Peace was now established throughout the empire, and afforded Henry an opportunity for turning his attention to the introduction of measures, in the interior economy of the State, calculated to obviate for the future the dangers that had hitherto threatened it from without. The best expedient against the irruptions of the Hungarians appeared to him to be the circumvallation of the most important districts, the erection of forts and of fortified cities. The most important point, however, was to place the garrisons immediately under him as citizens of the State, commanded by his immediate officers, instead of their being indirectly governed by the feudal aristocracy and by the clergy. As these garrisons were intended not only for the protection of the walls, but also for open warfare, he had them trained to fight in rank and file, and formed them into a body of infantry, whose solid masses were calculated to withstand the furious onset of the Hungarian horse. These garrisons were solely composed of the ancient freemen, and the whole measure was, in fact, merely a reform of the ancient _arrier-ban_, which no longer sufficed for the protection of the State, and whose deficiency had long been supplied by the addition of vassals under the command of their temporal or spiritual lieges, and by the mercenaries or bodyguards of the emperors. The ancient class of freemen, who originally composed the arrier-ban, had been gradually converted into feudal vassals; but they were at that time still so numerous as to enable Henry to give them a completely new military organization, which at once secured to them their freedom, hitherto endangered by the preponderating power of the feudal aristocracy, and rendered them a powerful support to the throne. By collecting them into the cities, he afforded them a secure retreat against the attempts of the grafs, dukes, abbots, and bishops, and created for himself a body of trusty friends, of whom it would naturally be expected that they would ever side with the Emperor against the nobility. This new regulation appears to have been founded on the ancient mode of division. At first, out of every nine freemen--which recalls the _decania_--one only was placed within the new fortress, and the remaining eight were bound--perhaps on account of their ancient association into corporations or guilds--to nourish and support him; but the remaining freemen, in the neighborhood of the new cities, appear to have been also gradually collected within their walls, and to have committed the cultivation of their lands in the vicinity to their bondmen. However that may be, the ancient class of freemen completely disappeared as the cities increased in importance, and it was only among the wild mountains, where no cities sprang up, that the _centen_ or cantons and whole districts or _gauen_ of free peasantry were to be met with.