The one great work of Sejanus has, quite undeservedly, involved his name in obloquy. He organized the Prætorian guards, and collected that portion of them who were on duty at Rome in barracks. The Prætorian guards constituted the home army of Italy; they were not only the bodyguard of the Emperor. Indeed, it seems that in the time of Augustus the Emperor’s bodyguard was a selected troop of Germans, the Swiss guards of the Pope being thus curiously anticipated by the first Emperor. The organization of the Prætorians was slightly different from that of the rest of the army; they were divided not into legions--or, as we should say, regiments--of about 6,000 men, but into cohorts (the cohort, or battalion, ordinarily consisted of 600 men, but a Prætorian cohort numbered 1,000). In other words, the home army was divided into units available by their size for garrison purposes. These men received higher pay and better allowances than the legionaries, and were, in fact, the pick of the service. Everything was done that could be done to attach them to the person of the Emperor and to distinguish them from the rest of the army. The mutinies in Pannonia and on the Rhine had indicated a weak spot in the organization of the Empire. How if the mutineers had been successful, if Germanicus had not resisted their wish to make him Emperor? They would have marched upon Rome. It was clearly necessary that Italy should be provided with a sufficient force to defend the seat of government from its own armies and to demonstrate the inevitable failure of any attempt from the Provinces to overturn the civil power. It was probably considerations of this nature which impelled Tiberius to give careful attention to the organization of the Prætorians, and he doubtless considered himself fortunate in being able to entrust this important work to a capable officer of whose fidelity he was well assured. The absence of barracks had proved a source of disorder; the Prætorians had been scattered in lodgings throughout the city and other towns. Not only was their discipline thus rendered a matter of difficulty, but their sense of corporate unity was impaired, and the language used of them inclines us to the supposition that so far from being an adequate police force, they were not infrequently themselves the source of disturbances in the streets. In order to correct these abuses, Sejanus built a large camp just outside the walls of Rome; it occupied the site of the well-known Pincian gardens. The force thus organized numbered twelve thousand men--three so-called Urban cohorts, nine Prætorian. The men were carefully chosen from the regions adjacent to the city, or from the ancient Latin colonies; care was taken to give them a specially Italian character.