SPECIAL HISTORY AND ORIGINS OF PRAETORIAN GUARD
By AD 69, the Praetorian Guard had been in operation for nearly a century. Established by Augustus in 27 BC, it was not a new formation. Commanders in the late Republic had made use of similar units for protection, with the first specific reference to a Praetorian cohort (cohors praetoria) appearing in Sallust’s account of the war against Catiline in 62 BC (Catiline 60.5). We also hear of provincial governors having a Praetorian cohort on staff for administrative duties, as in Cicero’s speeches against Verres.
Augustus cleverly adapted these two different types of Praetorian cohort for his own purposes. It was clear, given his route to power, that he needed a unit that would ensure protection for him and for the imperial family. The Praetorian Guard thus became the personal army of the emperor.
The guard at work
The exact number of men comprising the Praetorian Guard is debated. We know that Augustus established nine cohorts (Tacitus, 4.5.3) and epigraphic evidence reveals that Tiberius increased that number to twelve. But scholars are divided as to whether these cohorts numbered 500 or 1000 men. The ancient sources only mention the latter number (Dio, 55.24.6; Tacitus, 2.93.2) and it is clear from the archaeological remains of the camp established by Tiberius in AD 23 that 4.2.1). But the construction of such a sizeable fortress on the Viminal Hill overlooking the city more importantly provided a clear message that the Praetorian Guard had become a permanent fixture of the Principate.
