The third, and perhaps the most important, part of the barrier line consisted of the structures that were formed for the accommodation of the soldiery, and for the ready transmission of troops and stores. Neither stone walls, nor ditches, nor earthen ramparts, would alone have proved material impediments to the incursions of the Caledonians— An iron race, ... Foes to the gentler genius of the plain. It is reported that Agesilaus, when asked where were the walls of Sparta, pointed to his soldiers and said, ‘There.’ The Romans placed their chief reliance on the valour and discipline of their armies, though they did not despise the assistance of mural lines. In a foreign country, to which it was difficult to transmit relays of troops, it became a matter of great importance to economize the lives of the soldiery. Hence arose the Wall. Those portions of the great barrier which yet await our consideration, are the STATIONS, the MILE-CASTLES, the TURRETS, and the ROADS. [Sidenote: THE STATIONS.] At distances along the line which average nearly four miles, STATIONARY CAMPS (_stationes_ or _castra stativa_) were erected. These received their distinctive appellation, in contradistinction from those temporary ramparts, which were thrown up when an army halted for a night or for some brief period. The stations on the line of the Wall were military cities, adapted for the residence of the chief who commanded the district, and providing secure lodgment for the powerful body of soldiery he had under him. Here the commandant held his court; hence issued decrees which none might gainsay; here Roman arts, and literature, and luxury, struggled for existence, when all around was ignorance and barbarity. Some of the stations, though connected with the Wall, have evidently, as will afterwards be shewn, been built before it: this does not prove that they did not form part of the great design. To secure a safe retreat for the soldiers employed upon the work would necessarily be the first care of the builder. The stations are uniformly quadrangular in their shape, though somewhat rounded at the corners, and contain an area of from three to five acres. A stone wall, five feet thick, encloses them, and has probably in every instance been strengthened by a fosse, and one or more earthen ramparts. They usually stand upon ground which slopes to the south, and are naturally defended upon one side at least. [Sidenote: THE PLACE OF THE STATIONS.]