For the video game, see Praetorians (game)
This article is part of the series on:
Military of ancient Rome (Portal) 800 BC–AD 476
The Praetorian Guard (in Latin: praetoriani) consisted of a special force of bodyguards used by Roman Emperors. Before being used by the emperors, a Roman general's bodyguard, also styled the praetorian guard, was employed, dating at least to the Scipio family — around 275 BC. Constantine I dissolved it in the 4th century.

Early Guard
Following the death of Sejanus, who was sacrificed for the Donativum (imperial gift) promised by Tiberius, the Guards began to play an increasingly ambitious and bloody game in the Empire. With the right amount of money, 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. The Praetorians placed Claudius on the throne, daring the Senate to oppose their decision.
During 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 to 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 one 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 kill off emperors, it had no 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 Praetorians and started a new formation from his own Pannonian Legions. Unruly mobs in Rome fought often 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. The Palmyrans were easily defeated. This led to the orthodox view that Diocletian and his colleagues evolved the sacer comitatus (the field escort of the emperors), which included field units that utilized a selection process and command structure modeled after the old Praetorian cohorts, but was not of uniform composition and was much larger than a Praetorian cohort.

Political role
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 Jovians and Herculians (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. By the time Diocletian retired on May 1, 305, their Castra Praetoria seems to have housed only a minor garrison of Rome.
The final act of the Praetorians in imperial history started in 306, when Maxentius, son of the retired emperor Maximian, was passed over as a successor: the troops took matters into their own hands and elevated him to the position of emperor in Italy on October 28. Caesar Flavius Valerius Severus, following the orders of Galerius, attempted to disband the Guard but only managed to lead the rest of them in revolting and joining Maxentius. When Constantine the Great, launching an invasion of Italy in 312, forced a final confrontation at the Milvian Bridge, the Praetorian cohorts made up most of Maxentius' army. Later in Rome, the victorious Constantine definitively disbanded the Praetorian Guard. The soldiers were sent out to various corners of the Empire, and the Castra Praetoria was demolished. For over 300 years they had served, and the destruction of their fortress was a grand gesture, inaugurating a new age of imperial history and ending that of the Praetorians.

Guard's twilight years
Although its name has become synonymous with intrigue, conspiracy, disloyalty and assassination, it could be argued that for the first two centuries of its existence the Praetorian Guard was, on the whole, a positive force in the Roman state. During this time it mostly removed (or allowed the removal of) cruel, weak, and unpopular emperors while generally supporting just, strong, and popular ones. By protecting these monarchs, thus extending their reigns, and also by keeping the disorders of the mobs of Rome and the intrigues of the Senate in line, the Guard helped give the empire a much needed stability that led to the period known as the Pax Romana.
Only after the reign of Marcus Aurelius, when this period is generally considered to have ended, the guard began to deteriorate into the ruthless, mercenary and meddling force for which it has become infamous. However, during the Severan dynasty and afterwards during the Crisis of the Third Century, the legions, the Senate and the emperorship along with the rest of Roman government were falling into decadence as well.

Legacy of the Guard

Relationships between emperors and their Guard
Although the Praetorians have similarities, they are unlike any of the regular Legions of the Roman Empire. Their nine cohorts (one less than a legion) were larger, the pay and benefits were better, and its military abilities were reliable. They also received gifts of money called Donativum from the emperors. As conceived by Augustus, the Praetorian cohorts totaled around 9,000 men, recruited from the legions of the regular army or drawn from the most deserving youths in Etruria, Umbria, and Latium (three provinces in central Italy). Over time the pool of recruits expanded to Macedonia, Hispania Baetica, Hispania Tarraconensis, Lusitania and Illyricum. Vitellius formed a new Guard out of the Germanic legions, while Septimus Severus did the same with the Pannonian legions. He also chose replacements for the units' ranks from throughout the Roman Empire.
Around the time of Augustus (c. 5) each cohort of the Praetorians numbered 1,000 men, increasing to a high-water mark of 1,500 men. As with the normal legions, the body of troops actually ready for service was much smaller. Tacitus reports that the number of cohorts was increased to twelve from nine in 47. In 69 it was briefly increased to sixteen cohorts by Vitellius, but Vespasian quickly reduced it again to nine. 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 legionnaires received 225 denarii, the guards received 375 per annum. Domitian and Septimius Severus increased the stipendum (payment) to 1,500 denarii per year, distributed in January, May and September. Organization and conditions of service
From its beginnings, the guard usually included a small cavalry detachment, equites singulares augusti, to escort the emperors to important state functions and on military campaigns. It was comprised chiefly of selected, highly trusted provincials, who wore their native dress and carried their own weapons. Trajan expanded this force, opening it up to citizens and made it a permanent part of the Praetorian establishment. Its size was that of an ala quingenaria or about 512 horsemen in 16 turmae (troops). It was commanded by a Tribune, and so was, in effect a 10th Praetorian cohort. Later, Severus would double its size to an ala milliaria, giving it the same strength as the other nine cohorts.[1]

Imperial Horseguard
See the article Praetorian prefect, which also lists the incumbents of the post of Praefectus praetorio and covers the essentially civilian second life of the office, since ca 300, as administrator of a quarter of the empire), and its Germanic continuation

Prefect(s) in command of the Praetorian Guard Modern analogous uses of the term