The Praetorian Guard was a handpicked unit of the Roman army formed by Augustus to ensure his own security. The close relationships between the emperor and the guard empowered the Praetorians to exert considerable influence on politics. While safeguarding the emperor against his enemies, the Praetorians were also powerful enough to overthrow a ruler that did not suit them. Emperors, as a rule, spared no expense to gain their support.
The Praetorian Guard goes all the way back to the customs of the era of the Roman Republic. At that time, a Praetorian cohort comprised friends, younger relatives, clients, and freedmen of a commander, who would accompany him around the province and formed his retinue, guard and council. Such a cohort included many young noblemen hoping to gain experience in military service, come to fame, and get beneficial connections and acquaintances under the command of their patron.
During the Civil Wars, the meaning of the term somewhat changed. It started to be applied to units of select soldiers who served as bodyguards of the commander while being used as shock reserve troops on the battlefield, capable of tipping the scale in favor of their leader. Gnaeus Pompeius, Gaius Julius Caesar, then Gaius Caesar Octavian, Mark Antony, and Lucius Aemilius Lepidus operated their own Praetorian cohorts, consisting of volunteer veterans who were personally loyal to their warlords.
After defeating the Republicans at the Battle of Philippi in 42 B.C., 8,000 of those veterans volunteered to continue their service. They were assigned to eight cohorts, half of which went to Caesar Octavian and the other half to Antony. In 36 B.C., Aemilius Lepidus’ army, including his Praetorian cohort, defected to Octavian. At the Battle of Actium in 31 B.C., Octavian had five Praetorian cohorts and Antony had four.
When Antony’s army defected to Octavian after its commander fled, Octavian joined his newly acquired Praetorian units with those of his own, which was to symbolize the reunification of Caesar’s army. The number of Octavian’s Praetorian cohorts thereby increased to nine.
The pillar and stronghold of imperial power
After the Civil Wars, Octavian, or Augustus as he came to be known after 27 B.C., retained the Praetorian cohorts which had previously been run by him, turning them into the foundation of his rule. Augustus kept three of them in Rome, whereas six more were quartered in the surrounding towns of Latium. Romans gradually got accustomed to seeing armed men in city streets, which ran counter to the political and religious regulations of the Republican era.
Following Augustus’ demise, his successor Tiberius brought all of the Praetorian cohorts together in Rome in 23 A.D. and to this end built a common camp for them in the northern part of the city, between the hills of Viminalis and Esquilinus. Assembled together, the Praetorians became a formidable force that intimidated the emperor’s internal opponents and was able to ensure his protection in case of civil unrest in the capital or should military revolts erupt in the provinces.
The Praetorians guarded the palatial estate on the Palatine Hill, as well as accompanied the emperor in the streets of Rome and whenever he participated in various solemn events or religious ceremonies. The guard left Rome in a single unit when the emperor would lead his army to undertake a military campaign or to conquer yet another province. Inscriptions indicate that Praetorian units were also engaged to fight outlaws who were plaguing Italy at the time.
To effectively command his Praetorian guard, the emperor appointed one or two prefects of a praetorium from among the equites. This position was regarded as the highest office in the empire and became the crowning achievement of a knight’s career. The Praetorian prefects enjoyed considerable power because of their proximity to the emperor. They were part of the imperial council and gradually acquired administrative and judicial powers. Their department financed military expenditures, dealt with supplies and provisioning, recruitment, and the promotion of the officer corps.
The prefect of a praetorium exercised supreme command in the course of large-scale military operations, whereas in the emperor’s absence, he ruled Italy and Rome. The extent of the extraordinary powers that prefects concentrated in their hands often enabled them to manipulate weaker emperors or even overthrow them and usurp power.
Numbers and structure
In 23 A.D., according to Tacitus, the Praetorian Guard consisted of nine cohorts. In the reign of Caligula or Claudius, their number rose to twelve. In 69 A.D., Vitellius dispersed the old guard and recruited 16 new cohorts, each 1,000 strong. Vespasian again restored the Praetorian Guard as it had operated under Augustus by reducing the number of cohorts to nine. In the reign of Domitian or Trajan, a tenth cohort was added, and thereafter the number of cohorts remained unchanged until the reign of Septimius Severus.
Scholars remain divided as to the number of soldiers in a cohort, since literary and epigraphic sources are rather unclear. Although Dio Cassius writes that as early as during Augustus’ reign a cohort numbered 1,000 soldiers, he erroneously writes about 10 cohorts. It looks like he was simply describing the order that existed shortly before his own time. Some historians, however, are inclined to trust these figures, while others are of the opinion that originally the number of soldiers in a cohort would not exceed 500.
One of the arguments in this dispute is the area of the camp on the Viminal Hill, which hosted the nine Praetorian cohorts and additionally three cohorts of the city guards starting in 23 A.D. It amounts to 16.72 hectares, which roughly corresponds to the area occupied by a legion, meaning that a Praetorian cohort, at least initially, must have numbered 500 rather than 1,000 soldiers.
A Praetorian cohort used to be a mixed unit consisting of infantrymen and horsemen. Each cohort consisted of six centuriae of foot soldiers, numbering from 60 to 80 men, led by a centurion. Furthermore, the cohort included three turmae, 30 riders each. Those riders were formally listed in the cohorts, to which they were assigned, but at the same time they formed a special corps of 900 people under the command of a special optio (optio equitum) as part of the guard. In peacetime they served as messengers and couriers. A regular soldier was enabled to become a horseman after five years of service.
Another select unit of the Praetorian cavalry comprised 300 so-called “scouts” (speculatores) — the most faithful soldiers who were to serve directly under the emperor. That detachment was also headed by a special centurion, having the title of the trecenarius.
The title of the second most senior centurion was “camp commander” (princeps castrorum). The other centurions of the guard, in contrast with the rules adopted in the legions, had equal status and enjoyed equal pay.
The number of soldiers in the Guard gradually increased, primarily due to the increase in the number of centurions and turmae within each cohort. During the last two decades of the 1st century A.D. and throughout most of the 2nd century A.D., the number of centuriae in each cohort gradually increased from six to ten, whereas the number of turmae went up from three to five. The strength of each cohort thereby almost doubled from 500 to nearly 1,000 soldiers. While under Augustus the number of the Praetorian Guard was 4,500 men, Vespasian brought it up to 7,200 soldiers, Domitian further expanded the Guard to 8,000 men, under Commodus it was as large as 10,000 men, and Septimius Severus eventually increased it to 15,000.
The Praetorian Guard originally enjoyed the status of a specially picked military unit, and its soldiers were awarded considerable privileges. The length of service of the Praetorians was set at 16 years, rather than 25, which was common for regular soldiers of legions. In terms of pay, the Praetorians received 750 denarii during Augustus’ reign; this basic rate remained unchanged until Domitian, who increased it to 1,000, 130% higher than the pay of a regular legionary.
In addition, upon ascending the throne, each emperor made sure to pay the Praetorians an amount equal to five years’ worth of their standard pay in order to gain their loyalty. From time to time, emperors would also pay general bonuses to celebrate a decade or two of their reigns, weddings or adoptions into the ruling house, victories they won, or to commemorate other solemn events. In Augustus’ will, after his death each soldier received a gift of 2,500 denarii in the year 14 A.D. His example was followed by Tiberius, who ruled after him, and then Caligula ordered that amount to be doubled. Claudius, on his accession to the throne, commanded that 3,750 denarii be given to each of the Praetorians. In addition, he ordered that pecuniary gifts be given to soldiers once Nero reached his legal age.
Career opportunities for the Praetorians were vast and truly tempting. After four years of service, a regular soldier was able to become a “scout” or be transferred to the cavalry units that were an integral portion of each cohort. After that, there were possibilities of being promoted to one of the positions of junior commanders, or principals, which envisaged one-and-a-half, double, and then triple pay.
Each centuria had three full-time positions for principals: the signifer carried its battle banner or signum, the tesserarius walked the posts, and the optio was the deputy and aide to the centurion. Principals also worked in the prefect’s office at the praetorium as clerks, note-takers, and bookkeepers. The crowning achievement of a principal’s career was the position of the centurion.
The Praetorians who had risen to the ranks of senior principals were seamlessly promoted to centurions in the army or in one of the Roman city cohorts, retiring honorably after 16 years of service and then opting for extended service as an evocatus. Then they could either — while staying in the army — gradually climb up the centurion’s career, aiming at the position of the primipilus (the highest-ranking centurion in a legion), or, after several years of service as a centurion of a city cohort, choose to be transferred to the guard and take the post of a centurion in the Praetorian cohorts. Statistics show that in the middle of the 2nd century A.D., about 30 percent of centurions in legions stemmed from the Praetorian Guard.
Recruitment to the guard
Excellent career prospects, proximity to the imperial court, enviable pay, luxurious attire and military gear served as a magnet for ambitious young men to seek service in the Praetorian Guard and made it possible to recruit volunteers. Patronage and letters of recommendation played a decisive role in recruitment. Preference was given to Italian municipal nobility and the middle class.
The dominance of “natives” of the Praetorian Guard in the posts of centurions of the provincial legions allowed the Italian character of the officer corps of the Roman army to be maintained across the ranks. Tacitus reported that in the early 1st century A.D. most Praetorians came from Latium, Etruria and Umbria, as well as the old Roman colonies. Many inscriptions fundamentally corroborate this data. Bonogna, Faesulae, Cremona, Mutina, Florence, Perusia, and Venafro appear as the places of origin of a large proportion of the soldiers. The demobilization list of the Praetorians dating from 136 A.D. shows that 89 percent of those mentioned in it were of Italian descent, while 11 percent were from provinces. Half of the latter were from Pannonia, the rest came from Tarraconian Spain, Noricum, and Macedonia.
The proportion of provincials in the Roman guard gradually increased to eventually reach half of its total strength by the end of the 2nd century A.D. Finally, in 193 A.D., Septimius Severus dispersed the old guard and began to recruit a new unit from the distinguished soldiers of provincial legions. Cassius Dio, a contemporary of those events, describes the harsh impression they produced on Romans:
“Now he did this with the idea that he should thus have guards with a better knowledge of the soldier’s duties, and should also be offering a kind of prize for those who proved brave in war; but, as a matter of fact, it became only too apparent that he had incidentally ruined the youth of Italy, who turned to brigandage and gladiatorial fighting in place of their former service in the army, and in filling the city with a throng of motley soldiers most savage in appearance, most terrifying in speech, and most boorish in conversation…”
Weapons and appearance
Neither the Praetorian Guard nor the Roman army in general had any standard uniform or statutory consistency of attire and military gear. When accompanying the emperor to war or whenever there was a threat of emergency, soldiers would wear armor. It is only possible to judge what kind of armor they wore from the images that have survived.
Monuments such as the relief from Claudius’ now-defunct triumphal arch that can be found in the Louvre or a number of images from Trajan’s Column indicate that the Praetorians wore the same armor and weapons as all other soldiers, perhaps only more luxuriously decorated. During solemn rides or sacrifices, soldiers left their armor in the camp and wore festive attire, wielding laurel branches in their hands. Describing their appearance, Herodian mentions belts with short swords decorated with gold and silver, which the Praetorians wore on their left side.
The Praetorians performed their duties as guards around the imperial palace on the Palatine, in the theater, the circus, or the Colosseum while dressed in civilian clothes, including a toga, under which they hid a sword.
Fate of the Guard
The Praetorian Guard appeared to play a crucial role in politics. The Praetorians maintained unquestioning loyalty to Augustus and Tiberius. In 41 A.D., a tribune of the Guard, Cassius Chaerea, killed insane Caligula, after which the guardsmen proclaimed Claudius as new emperor. During the crisis of 69 A.D., the Praetorians operated as an active force, first supporting Galba against Nero, then eliminating Galba and transferring the throne to Otho, and then supporting Vespasian against Vitellius.
After the assassination of Emperor Commodus in 193 A.D., the guard again intervened in politics, first supporting and then killing Pertinax. The Praetorians even had an auction in their camp, offering the throne to the highest bidder. As punishment for that shameful act, Septimius Severus disbanded the guard and replaced it with his Illyrian soldiers. The power of the Praetorians peaked during the crisis of the 3rd century A.D., when they supported emperors one day and overthrew them another day at their discretion.
The defeat of the Guard’s protégé Maxentius by Constantine at the Milvian Bridge in 312 A.D. became fatal for the Praetorians. Constantine ultimately disbanded the Praetorian cohorts, replacing them with alternative guard units.
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