The main dependence of the legion was on the infantry, which wore heavy armor consisting of helmet, breastplate, greaves on the right leg, and on the left arm a buckler, four feet in length and two and a half in width. The helmet was originally made of leather or untanned skin, strengthened and adorned by bronze or gold, and surmounted by a crest which was often of horse-hair, and so made as to give an imposing look. The crests served not only for ornament, but to distinguish the different centurions. The breastplate, or cuirass, was generally made of metal, and sometimes was highly ornamented. Chain-mail was also used. The greaves were of bronze or brass, with a lining of leather or felt, and reached above the knees. The shield worn by the heavy-armed infantry was not round, like that of the early Greeks, but oval or oblong, adapted to the shape of the body, such as was adopted by Philip and Alexander, and was made of wood or wicker-work. The weapons were a light spear, a pilum, or javelin, over six feet long, terminated by a steel point, and a short cut-and-thrust sword with a double edge. Besides the armor and weapons of the legionary, he usually carried on the marches provisions for two weeks, three or four stakes used in forming the palisade of the camp, besides various tools,--altogether a burden of sixty or eighty pounds per man. The legion was drawn up eight deep, and three feet intervened between rank and file, which disposition gave great activity, and made it superior to the Macedonian phalanx, the strength of which depended on sixteen ranks of long pikes wedged together. The general period of service for the infantry was twenty years, after which the soldier received a discharge, together with a bounty in money or land.
The cavalry attached to each legion consisted of three hundred men, who originally were selected from the leading men in the State. They were mounted at the expense of the State, and formed a distinct order. The cavalry was divided into ten squadrons. To each legion was attached also a train of ten military engines of the largest size, and fifty-five of the smaller,--all of which discharged stones and darts with great effect. This train corresponded with our artillery.
The Roman legion--whether it was composed of four thousand men, as in the early ages of the republic, or six thousand, as in the time of Augustus--was divided into ten cohorts, and each cohort was composed of Hastati (raw troops), Principes (trained troops), Triarii (veterans), and Velites (light troops, or skirmishers). The soldiers of the first line, called Hastati, consisted of youths in the bloom of manhood, who were distributed into fifteen companies, or maniples. Each company contained sixty privates, two centurions, and a standard-bearer. Two thirds were heavily armed, and bore the long shield; the remainder carried only a spear and light javelins. The second line, the Principes, was composed of men in the full vigor of life, divided also into fifteen companies, all heavily armed, and distinguished by the splendor of their equipments. The third body, the Triarii, was composed of tried veterans, in fifteen companies, the least trustworthy of which were placed in the rear; these formed three lines. The Velites were light-armed troops, employed on out-post duty, and mingled with the horsemen. The Hastati were so called because they were armed with the hasta, or spear; the Principes for being placed so near to the front; the Triarii, from having been arrayed behind the first two lines as a body of reserve. The Triarii were armed with the pilum, thicker and stronger than the Grecian lance, four and a half feet long, of wood, with a barbed head of iron,--so that the whole length of the weapon was six feet nine inches. It was used either to throw or thrust with, and when it pierced the enemy's shield the iron head was bent, and the spear, owing to the twist in the iron, still held to the shield. Each soldier carried two of these weapons, and threw the heavy pilum over the heads of their comrades in front, in order to break the enemy's line. In the time of the empire, when the legion was modified, the infantry wore cuirasses and helmets, and carried a sword and dagger. The select infantry were armed with a long spear and a shield; the rest, with a pilum. Each man carried a saw, a basket, a mattock, a hatchet, a leather strap, a hook, a chain, and provisions for three days. The Equites (cavalry) wore helmets and cuirasses, like the infantry, having a broadsword at the right side, and in the hand a long pole. A buckler swung at the horse's flank. They were also furnished with a quiver containing three or four javelins.
The artillery were used both for hurling missiles in battle, and for the attack on fortresses. The tormentum, which was an elastic instrument, discharged stones and darts, and was held in general use until the discovery of gunpowder. In besieging a city, the ram was employed for destroying the lower part of a wall, and the balista, which discharged stones, was used to overthrow the battlements. The balista would project a stone weighing from fifty to three hundred pounds. The aries, or battering-ram, consisted of a large beam made of the trunk of a tree, frequently one hundred feet in length, to one end of which was fastened a mace of iron or bronze resembling in form the head of a ram; it was often suspended by ropes from a beam fixed transversely over it, so that the soldiers were relieved from supporting its weight, and were able to give it a rapid and forcible swinging motion backward and forward. When this machine was further perfected by rigging it upon wheels, and constructing over it a roof, so as to form a testudo, which protected the besieging party from the assaults of the besieged, there was no tower so strong, no wall so thick, as to resist a long-continued attack, the great length of the beam enabling the soldiers to work across the defensive ditch, and as many as one hundred men being often employed upon it. The Romans learned from the Greeks the art of building this formidable engine, which was used with great effect by Alexander, but with still greater by Titus in the siege of Jerusalem; it was first used by the Romans in the siege of Syracuse. The vinea was a sort of roof under which the soldiers protected themselves when they undermined walls. The helepolis, also used in the attack on cities, was a square tower furnished with all the means of assault. This also was a Greek invention; and the one used by Demetrius at the siege of Rhodes, B. C. 306, was one hundred and thirty-five feet high and sixty-eight wide, divided into nine stories. The turris, a tower of the same class, was used both by Greeks and Romans, and even by Asiatics. Mithridates used one at the siege of Cyzicus one hundred and fifty feet in height. These most formidable engines were generally made of beams of wood covered on three sides with iron and sometimes with rawhides. They were higher than the walls and all the other fortifications of a besieged place, and divided into stories pierced with windows; in and upon them were stationed archers and slingers, and in the lower story was a battering-ram. The soldiers in the turris were also provided with scaling-ladders, sometimes on wheels; so that when the top of the wall was cleared by means of the turris, it might be scaled by means of the ladders. It was impossible to resist these powerful engines except by burning them, or by undermining the ground upon which they stood, or by overturning them with stones or iron-shod beams hung from a mast on the wall, or by increasing the height of the wall, or by erecting temporary towers on the wall beside them.
Thus there was no ancient fortification capable of withstanding a long siege when the besieged city was short of defenders or provisions. With forces equal between the combatants an attack was generally a failure, for the defenders had always a great advantage; but when the number of defenders was reduced, or when famine pressed, the skill and courage of the assailants would ultimately triumph. Some ancient cities made a most obstinate resistance, like Tarentum; like Carthage, which stood a siege of four years; like Numantia in Spain, and like Jerusalem. When cities were of immense size, population, and resources, like Rome when besieged by Alaric, it was easier to take them by cutting off all ingress and egress, so as to produce famine. Tyre was taken by Alexander only by cutting off the harbor. Cyrus could not have taken Babylon by assault, since the walls were of such enormous height, and the ditch was too wide for the use of battering-rams; he resorted to an expedient of which the blinded inhabitants of that doomed city never dreamed, which rendered their impregnable fortifications useless. Nor probably would the Romans have prevailed against Jerusalem had not famine decimated and weakened its defenders. Fortified cities, though scarcely ever impregnable, were yet more in use in ancient than modern times, and greatly delayed the operations of advancing armies; and it was probably the fortified camp of the Romans, which protected an army against surprises and other misfortunes, that gave such permanent efficacy to the legions.
The chief officers of the legion were the Tribunes; and originally there was one in each legion from the three tribes,--the Ramnes, Luceres, and Tities. In the time of Polybius the number in each legion was six. Their authority extended equally over the whole legion; but to prevent confusion, it was the custom for them to divide into three sections of two, and each pair undertook the routine duties for two months out of six; they nominated the centurions, and assigned each to the company to which he belonged. These tribunes at first were chosen the commanders-in-chief, by the kings and consuls; but during the palmy days of the republic, when the patrician power was pre-eminent, they were elected by the people, that is, the citizens. Later they were named, half by the Senate and half by the consuls. No one was eligible to this great office who had not served ten years in the infantry or five in the cavalry. The tribunes were distinguished by their dress from the common soldier. Next in rank to the tribunes, who corresponded to the rank of brigadiers and colonels in our times, were the Centurions, of whom there were sixty in each legion,--men who were more remarkable for calmness and sagacity than for courage and daring valor; men who would keep their posts at all hazards. It was their duty to drill the soldiers, to inspect arms, clothing, and food, to visit the sentinels and regulate the conduct of the men. They had the power of inflicting corporal punishment. They were chosen for merit solely, until the later ages of the empire, when their posts were bought, as is the case to some extent to-day in the English army. The centurions were of unequal rank,--those of the Triarii before those of the Principes, and those of the Principes before those of the Hastati. The first centurion of the first maniple of the Triarii stood next in rank to the tribunes, and had a seat in the military councils. His office was very lucrative. To his charge was intrusted the eagle of the legion. As the centurion might rise from the ranks by regular gradation through the different maniples of the Hastati, Principes, and Triarii, there was great inducement held out to the soldiers. It would, however, appear that the centurion received only twice the pay of the ordinary legionary. There was not therefore so much difference in rank between a private and a captain as there is in our day. There were no aristocratic distinctions in the ancient world so marked as those existing in the modern. In the Roman legion there was nevertheless a regular gradation of rank, although there were but few distinct offices. The gradation was determined not by length of service, but for merit alone, of which the tribunes were the sole judges; hence the tribune in a Roman legion had more power than that of a modern colonel. As the tribunes named the centurions, so the centurions appointed their lieutenants, who were called sub-centurions. Still below these were two sub-officers, or sergeants, and the decanus, or corporal, to every ten men.
There was a change in the constitution and disposition of the legion after the time of Marius, until the fall of the republic. The legions were thrown open to men of all grades; they were all armed and equipped alike; the lines were reduced to two, with a space between every two cohorts, of which there were five in each line; the young soldiers were placed in the rear; the distinction between Hastati, Principes, and Triarii ceased; the Velites disappeared, their work being done by the foreign mercenaries; the cavalry ceased to be part of the legion, and became a distinct body; and the military was completely severed from the rest of the State. Formerly no one could aspire to office who had not completed ten years of military service, but in the time of Cicero a man could pass through all the great dignities of the State with a very limited experience of military life. Cicero himself did military service in but one campaign.
Under the emperors there were still other changes. The regular army consisted of legions and supplementa,--the latter being subdivided into the imperial guards and the auxiliary troops.
The Auxiliaries (Socii) consisted of troops from the States in alliance with Rome, or those compelled to furnish subsidies. The infantry of the allies was generally more numerous than that of the Romans, while the cavalry was three times as numerous. All the auxiliaries were paid by the State; their infantry received the same pay as the Roman infantry, but their cavalry received only two thirds of what was paid to the Roman cavalry. The common foot-soldier received in the time of Polybius three and a half asses a day, equal to about three cents; the horseman three times as much. The praetorian cohorts received twice as much as the legionaries. Julius Caesar allowed about six asses a day as the pay of the legionary, and under Augustus the daily pay was raised to ten asses,--little more than eight cents per day. Domitian raised the stipend still higher. The soldier, however, was fed and clothed by the government.
The Praetorian Cohort was a select body of troops instituted by Augustus to protect his person, and consisted of ten cohorts, each of one thousand men, chosen from Italy. This number was increased by Vitellius to sixteen thousand, and they were assembled by Tiberius in a permanent camp, which was strongly fortified. They had peculiar privileges, and when they had served sixteen years received twenty thousand sesterces, or more than one hundred pounds sterling. Each praetorian had the rank of a centurion in the regular army. Like the body-guard of Louis XIV. they were all gentlemen, and formed gradually a great power, like the Janissaries at Constantinople, and frequently disposed of the purple itself.