The Praetorian Guard (Latin: cohortes praetorianae) was an elite unit of the Imperial Roman army whose members served as personal bodyguards to the Roman emperors. During the era of the Roman Republic, the Praetorians served as a small escort force for high-ranking officials such as senators or provincial governors like procurators. With the republic's transition into the Roman Empire, however, the first emperor, Augustus, founded the Guard as his personal security detail. Although they continued to serve in this capacity for roughly three centuries, the Guard became notable for its intrigue and interference in Roman politics, to the point of overthrowing emperors and proclaiming their successors. In 312, the Guard was disbanded by Constantine the Great.
The designation originated during the Roman Republic, for the guards of Roman generals as early as the rise to prominence of the Scipio family around 275 BC. There was no permanent guard charged with the protection of military general officers; however, certain military officers chose to surround themselves with guards to ensure their security. For example, during the Siege of Numantia, Scipio Aemilianus formed a troop of 500 men for his personal protection, as sorties were often quite dangerous for the upper ranks. This usage was then emulated and spread, as Roman generals occupied their positions for longer periods of time. Accordingly, this guard was referred to as Cohors Prætoria. In the event of battle, these cohorts would intervene as a final standing reserve. The consuls were ordinarily protected by the lictors, who would remain around their tents in the army.
At the end of the year 40 BC, Octavian (the future Augustus) and his rival Mark Antony both operated a number of Praetorian units organized individually. According to Appian, amongst them were veterans forming cohorts. Antony commanded three cohorts in the Orient and in 32 BC, he issued coins in honor of his Praetorians. According to Paul Orose, Octavian commanded five cohorts at Actium.
Following his victory at Actium, Octavian merged his forces with those of his adversary in a symbolic reunification of the Army of Julius Caesar.
The legionaries known as the Praetorian Guard were first hand-picked veterans of the Roman army who served as bodyguards to the emperor. First established by Augustus, members of the Guard accompanied him on active campaign and served as secret police protecting the civic administrations and rule of law imposed by the senate and the emperor. The Praetorian Guard was ultimately dissolved by Emperor Constantine I in the 4th century. They were distinct from the Imperial German Bodyguard which provided close personal protection for the late Western Roman emperors.
They benefited from several advantages due their close proximity with the emperor: the Praetorians were the only ones admitted while bearing arms in the center of sacred Rome – the Pomerium. Their mandatory service was shorter in duration, for instance : 12 years with the Praetorians instead of 16 years in the legions starting year 13 BC, then carried to, respectively, 16 to 20 years in year 5 BC according to Tacitus, and their pay was more elevated than that of a legionary. Under Nero, the pay of a Praetorian was three and a half times that of a legionary, augmented by prime additions of donativum, granted by each new emperor. This additional pay was the equivalent of several years of pay, and was often repeated at important events of the empire, or events that touched the imperial family: birthdays, births and marriages. Major monetary distributions or food subsidies renewed and compensated the fidelity of the Praetorians following each failed particular attempted plot (such as that of Messalina against Claudius in AD 48 or Piso against Nero in AD 65). Feared and dreaded by the population and by the Roman Senate, the Praetorians got no shred of sympathy from the Roman people. A famous poem by Juvenal recalls the nail left in his foot by the sandal of a Praetorian rushing by him. "Praetorian" has a pejorative sense in French, recalling the often troubling role of the Praetorian of antiquity.
The Praetorians received substantially higher pay than other Roman soldiers in any of the legions, on a system known as sesquiplex stipendum, or by pay-and-a-half. So if the legionaries received 250 denarii, the guards received 375 per annum (year). Domitian and Septimius Severus increased the stipendum (payment) to 1,500 denarii per year, distributed in January, May and September.
In ancient Rome, praetors were either civic or military leaders. The praetorianus were initially elite guards for military praetors, under the Republic. As the Republic ended, the first emperor, Augustus, set up an elite guard of praetorianus to protect himself.
The early Praetorian Guard differed greatly from that in later times, which came to be a vital force in the power politics of Rome. While Augustus understood the need to have a protector in the maelstrom of Rome, he was careful to uphold the Republican veneer of his regime. Thus, he allowed only nine cohorts to be formed, each originally consisting of 500 men. He then increased them to 1,000 men each, but allowed three units to be kept on duty at any given time in the capital. A small number of detached cavalry units (turmae) of 30 men each were also organized. While they patrolled inconspicuously in the palace and major buildings, the others were stationed in the towns surrounding Rome. This system was not radically changed with the appointment by Augustus in 2 BC of two Praetorian prefects, Quintus Ostorius Scapula and Publius Salvius Aper, although organization and command were enhanced. Tacitus reports that the number of cohorts was increased to twelve from nine in AD 47. In AD 69 it was briefly increased to sixteen cohorts by Vitellius, but Vespasian quickly reduced it again to nine.
In Rome, their principal duty was to mount the Guard at the house of Augustus on the Palatine, where the centuries and the turmae of the cohort in service mounted the guard outside the emperor's palace (the interior guard of the palace was mounted by the Imperial German Bodyguard, often also referred to as Batavi, and the Statores Augusti, a sort of military police which were found in the general staff headquarters of the Roman Army). Every afternoon, the serving tribune of the cohort would receive the password from the emperor personally. The command of this cohort was assumed directly by the emperor and not by the Praetorian prefect. After the construction of the Praetorian camp in 23 BC, there was another similar serving tribune placed in the Praetorian camp accordingly. Their functions included, among many, the escort of the emperor and the members of the imperial family, and if necessary to act as a sort of anti-riot police. Certain Empresses commanded exclusively their own Praetorian Guard.
According to Tacitus, in the year 23 BC, there were nine Praetorian cohorts (4500 men, the equivalent of a legion) to maintain peace in Italy; three were stationed in Rome, and the others, nearby.
Their mandatory service period was shorter than that of the legionaries: 12 years with the Praetorians instead of 16 years in the legions in 13 BC: these were increased respectively to 16 and 20 years in year 5 BC according to Tacitus, and their pay was higher than that of a legionaries.
An inscription recently discovered suggests that, towards the end of the reign of Augustus, the number of cohorts increased to 12 during a brief period. This inscription referred to one man who was the tribune of two successive cohorts: the eleventh cohort, apparently at the end of the reign of Augustus, and the fourth at the beginning of the reign of Tiberius. According to Tacitus, there were only nine cohorts in 23 AD. The three urban cohorts, which were numbered consecutively after the Praetorian cohorts, were removed near the end of the reign of Augustus; it seemed probable that the last three Praetorian cohorts were simply renamed as Urban Cohorts.
The first intervention of the Praetorians on a battlefield since the wars of the end of the Republic took place during the mutinies of Pannonia and the mutinies of Germania. On the death of Augustus in AD 14, his successor Tiberius was confronted by mutinies in the two armies of the Rhine and Pannonia, who were protesting about their conditions of service, in comparison with the Praetorians. The forces of Pannonia were dealt with by Drusus Julius Caesar, son of Tiberius (not to be confused with Nero Claudius Drusus, brother of Tiberus), accompanied by two Praetorian cohorts, the Praetorian Cavalry, and Imperial German Bodyguards. The mutiny in Germania was repressed by the nephew and designated heir of Tiberius, Germanicus, who later led legions and detachments of the Guard in a two-year campaign in Germania, and succeeded in recovering two of the three legionary eagles which had been lost at the Battle of the Teutoburg Forest.
It was under Tiberius that Lucius Aelius Seianus (Sejanus) rose in power and was among the first prefects to exploit his position to pursue his own ambitions. He concentrated under his command all the Praetorian cohorts in the new camp. Sejanus held the title of prefect jointly with his father, under Augustus, but became sole prefect in AD 15. He used that position to render himself essential to the new emperor Tiberius, who was unable to persuade the Senate to share the responsibility of governing the Empire. Sejanus, however, alienated Drusus, son of Tiberius, and when the heir to the throne, Germanicus, died in AD 19, he was worried that Drusus would become the new emperor. Accordingly, he poisoned Drusus with the help of the latter's wife, and then immediately launched a ruthless elimination program against all competitors, persuading Tiberius to make him his heir apparent. He almost succeeded, but his plot was discovered and revealed in AD 31 and he was subsequently killed. Emperor Tiberius used for this purpose the Cohortes urbanae which were not under the control of Sejanus.
In AD 37 Caligula became emperor with the support of Naevius Sutorius Macro, Sejanus' successor as prefect of the Praetorian Guard. Under Caligula, whose reign lasted until AD 41, the overall strength of the Guard increased from 9 to 12 Praetorian cohorts.
In year 41, it was disgust and hostility of a praetorian tribune, named Cassius Chaerea – whom Caligula teased without mercy due to his squeaky voice – which led to the assassination of the emperor by officers of the guard. While the Imperial German Bodyguard sacked all in a search to apprehend the murderers, the Senate proclaimed the restoration of a Republic. The Praetorians, which were pillaging the Palace, discovered Claudius, uncle of Caligula, hidden behind a curtain. Needing an emperor to justify their own existence, they brought him forth to the Praetorian camp and proclaimed him emperor. He is the first emperor proclaimed by the Praetorian Guard and compensated the guard with a prime bonus worth five years their salary. The Praetorians accompanied Emperor Claudius to Britain in 43 AD.
When Claudius was poisoned, the Guard transferred their allegiance to Nero through the influence of his Praetorian prefect Sextus Afranius Burrus, who exercised a beneficial influence on the new emperor during the first five years of his reign. Officers of the Guard, including one of the two successors of Burrus as the Praetorian prefect, participated in Piso's conspiracy in year 65. The other Praetorian prefect, Tigellinus, headed the suppression of the conspiracy, and the Guard was compensated with a bonus of 500 denarii for each man.
In AD 69, the new colleague of Tigellinus, Nymphidius Sabinus, managed to have the Praetorian Guard abandon Nero in favor of the contender Galba. Nymphidius Sabinus, had promised 7500 denarius per man, but Galba refused to pay that amount because he stated "It is my habit to recruit soldiers and not buy them". This permitted his rival Otho to bribe 23 Speculatores of the Praetorian Guard to proclaim him emperor. Despite the opposition of the cohorts in service in the palace, Galba and his designated successor, the young Pison, were lynched on January 15.
After supporting Otho against a third contender Vitellius, the Praetorians were restrained following defeat and their centurions executed. They were replaced by 16 cohorts recruited from the legionnaires and auxiliaries loyal to Vitellius, almost 16,000 men. These ex-Praetorians then aided Vespasian, the fourth Emperor, leading the attack against the Praetorian camp.
Under the Flavians, the Praetorians formed 9 new cohorts, of which Titus, son of the emperor Vespasian, became the prefect. Vespasian returned the effective strength of each unit to five hundred men. He also cancelled the guard service of the Praetorians at the entry to the emperor's palace, but retained guards within the palace itself.
Under Vespasian's second son, Domitian, the number of cohorts was increased to 10, and the Praetorian Guard participated in fighting in Germania and on the Danube against the Dacians. It was in the course of these actions that the prefect Cornelius Fuscus was defeated and killed in 86.
Following assassination of Domitian in 96 the Praetorians demanded the execution of their prefect, Petronius Secundus, who had been implicated in the murder. The Guard supported Trajan, commander of the Army of the Rhine, as new emperor.
At the death of Nerva, at the beginning of 98, Trajan executed the remaining Praetorian prefect and his partisans. Trajan returned to Rome from the Rhine, probably accompanied by the new unit of equites singulares Augusti. The Praetorian Guard had participated in the two Dacian Wars of Trajan (Dacian Wars 101–102 and 105–106). The Praetorian Guard served in the last campaign of Trajan against the Parthians of 113–117.
During the 2nd century, the Praetorian Guard accompanied Lucius Verus in the Oriental War Campaign of 161–166 AD, as well as accompanying Roman Emperor Marcus Aurelius in his northern campaigns between 169–175 and 178–180. Two prefects were killed during these expeditions.
With the accession of Commodus, in 180, the Praetorian Guard returned to Rome. Tigidius Perennis (AD 182–185) and freedman Marcus Aurelius Cleander (AD 186–190) exercised considerable influence on the emperor. Perennis was killed by a delegation of 1500 persons of Great Britain which came forth to complain about his interference in the affairs of the province (a delegation of Lanciarii of the 3 legions of Great Britain). Cleander abused his influence to nominate and dismiss prefects.
In 188, Cleander obtained the joint command of the Guard with the two prefects. Cleander ordered a massacre of civilians carried by the equites singulares Augusti which led to an arranged battle with the Urban Cohorts.
Commodus fell victim to a conspiracy directed by his Praetorian prefect Quintus Aemilius Laetus in 192. The new emperor Pertinax, who took part in the conspiracy, paid the Praetorians a premium of 3,000 denarii; however he was assassinated three months later, on March 28 193, by a group of Guards. The Praetorians then put the empire up to auction and Didius Julianus bought the title of emperor. However the armies of the Danube chose instead the governor of Pannonia Superior, Septimius Severus, who besieged Rome and tricked the Praetorians when they came out unarmed. The Praetorian Guard was dissolved and replaced by men transferred from his own army.
The new Guard of Septimius Severus made their mark against his rival Clodius Albinus at the Battle of Lyon in 197, and accompanied the emperor to the Orient from 197 to 202, then to Britannia from 208 until his death at York in 211.
Caracalla, son of Septimius Severus, lost favour with his troops by assassinating his own brother and co-emperor, Geta, immediately after his succession. He also created problems by trying to recreate a Macedonian phalange witnessed previously in the Roman Army. Finally, in 217, while on campaign in the Orient, he was assassinated at the instigation of his prefect Macrinus.
After the elimination of the latter, the Praetorians made opposition to the new emperor Elagabalus, priest of the oriental cult of Elagabal, and replaced him by his 13-year old cousin Severus Alexander in 222.
In this period the position of Praetorian prefect in Italy came increasingly to resemble a general administrative post, and there was a tendency to appoint jurists such as Aemilius Papinianus, who occupied the post from 203 until his elimination and execution at the ascent of Caracalla. Under Severus Alexander the Praetorian prefecture was held by the lawyer Ulpian until his assassination by the Praetorian Guard in the presence of the emperor himself.
In the spring of 238, under Maximinus Thrax, the bulk of the Praetorian Guard was employed on active service. Defended by only a small residual garrison, the Praetorian camp was attacked by a civilian crowd acting in support of senators in revolt against the Gordian emperors. The failure of Maximinus Thrax to win the civil war against the contenders Gordian I and Gordian II let to his death at the hands of his own troops, including the Praetorians. The senatorial candidates for the throne, Pupienus and Balbinus, recalled the Praetorian Guard to Rome, only to find themselves under attack by the Praetorians. Both were killed on July 29 238 and Gordian III triumphed.
After 238, literary and epigraphic sources dry up, and information on the Praetorian Guard becomes rare. In 249, the Praetorians assassinated Philippus II, son of the emperor Philip the Arab. In 272, in the reign of the emperor Aurelian, they took part in an expedition against Palmyra. In 284, Diocletian reduced the status of the Praetorians; they were no longer to be part of palace life, as Diocletian lived in Nicomedia, some 60 miles (100 km) from Byzantium in Asia Minor. Two new corps, the Ioviani and Herculiani (named after the gods Jove, or Jupiter, and Hercules, associated with the senior and junior emperor), replaced the Praetorians as the personal protectors of the emperors, a practice that remained intact with the Tetrarchy. In 297 they were in Africa with Maximian. By the time Diocletian retired on May 1, 305, their Castra Praetoria seems to have housed only a minor garrison of Rome.
During the early 4th century, Caesar Flavius Valerius Severus attempted to disband the Praetorian Guard on the orders of Galerius. In response, the Praetorians turned to Maxentius, the son of the retired emperor Maximian, and proclaimed him their emperor on 28 October 306. By 312, however, Constantine the Great marched on Rome with an army in order to eliminate Maxentius and gain control of the Western Roman Empire, resulting in the Battle of the Milvian Bridge. Ultimately, Constantine's army achieved a decisive victory against the Praetorians, whose emperor was killed during the fighting. With the death of Maxentius, Constantine definitively disbanded the remnants of the Praetorian Guard. The remaining soldiers were sent out to various corners of the empire, and the Castra Praetoria was dismantled in a grand gesture inaugurating a new age in Roman history and ending that of the Praetorians.
While campaigning, the Praetorians were the equal of any formation in the Roman army. On the death of Augustus in 14 AD, his successor, Tiberius, was faced with mutinies among both the Rhine and Pannonian legions. According to Tacitus, the Pannonian forces were dealt with by Tiberius' son Drusus, accompanied by two Praetorian cohorts, the Praetorian cavalry and some of the German bodyguard. The German mutiny was put down by Tiberius' nephew and adopted son Germanicus, his intended heir, who then led the legions and detachments of the Guard in an invasion of Germany over the next two years. The Guard saw much action in the Year of the Four Emperors in 69, fighting well for Otho at the first battle of Bedriacum. Under Domitian and Trajan, the guard took part in wars from Dacia to Mesopotamia, while with Marcus Aurelius, years were spent on the Danubian frontier during the Marcomannic Wars. Throughout the 3rd century, the Praetorians assisted the emperors in various campaigns.
Praetorian Cohorts intervened on numerous occasions in the struggle for the imperial succession. Lacking troops of its own, the Senate had no choice each time but to accept the choice of the Praetorians as well as that of the various legions. The new emperor was always proclaimed by the Praetorians before being ratified by the Senate and the legions stationed in the various provinces.
After the death of Sejanus, who was sacrificed for the donative (imperial gift) promised by Tiberius, the Guards began to play an increasingly ambitious and bloody game in the Empire. For the right price, or at will, they assassinated emperors, bullied their own prefects, or turned on the people of Rome. In 41, Caligula was killed by conspirators from the senatorial class and from the Guard, along with his wife and daughter. The Praetorians placed his uncle Claudius on the throne, daring the Senate to oppose their decision. In 69, the Year of the Four Emperors, after the emperor Galba failed to provide a donative for the Praetorians, they transferred their allegiance to Otho and assassinated the emperor. Otho acquiesced in the Praetorians' demands and granted them the right to appoint their own prefects, ensuring their loyalty. After defeating Otho, Vitellius disbanded the Guard and established a new Guard sixteen cohorts strong. Vespasian relied in the war against Vitellius upon the disgruntled cohorts the emperor had dismissed, and reduced the number of cohorts back to nine upon becoming emperor himself. As a further safeguard, he appointed his son, Titus, as Praetorian prefect.
While the guard had the power to make or break emperors, it had no formal role in government administration, unlike the personnel of the palace, the Senate, and the bureaucracy. Often after an outrageous act of violence, revenge by the new ruler was forthcoming. In 193, Didius Julianus purchased the Empire from the Guard for a vast sum, when the Guard auctioned it off after killing Pertinax. Later that year Septimius Severus marched into Rome, disbanded the Guard and started a new formation from his own Pannonian legions. Unruly mobs in Rome often fought with the Praetorians in Maximinus Thrax's reign in vicious street battles.
In 271, Aurelian sailed east to destroy the power of Palmyra, Syria, with a force of legionary detachments, Praetorian cohorts, and other cavalry units, and easily defeated the Palmyrenes. This led to the orthodox view that Diocletian and his colleagues evolved the sacer comitatus (the field escort of the emperors). The sacer comitatus included field units that used a selection process and command structure modeled after the old Praetorian cohorts, but it was not of uniform composition and was much larger than a Praetorian cohort.
Starting in the year 2 BC, the Praetorian prefect was the commanding officer of the Praetorian Guard (previously each cohort was independent and under the orders of a tribune of equestrian rank). This role (chief of all troops stationed in Rome), was in practice a key position of the Roman polity.
From Vespasian onwards the Praetorian prefecture was always held by an equestrian of the eques order. (Equestrians were traditionally that class of citizens who could equip themselves to serve in the Roman Army on horseback.
From the year 2 BC, the cohorts were under the control of two prefectures; however cohorts continued to be organized independently, each commanded by a tribune. Tribunes had as immediate subordinates ordinary Centurions, all of equal rank except for the Trecenarius, the first and prime of all centurions of the Praetorian Cohorts, who commanded also the 300 speculatores, and with the exception of his second, the Prince Castrorum.
From the second century the Praetorian prefect oversaw not only the Praetorian Cohorts but also the rest of the garrison of Rome, including the Cohortes urbanae ("urban cohorts") and the equites singulares Augusti, but not the Vigiles cohorts.
Following the dissolution of the Praetorian Cohorts by the emperor Constantine after he defeated them at the Battle of the Milvian Bridge in 312, the role of the Praetorian prefect in the Empire became purely administrative, ruling large territories (prefectures) comprising Roman dioceses (geographical subdivisions of the Roman Empire) in the name of the Emperor.
In order not to alienate the population of Rome, while conserving Republican civilian traditions, the Praetorians did not wear their armor while in the heart of the city. Instead they often wore a formal toga, which distinguished them from civilians but remained in a respectable civilian attire, the mark of a Roman citizen. Augustus, conscious of risking the only military force present in the city, often avoided concentrating them and imposed this dress code.
From the reign of Tiberius, their camp was situated on the Quirinal Hill, outside Rome. In 26 AD, Sejanus, Praetorian prefect, and the favorite of emperor Tiberius, united the Urban Cohorts with nine Praetorian Cohorts, dispersed at that time throughout Italy, in one large camp situated beyond the Servian Wall, on the Esquiline Hill, the Castra Praetoria.
For the 2nd century, calculations from lists of significant demobilisations suggest an increase in size to nearly 1,500 men per cohort (perhaps a doubling of 800 (since Vespasian), probably organized in 20 centuries) under Commodus in year (187–188) or under Septimius Severus (193–211), which matches the probable numbers of effectives for Urban Cohorts during the time of Cassius Dio. These figures suggest an overall size for the Guard of 4,500–6,000 men under Augustus, 12,800 under Vitellius, 7,200 under Vespasian, 8,000 from Domitian until Commodus or Septimius Severus, and 15,000 later on.
At the beginning of the 2nd century, Italians made up 89% of the Praetorian Guard. Under Septimius Severus, recruitment evolved to authorize the inclusion of legionaries of the Roman army, as well as of the battle hardened Army of the Danube. Severus stationed his supporters with him in Rome, and the Praetorian Guards remained loyal to his choices.
Initially each cohort included, as for a Roman legion, a cavalry detachment; this should not be confused with the equites singulares Augusti who appeared under the emperor Trajan. The Praetorian could become a cavalryman (Eques) after almost five years service in the infantry. These Praetorians remained listed in their Centuries of origin, but operated in a turma of 30 men each commanded by an Optioequitum.
There was probably one turma of cavalry for two centuries of infantry. Hence, three turmae per cohorts of the Augustan period, five per cohort in 100 CE–200 CE, and ten per cohort after 200 CE, with a vexillum (flag) as emblem for each turma.
The speculatores Augusti were cavalrymen assigned to the same tasks as the Speculatores of the legions and the auxiliary units (messengers in charge of transmitting intelligence, and clandestine agents).
About 300 in total (30 per cohort), they formed a unit under the orders of the senior Centurion, the Trecenarius. Selected for their impressive physique, they were used by the Emperor for clandestine operations and tasks such as arrests, imprisonment, and executions.
One of their roles was to accompany the emperor on his foreign campaign journeys (a role which would later be handled by the Singulares/equites singulares Augusti). Claudius was in the habit of surrounding himself with Speculatores when attending dinners.
The close security protection detail of Galba, of Otho and the dynastic line of the Flavians appear to have been formed of Speculatores (who replaced the Imperial German Bodyguard disbanded by Galba).
Following the assassination of emperor Domitian, his successor Nerva was placed under the protection of Trajan, to counter possible revenge attempts and mutinies. Trajan was commander of the most important army of the time, that of the Army of Germania, and he nominated him as his heir. Accordingly, and following such an act, Trajan, aiming to reinforce his security detail in relation to the Speculatores who had remained loyal to Domitian, replaced them as close protection security detail with the Singulares/equites singulares Augusti (modelled on the Singulares of a provincial governor, a post held by Trajan). The some 300 Speculatores were reassigned by Trajan to the corps of Praetorian cohorts.
They were distinguished by a special (but unknown) style of boots, the Speculatoria Caliga (according to Suetonius) and they received special honorific diplomas in bronze at demobilization. They had their own Equestrian instructors (Exercitatores).
Originally, the Praetorian Guard was recruited from the populations of central Italy (Etruria, Umbria and Latium according to Tacitus). Recruits were between 15 and 32 years of age, compared to legionary recruits who ranged from 18 to 23 years of age. According to Cassius Dio, during the first two centuries AD and before the reform of Septimius Severus, the Praetorians were exclusively limited to Italy, Spain (Roman province), Macedonia and Noricum (current Austria).
Under the reign of Vitellius, and starting from Septimius Severus, men were transferred from the Urban Vigiles, Urban cohorts, and the various legions. This recent method and manner of recruitment at the corps of the legions became the normal procedure to recruit in the 3rd century after Septimius Severus dealt with the undisciplined Praetorians who assassinated Pertinax in 193, and replaced them with men from his own Danube legions.
At that time, the Praetorians represented the best soldiers from the legions (principally from Illyria). They were a group of elite of soldiers starting from the 3rd century, and not a category of socially privileged soldiers (such as the Italians at the time of Augustus). The Italians formed the base of the recruitment of the Legio II Parthica, a new legion created and stationed in Italy.
To be admitted to the Guard, a man had to be in good physical condition, governed by a Good moral character, and come from a respectable family. In addition, he had to make use of all sorts of patronages available to him in order to obtain letters of recommendations from important leading figures in society. Once past the recruitment procedure he was designated as Probatus, and assigned as a Miles (soldier) to one of the centuries of a cohort. After two years, if he attracted the attention of his superiors by influence or merit, he could attain the post of Immunis (similar to corporal), perhaps as a commis (junior chief) at general headquarters or as a technician. This promotion exempted him from daily chores. After another two years he could be promoted to Principalis, with a double salary, in charge of delivering messages (Tesserarius) or as an assistant centurion (Optio) or standard bearer (Signifer) at the corps of the century; or, if literate and numerate capable, he could join the administrative staff of the prefect.
Only a few soldiers could attain the rank of Principalis; however those that did, during the course of their service, were designated Evocati Augusti by the emperor. This designation allowed them to be promoted to technical administrative posts, or instructors in Rome, or to a century in a legion, and accordingly extend their career. Certain principalis could at the end of their career be promoted to Centurion in the Guard; this would be the peak of his career. Anyone ambitious for further promotion would need to transfer to a legion.
The Military tribunes (Tribuni Militum) at the head of the cohorts were Roman Cavalrymen. In contrast to many superior cadres of the Army, who originated from the Equestrian Order, these tribunes started their career in the ranks of the Guard and were promoted from the ranks in the hierarchy. Next after becoming Centurions, they had to serve for a period of one year as superior centurions in one or several legions before achieving the status of Primus pilus (the highest ranked Centurion in a legion). Upon return to Rome, they occupied successively the positions of Tribunes of the Vigiles, Tribune of the Urban Cohort and finally Tribune of the Guard. · 
Other leading paths towards the tribunate were possible, including service entirely made in the legions, attaining the rank of Primus pilus before departing to Rome. Nevertheless, all tribunes were combat veterans with extensive military experience. ·  Each tribune served in Rome for one year, following which, a certain number of the men would retire.
A few of them, ranking placement at the top of the hierarchy, could obtain a second term as Primus Pilus and advance towards the superior echelons of the equestrian career ·  possibly becoming the Praetorian prefect.
The majority of the prefects, however, were ordinary men of the equestrian rank by birth. The men who attained the command of the Guard following year 2 BC were equites with an elevated seniority, classifying right behind the prefect of Egypt. Starting from Vespasian, whose son, Titus was himself a Praetorian prefect, they were ranked first.
The Praetorian Guard, like all legionnaires, disposed of various equipment to execute different missions. More particularly as bodyguard, escort or reserve military force, they housed adaptable equipment for each function.
For heavy packed combat infantry lines (Triplex Acies System), they mounted helmets, armor (Lorica segmentata, Lorica hamata, Lorica squamata specially in the 2nd and 3rd centuries), heavy colorful shields (scuta), javelots (pila), and later even lances (hasta, lancea)
Praetorian Guard helmets included tall Galea with elaborate detail worked into the metal. Shields were relatively circular and more robust compared to the regular rectangular shape of legions. Each legion had its own emblem displayed on its Scutum (shield) and the Praetorian Guard were probably the only unit to include additional insignias on their shields. Each cohort had their own version of Praetorian insignias. Praetorian Guard units shouldered lion skin capes and their colours were so decorated with awards, that the men had a difficulty in carrying them on long marches.
The Praetorian Guard colours included the winged Goddess of Victory.
For escorts, the oval shields and lances replaced the scuta and pila. Missions in Rome, at the heart of the city in principal was forbidden to soldiers, they wore a toga.
The Praetorian Guard, like all legionaries, shared similar insignias, mainly on their shields. Praetorian Guard shields included wings and thunderbolts, referring to the Roman equivalent form of Jupiter and also uniquely included Scorpions, Stars and Crescents.