LEGION, in the Roman military system, corresponded in force and organization to what in modern times we should call a corps d'armee. It differed in constitution at dif ferent periods of I taman history. In the time of the republic, a legion comprised 4,500 men. thus divided: 1200 hastati, or inexperienced troops; 1200 priacipes, or well-tra.ined soldiers; 1200 relites, or skirmishers; 600 triarii, or pilani, veterans forming a reserve; and 800 &Julies, knights who acted as cavalry, and belonged to families of rank. During this period the legions were formed only for the season,. standing armies being of later growth.
The hastati, principes, and triarii formed three separate lines, each into 10 maniples or companies, of 120 men each in the case of the two front lines, and of 60 men in the triarii. A maniple was commanded by in eeDturion or captain, who had a second centurion, or lieut., and two sub-officers, or sergeants, under him: as non-commissioned officers, there was a decanus, or corporal, to every squad or tent of 10 men. The senior centurion of each line commanded that line, and had therefore functions corresponding to a modern lieut.col. The primipau, or senior centurion of the triarii, was the most important regimental officer, and commanded the legion in the absence of the tribunes. The 300 cavalry formed a regiment of 10 ton ice, or troops of 30 horsemen, each tinder 3 decurians, of whom the senior had the command. The velites were light troops, not form part of the line of battle; had apparently no officers of their own; and were attached to the 30 maniples in equal proportions. The staff of the legion consisted of 6 tribunes, who managed the paying, quartering, provisioning, etc., of the troops, and who com manded the legion in turns for a period mach of 2 months. This changing command, although inconvenient, lasted till the times of the civil wars, when a legatos, or lieut.gen.,
was appointed as permanent commandant of tire legion.
The offensive weapons of the hastati and principes were two barbed iron-headed javelins, one of which was hurled at the enemy on the first onslaught, while the other was retained as a defense against cavalry. The triarii had long pi'kcs. In addition to these arms, every soldier bore a short, strong, cut-and-thrust, two-edged The legionaries' defensive armor consisted of plumed helmet, breast-plate, iron-bound boot for the right leg, and a semi-cylindrical shield 4 ft. long by 2i broad, The velites had no defensive armor, were. lightly armed, and in action usually operated for flanking, poses. Each maniple bore an ensign aloft., and each legion had its distinguishing eagle. Up to the time of Marius, service in a legion was sought as honorable occupation, arid men of some means were alone eligible; but Marius enlisted slaves, and turned the legions into corps of a purely mercenary army. At the same period, the manipular forma tion was abolished, the 3 lines were assimilated, and the legion was divided into 10 cohorts, each of 3 maniples. Soon the cohorts were raised to 600 men, making the legion 6,000 infantry besides cavalry and velites. It was ranged in 2 lines of 5 cohorts each; but Cesar altered the formation to 3 lines, of respectively 4, 3, and 3 cohorts.
During the later empire, the legion became complex and unmanageable; many sorts of arms being thrown together, and holism catapults, and onagers added by way of artillery. having so degenerated from its pristine. simplicity and completeness, the legionary formation was soon overthrown amid the incursions of the victorious bar barians.