Praetorian Guard enjoyed a period of stability and enhanced prestige as the emperor’s personal bodyguard in Rome and on campaign. The number of Praetorian cohorts was reduced to ten where it would remain until the early fourth century, however, the size of the cohorts would vary over time. During the reign of Trajan (98-117) more mounted security was added to the emperor’s protection detail. Known as equites singulares, this unit five hundred strong were carefully picked men recruited from Germans and Pannonians who had already been serving as noncitizen auxilia with the legions. This cavalry stood in the same sort of relation to the Praetorians as auxiliary stood to legionaries. Trajan’s creation of this corps was his way of showing honor to the auxiliaries of the empire and demonstrating that he trusted these men with the preservation of his own person. It also served as insurance in the event his Praetorian Guard betrayed him. Despite this precaution, the Praetorian Guard served Trajan well on campaign, and their likeness was carved in marble in his famous war memorial, Trajan’s Column, celebrating his victory of the Germanic Dacians and expansion of the Roman frontier north of the Danube River.

Marcus Aurelius’ death in 180 ended the reign of the “Five Good Emperors” and the abandonment of adopted successors who are capable emperors. Aurelius’ son Commodus proved an unworthy successor, and with his assassination in 193, Rome was once again faced with a succession crisis.  Known as the “Year of the Five Emperors,” five men claimed the title of Roman emperor: Pertinax, Didius Julianus, Pescennius Niger, Clodius Albinus, and Septimius Severus, and similar to the crisis of 68-69, the Praetorian Guard figured prominently in endorsing rival claimants.  In the end, Septimius Severus (r.193-211) prevailed, but his distrust of the existing Praetorian Guard led him to dismiss it and reform it with loyal soldiers from legions across the empire. He also doubled the cohort size from 500 to 1000 men and the entire guard from 11,500 to 30,000 men.

With the reign of Severus Rome entered a period of military monarchy, where military officers replaced civilian administrators across the empire. According to the Roman historian Cassius Dio (155-235), Severus was controlled by his powerful Praetorian Prefect, Gaius Fulvius Plautianus, who was eventually murdered by Severus’ son and co-ruler Caracalla (r.198-217) for intriguing against the Empress Julia. The Severan dynasty marks the beginning of a tumultuous third century in Rome, where assassination and civil war plagued the Empire. There was a succession of twenty-two emperors over the fifty-year period with only two dying of natural causes. The others died on military campaign or by assassination, with the Praetorian Guard featuring prominently in the latter, leading to the murder of several short-reigned emperors (Elagabalus in 222, and Balbinus and Maximus Thrax in 238) in yet another time of civil war known as the “Year of Six Emperors.”  This chaos continued with Rome suffering two break-away empires in the West and East, the Gallic Empire centered in Gaul, Spain, and Britain, and Palmyrene Empire in the Levant and Egypt. Imperial borders were finally restored by Aurelian (r.270-275), while true stability was restored by another general-made-emperor, Diocletian (r.284-305). Diocletian reorganized the empire through the creation of the tetrarchy or “rule of four,” thereby splitting the empire into the West and the East with each half ruled by two rulers, and Augustus and a Caesar in an attempt to restore the stability witness during the reign of the “Five Good Emperors.”  Under this powerful emperor, the Praetorian Guard was also split into four contingents, with each contingent guarding the augusti and caesars of East and West.

Right: . Imperial equites singulares escort Emperor Trajan on his Dacian Campaign. Trajan’s Column, Rome. Source: Wikimedia.

Diocletian’s tetrarchy was an imperfect solution in a time of ambitious men. In order to secure complete control over the Western Roman Empire, Augustus of the West Constantine marched on Rome and defeated the newly promoted Caesar of the West Maxentius and his Praetorian Guard at the battle of Milvian Bridge in 312. The early Christian author Lactantius (240-320) record Maxentius’s forces being pushed back against the river and retreating across a pontoon bridge assembled before the battle. The weight of soldiers fleeing caused the makeshift span to collapse, stranding elements of the guard on the northern bank of the river who were either killed or taken prisoner. The surviving guardsmen were sent in exile to the corners of the empire, and the Castra Praetoria was dismantled in a display that marked the official end of the Praetorian Guard’s three centuries of service. Still requiring personal protection, Constantine created a special imperial guard modeled on Trajan’s equites singulares called the scholae palatinae consisting of elite cavalry regiments five hundred strong recruited from Germanic troops. The idea of an exclusively foreign-born personal bodyguard loyal to coin more than nationality would continue into the medieval era with Scandinavian troops serving Anglo-Saxon kings (Huscarls) and Byzantine emperors (Varangians). Constantine would spend the next twelve years waging war against the remnants of the tetrarchy in the East until 324 when he was the sole master of Rome as Constantine “the Great” (r.324-337). After Constantine, the empire split into two halves, with the Western Empire facing internal divisions, economic decline, and barbarian invasion and settlement, while the Eastern Empire, in a stronger strategic and economic position, slowly transitioned into the Byzantine Empire, with its new capital of Constantinople (formerly Byzantium), a city elevated by Constantine for that very purpose.

The Praetorian Guard was an elite military force that existed for over three centuries of Roman history, bridging Pax Romana (31 BCE-180 CE), through the chaotic third century, and to the beginning of the division of empire. Adapted from Republican institutions by Caesar Augustus, it evolved from its primary role of imperial bodyguard to perform security tasks in the city of Rome, making it an essential part of the lives of Roman inhabitants when the “Eternal City” was the largest metropolis in the world. Bodyguard, soldiers, police officers, spies, and influence brokers, the Praetorian Guard holds a unique place in the history of Rome.

Suggested Readings:

Primary sources 

Cassius Dio. Dio’s Roman history in six volumes. Translated by Herbert Baldwin Foster.  Halcyon Pres, 2010. 

Suetonius. The Twelve Caesars. Translated by Robert Graves. Rosetta Books, 2014. 

Tacitus. The Annals. Translated by Cynthia Damon. Penguin Classics, 2013.

Secondary sources

Bingham, Sandra. The Praetorian Guard: A History of Rome's Elite Special Force. Baylor University Press, 2013. 

Davies, Roy. Service in the Roman Army. Edited by David Breeze and Valerie Maxfield. Columbia University Press, 1989. 

Grant, Michael. The Armies of the Caesars. Charles Scribner, 1979.