The Roman army, made up of the Praetorian Guard, legions, auxiliary forces and navy, did not exist as a permanent organization under a centralized command. During the Republic, legions were raised from the citizenry when required and placed under the command of a senator of consular rank who was temporarily awarded the power of imperium (military command), which he could only hold outside Italy, unless exceptional circumstances necessitated otherwise. This legalized but limited his control of a military force. It also facilitated the development of loyalty to the person of that general (imperator); in the first century BC this became a particularly dangerous facet of the Roman world. During this age of the imperatores, some of these generals saw an opportunity to use their armies for personal glory and advancement. The origins of the Praetorian Guard lay in the bodyguard units men such as Antony and Octavian created to amplify their status.
Part of displaying military prestige for an imperator involved having a body of selected soldiers to act as his personal bodyguard. These soldiers, the ‘praetorians’, were named after the term for a general’s tent or residence on campaign, the praetorium. The word was derived from the word praetor, which meant literally ‘the man who goes before others’. In a general sense the word meant ‘leader’ or ‘chief’ and was applied to a specific level of senatorial magistracy, the praetorship, with certain duties. A propraetor was a man who had served as a praetor and could be sent to govern a province. Praetorium could then be literally translated as ‘the place of the man who goes before others’. His bodyguard soldiers were organized into cohorts (cohortes), a standard Roman military term for a body of around 480 men and normally applied to subdivisions of legions. The word also means ‘courtyard’ or ‘enclosure’, and the military application therefore derives from this by meaning literally ‘a courtyard’s-worth of men’.
The Praetorian Guard also served as a vital bulwark for the emperor against the power and influence of the senate. The Guard’s mere existence was a constant reminder to the senate of the emperor’s ability to use force to assert his position. As Gibbon so memorably observed, the praetorians represented ‘the emperor’s power and status and gave him the ability to coerce the Roman aristocracy’. It was a precarious balance. The emperor was dependent on a force that he needed to have absolute authority over. The proximity of the Praetorian Guard to the emperor, both in a metaphorical and physical sense, meant that the emperor’s prestige and influence had always to be greater than that of the praetorians if he was to maintain control.
It was the idea of men who would protect their general in a military context that Octavian as Augustus would later turn into a permanent institution as part of the greater Roman army (also made permanent under his rule). It was also the component of the army that enjoyed special status by virtue of being closest to him as emperor. By being continuously stationed in Rome from the reign of Tiberius on, the Praetorian Guard became the most visible embodiment both of the emperor’s power and of the change in government since the Republic. It is hardly surprising then that the overwhelming popular impression of the Roman Empire is of a highly militarized society. The ubiquitous nature of the Roman army and its dominance of so much of the record have reinforced this.
As a new institution the Praetorian Guard and its command had to be incorporated into the Roman hierarchy and positioned in a way that maximized prestige while minimizing the risk to the emperor. The wealthiest and most powerful members of Roman society were the senatorial families. Their male members served in a number of prestigious magistracies, proceeding along a fairly standardized career path that climaxed with service as one of the praetors, and then as one of the two consuls serving at any one time. Senators who had served as praetors were eligible to be appointed to command legions or govern provinces. Giving command of the Guard to a senator would have been far too risky. The position of ‘emperor’ as we understand it did not officially exist. Augustus held certain Republican senatorial offices but his real power was vested in his special personal authority and prestige. This involved considerable guile and tact because of the technical equality between him and other senators, any one of whom might challenge his power. A senator with command of the Praetorian Guard might have that potential.
Augustus therefore used for command of the Guard men of equestrian rank, a more numerous body of second-grade aristocrats whose property qualification for eligibility was much lower. These men could serve as procurators, the financial administrators of provinces, as well as in a host of other positions. These ranged from minor procuratorial posts or the prefecture of an auxiliary military unit such as a cavalry wing right up, under the Empire, to commanding the Praetorian Guard, governing Egypt, controlling the grain supply or serving as prefect of Rome. All these latter prefectures were of such importance that an emperor could not afford to give them to senators who might then emerge as his rivals. Equestrians were a far less risky prospect because they lacked the rank equivalence a senator enjoyed with the emperor. The whole system relied on a complex web of patronage, loyalties, interest groups and factions trickling down from the emperor from the time of Augustus on.
The Roman world by the time of Augustus was not only enormous by the standards of the ancient world, but also by our own. It already stretched from Gaul (modern France) to Syria and Egypt in the east and included much of western, central and southern Europe as well as North Africa and Turkey. New conquests ensured its expansion until the reign of Trajan (98–117). The Roman army was widely distributed throughout these territories, with the largest garrisons in key and frontier provinces such as Syria and along the Rhine. Larger and more complex than any other western ancient civilization, the Roman world challenged the logistical and administrative powers of what was still a relatively primitive era. In this context all Roman soldiers, not just the praetorians, were the everyday manifestation of the state. Soldiers took on all sorts of minor administrative and supervisory duties. These ranged from acting as police (an especially vital role that involved centurions bringing ‘the power of the central administration to the level of the villages’), overseeing amongst many other duties construction projects, raising taxes, to operating the mint and supervising the movement of grain. Roman soldiers, including veterans, were thus the principal means through which the state acted and enforced its measures.
Not surprisingly, Roman soldiers, especially the Praetorian Guard, were sometimes depicted in the popular culture of the time as privileged bullies who enjoyed a favoured status above the law. Juvenal’s incomplete Sixteenth Satire itemizes the various advantages the military benefited from, such as the freedom to thrash a civilian without fear of redress and the knowledge that a soldier pursuing a court case could be sure to have it heard immediately, unlike everyone else. Juvenal was probably writing about the way praetorians, the most privileged of all Roman soldiers, behaved. The state that depended so much on military cooperation and support could not afford to have a disaffected army.
Today the Rome Metro’s Linea B includes a stop called Castro Pretorio. Visitors emerge from there on to the extremely busy Viale Castro Pretorio. A short walk leads to the well-preserved original north and east walls of the Castra Praetoria, the Guard’s fort and headquarters. Created by the praetorian prefect Lucius Aelius Sejanus in or around 23 during the reign of Tiberius (14–37), the fort based the whole Guard on the outskirts of Rome where it remained until its disbandment in 312. The location, in the north-eastern part of the settled area, was thinly populated and had hitherto mainly been used for burials. It was a tactful setting which conveniently obfuscated the fact that the emperors’ power was ultimately vested in their ability to harness military force. Nevertheless, it was close enough to Rome for the praetorians to be on hand in the centre of the city in minutes, reinforcing their fellows in the cohorts serving at any given moment as the emperor’s guard. This much is apparent from some of the dynamic episodes when praetorians proved themselves to be the most decisive force in Rome.
The decision to relocate the whole Guard to Rome in AD 23 was one of the most significant moments in the history of the Guard and the Roman world. It was a logical progression from Augustus’ decision to make the Guard a permanent institution, itself a revolutionary move, and place it under commanders appointed by him. Now that it was based in Rome the Guard could influence political events directly. The only obstacles in its way were emperors with the power and prestige to control the Guard and harness its power. The moment an emperor fell short of what was expected of him, it was all too often the praetorians who determined what happened next.
The Praetorian Guard, whether in its barracks, performing any one of a multiplicity of practical duties or being with the emperor on campaign, was fundamental to the exercise and retention of imperial power. The challenge for any emperor was to keep the Guard and its prefects under control. As Gibbon pointed out, that was extremely difficult to do. The Roman Empire has always had much to teach us about the consequences and dangers of absolute power in a state where so much could depend on the abilities and circumstances of a single person. The Praetorian Guard was one of the most potent ingredients in the story of the Roman emperors.