The elaborate scheme for the defence of the Empire against its restless and reckless foes was brought to perfection under Diocletian and Constantine. Armies and fleets judiciously posted were always ready to repel an attack or to carry offensive operations into an enemy’s country. A chain of muniments guarded the frontiers in every locality where an assault could be feared. Forts and fortified camps sufficiently garrisoned lined every barrier, natural or artificial, at measured distances. Suitable war vessels floated on the great circumscribing waterways; and where these were deficient their place was supplied by walls of masonry, by trenches, embankments, and palisades, or even by heterogeneous obstructions formed of felled trees with their branches entangled one with the other.[681] Border lands were granted only to military occupants, who held them by a kind of feudal tenure in return for their service on the frontier.[682] Every important station was guarded by from 2,000 to 3,000 soldiers; and in the Eastern Empire the division of the army to which such duties were assigned may have amounted to over 200,000 men of all soldiers, arms,[683] etc. These forces were called the _Limitanei Milites_, or Border Soldiers, and in each province of the exterior range were under the command collectively of a Count or Duke.[684] Such were the stationary forces of the Empire, of whose services the frontiers could not be depleted should a mobile army be required to meet the exigences of strategic warfare. Large bodies of troops were, therefore, quartered in the interior of the country, which could be concentrated in any particular locality under the immediate disposition of the Masters of the Forces. This portion of the army was organized in two divisions to which were given the names of _Palatines_ and _Comitatenses_. The former, which held the first rank, were stationed in or near the capital under the two Masters[685] at head-quarters; and, in accordance with their designation, were identified most nearly with the conception of defending the Imperial Palace or heart of the state. The latter were distributed throughout the provinces under the three Masters whose military rule extended over the East, Thrace, and Illyricum respectively. The _Palatine_ troops comprised about 50,000 men, the _Comitatenses_ about 70,000.[686] Cavalry formed a large proportion of all the forces, and may be estimated at about one third of the _Limitanei_ and nearly one fourth of the other branches. In addition to these troops a fourth military class, the highest of all, was formed, the Imperial Guards already mentioned,[687] viz., the Excubitors, Protectors, Candidates, and Scholars. The latter body consisted of seven troops of cavalry, each 500 strong, 3,500 in all.[688] Owing their position solely to birth or veteran service, the three former groups were probably much less numerous, but their actual number is unknown.[689] The usual division of the infantry was the legion of 1,000 men, that of the horse the _vexillatio_ containing 500.[690] The various bodies of foot soldiers were distinguished by the particular emblems which were depicted on their brightly painted shields,[691] but amongst horse and foot alike each separate body was recognizable by an ensign of special design, for the former a _vexillum_, for the latter a dragon. The Imperial standard, or that of the general in chief command, was a purple banner embroidered with gold and of exceptional size. The _vexilla_ were dependent horizontally from a cross-bar fixed to the pole or spear by which they were elevated. Mounted lancers displayed small pennons or streamers near the points of their weapons,[692] but these were removed as an encumbrance on the eve of battle.[693] Full armour was worn, in some troops even by the horses.[694] Besides the weapons adapted for close conflict, much reliance was placed on missiles, javelins and slings, but especially bows and arrows in the hands of mounted archers.[695] In replenishing the ranks great discrimination was exercised; and not only the physical fitness of the recruit,[696] but the social atmosphere in which he had sprung up was made the subject of strict inquiry.