History Memes

Funny enough, the Emperors actually had several bodyguard units - in the city of Rome, they could theoretically call on the Imperial German Bodyguard (a genuine military unit made of foreigners - actually very loyal, because they had no local loyalties to tempt them), Urban Cohorts (riot police), and vigiles (police/firefighter combination) in addition to the Praetorian Guard. The Praetorian Guard's advantage came in that they useful as a secret police force in dealing with politicians and other such potential conspirators. The Praetorians were sometimes called the toga'd guard (cohors togata) because they spent most of their time in togas, the equivalent of a formal suit, quietly lurking around the powerful and notable and paying close attention to potential 'disloyalty'.

Most Emperors found the Praetorians indispensable for this reason - even those who didn't let the Praetorians engage in their favorite pastimes of brutality and extrajudicial murder found the espionage angle invaluable in preventing other would-be Emperors from taking the imperial position - and the former Emperor's head. The Emperor Nerva who, after gathering sufficient evidence to prove a group of Senators were conspiring against him, invited them to sit with him before the gladiator games, and displayed to them several sharpened swords, letting them take the swords and test the sharpness for themselves in his presence.

Rather than a threat, this was a kind of bravado. By acting on this knowledge before the conspiracy came to fruition, letting the Senators, subtly, know that not only did the Emperor realize full-well what they were up to, but that he wasn't afraid of whatever they might throw at him, he effectively quashed the conspiracy, and did not need to take any further action. That's the sort of thing that the Praetorian Guard, in the hands of an exceptionally restrained Emperor, gave Emperors the power to do. In ferreting out conspiracies, knowledge itself is power, and the Praetorians, skulking little shits that they were, offered knowledge that would otherwise be hidden from an Emperor.