When Augustus found the world at his feet he also found himself with armies which were very expensive and somewhat ready to mutiny against him. Very promptly, therefore, he reduced his 45 legions to only about 18. This number proved too few, and by the end of his reign they had risen to 25; these in turn have been gradually increased to 30; and this will be the ordinary number for a good while longer.[162] The legionaries are the regular troops of the line, on whose disciplined fighting the safety of civilization may well depend. There are, however, no ordinary legionaries stationed in Rome, although we can, of course, obtain full information in the capital about them. Their place is taken by a magnificent and arrogant guard-corps--the Prætorians. =264. The Prætorian Guard of the Emperors.=--The Prætorian guards are the successors of the old _Prætoriani_, picked men, who guarded the Prætorium (general’s residence or tent) in the armies of the old Republic. But the new Imperators were entitled to a much larger and more permanent guard, and they also desired to have a reliable body of troops always in or near Rome to protect against an uprising. Augustus, therefore, organized nine “prætorian cohorts,” although keeping only three directly in Rome; his successor, Tiberius, however, boldly concentrated them all in the imperial city, and built for them an enormous camp behind the Viminal hill, on the northeast side of the metropolis. [Illustration: PRÆTORIAN GUARDSMEN.] Here they have remained as the dreaded engine of the Caesars. Disguise the fact as he may, every senator knows in his heart: “If the Senate defies the Emperor, the Prætorians can and will sack the Curia.” So long as the Prætorians are obedient no Emperor need tremble overmuch at stories of a provincial uprising. When the Prætorians desert he had better, as did Nero, slink away to commit suicide. The guard-corps is jealously regarded by the frontier legions who sometimes turn against it, but thanks to its position at the capital its power is tremendous. Even the privates walk down the streets with a confident swagger--can they not make and unmake Emperors? If the army really controls the Empire, the Prætorians go far to control the will of the army. =265. The Prætorian Præfect and the Prætorian Camp.=--Such being the case, there is one high official whom the Cæsars will always select with greater care than any other--the _Prætorian Præfect_. On this general rests responsibility for the military efficiency and loyalty of the corps. If he is a scheming bloody man, he can, like Tiberius’s præfect Sejanus, almost place himself upon the throne; and if he is simply a faithful competent officer, his public services excel that of any civil functionary.