Ancient History & Civilisation

The 'Polybian' Legion

Polybius wrote his detailed description of the Roman army’s organization in the mid-2nd century BC, although it is positioned within his work to accompany his account of the Second Punic War. The Greek historian seems to have believed, almost certainly correctly, that few significant changes had occurred in the army’s basic structure since the early 3rd century вс.

The Roman army remained a temporary militia, and the census recorded those citizens with sufficient property to make them eligible to serve. To share the burden of military service, no man was obliged to serve for more than 16 campaigns or years. Each year the Senate - the senior council of the Republic - decided how many soldiers to raise and where they would be sent. Armies were commanded by elected magistrates who held power (imperium) for 12 months, although the Senate could choose to extend this. The two consuls elected each year were the senior magistrates and given the most important military tasks. Smaller-scale operations could be entrusted to praetors, the next magisterial college in seniority to the consuls. The number of praetors rose from one per year to six during the course of the Punic Wars. When Rome was a small community it had usually sent all its men to fight a single conflict, but the growth of the state and the increasing number of military problems required the division of military effort. Legion (Latin legio) had originally meant ‘levy’ and referred to the entire Roman people under arms, but by at least the 4th century вс it had come to mean the most significant unit of the army. In Polybius’ day it was normal for a consul to be given an army of two legions, whilst praetors more often led only one.

(Above) The deployment of the manipular legion in battle The formation of the maniples was very flexible, far more so Hum the solid phalanx favoured by Hellenistic armies. It allowed the Romans to move across uneven terrain without falling into serious disorder and also permitted readier reaction to a developing crisis during a battle

The standard legion consisted of 4,200 infantrymen and 300 cavalrymen. As before, the wealthiest men formed the cavalry (equites) and were divided into 10 troops (turmae) commanded by three decuri- ons or ‘leaders of 10’. The nucleus of the cavalry remained the 18 equestrian centuries - the centuries consisting of the wealthiest citizens - all of whom were entitled to have the cost of their horse refunded by the state should it be killed in battle, but by this period large numbers of other wealthy men voluntarily served in this way. Polybius tells us that that the equites had long since adopted Hel- lenistic-style equipment, but, assuming that his audience was familiar with this, does not bother to describe it. However, we can deduce that Roman cavalrymen fought in close order, were armed with a spear and sword and protected by helmet, cuirass and circular shield.

The infantry of the legion were allocated to their roles according not just to their property, but also their age. The poorest citizens, who still owned enough to make them eligible for service, unlike the capite censi, acted as light infantry (velites), as did men too young to fight in the main battle line. The velites were equipped with a bundle of light javelins, a sword (at least from the early 2nd century BC and probably before) and a round shield. Some at least wore helmets, and all were supposed to wear pieces of animal skin, especially wolf skins, attached to these or their caps. Polybius tells us that this was intended to allow their officers to identify them in battle and reward or punish their behaviour accordingly, but it may originally have had some totemic significance. Usually there were 1,200 velites in each legion, but we do not know how they were organized or commanded in any detail.

The main strength of the legion lay in its close- order infantrymen, who were formed into three distinct lines. The first (hastati), nearest to the enemy, were formed from the younger men - probably in their late teens or early 20s. Behind them were the principes, men in their later 20s or early 30s, a time considered to be the prime of life. In the rear were the triarii, recruited from the oldest and most experienced soldiers. There were normally 1,200 each of the hastati and principes, but only 600 triarii. Each line was divided into 10 maniples and these were the basic tactical unit. However, for administrative purposes the maniple was divided into two centuries each commanded by a centurion, supported by a second-in-command (optio), standard-bearer (signifer), and guard commander (tesserarius). The centurion of the right-hand century was appointed to his command and was the senior of the two, taking charge when both were present. He then chose the man to serve as the centurion for the left-hand century. Polybius tells us that centurions were chosen to be especially steady and determined leaders, men who would stay with their troops and not charge off on their own. The legion itself did not have a single commanding officer. Instead there were six military tribunes, and command rotated between pairs of these officers.

The legion did not need to number precisely 4,200 foot and 300 horse to function properly. Sickness and casualties inevitably eroded a unit’s strength on campaign. The Senate might also decide to form especially strong legions if they felt that the military situation demanded it, and we hear of legions with between 5,000 and 6,000 men being raised at times of particular crisis. Both the equites and the triarii were recruited from a limited pool, so when larger legions were formed the extra men were divided equally amongst the hastati, principes and velites. In the field each legion was also supported by a similarly sized contingent of allied soldiers, known as an ala or ‘wing’, recruited primarily from the Latin peoples. An ala normally had as many infantry as a legion but three times the number of cavalry. It was subdivided into cohorts, but it is unclear to what extent these were tactical units, how many there were to each ala and whether they were of a fixed size. This may simply have been a vague term meaning contingent which referred to all the troops provided by a single Latin colony. Allied cohorts are recorded numbering 400-600 men and their size may have varied with the size of the ala. The ala was commanded by three prefects (praefecti sociorum) who were invariably Roman citizens. In battle the legions formed the centre of the army whilst the alae were formed on their flanks. In a consular army of two legions and two alae the latter were known as ‘Left’ and ‘Right’ respectively. The pick of the allies were separated from the alae to form the extraordinarii, a force of cavalry and infantry at the immediate disposal of the consul.

In this period none of the army officers were professional soldiers. The magistrates commanding the armies and the tribunes were elected, and the other officers appointed, and neither experience nor ability were necessarily of primary importance in their selection.


The pilum: Polybius tells us that each hastatus and princeps carried two heavy javelins, one heavier than the other. These were the famous pita which remained in the arsenal of the legions for over five centuries. A pilum consisted of a wooden shaft, some 4 ft (1.2 m) or so in length, joined to a thin iron shank, perhaps 2 ft (60 cm) long, and topped by a small pyramid-shaped point. A pilum was heavy’, and all of its weight when thrown was concentrated behind its small head, giving it tremendous penetrative power. When it punched through an enemy’s shield, the long, thin shank slid readily through the hole and had the reach to strike the man’s body. Even when the man avoided a serious wound, the pilum was difficult to dislodge and weighed down his shield. Modern tests of reconstructed pila have suggested that they had a maximum range of about 100 ft (30 m), with an effective range of perhaps half that. These tests also confirmed its great penetrative power.

A scene from the 1st-century BC altar of Gnaeus Domitius Ahenobarbus showing two legionaries in the typical uniform of the last 200years of the Republic Each man wears a Montefortino-style helmet topped by a flowing, horse hair crest. They wear mail armour fastening over the shoulders and reaching down to well below the hips The shield is the oval scutum constructed from plywood covered with leather to give it both strength and flexibility.

The gladius : At some point in the 3rd or very early 2nd centuries вс, the Romans adopted the ‘Spanish sword’ (gladius hispaniensis) as their principal sidearm, replacing the various short, thrusting types in use before this. Copied from a Spanish design, the Romans may have first come across this weapon when facing Iberian mercenaries in Carthaginian employ during the First Punic War or when the first Roman armies campaigned in the Spanish peninsula during the Second War. It was a point of pride for the Romans to be willing to copy and employ the effective tactics or equipment of their enemies, and this was not the only example of this practice. Mail armour, cavalry harnesses and saddles and some tactics were all to be copied from the Gauls. Debate continues to rage over when the Romans adopted the Spanish sword and precisely which type of native weapon was copied.

Only a very small number of Roman swords dating to the Mid Republic have been discovered. The sample is really too small to make it certain that this was normal, but all are somewhat longer than the types used by the later professional army. They are well-balanced blades, primarily designed for thrusting but also capable of delivering an effective slash. Livy claims that in 200 BC a Macedonian army was dismayed to see corpses of men killed with the Spanish sword, and describes horrific wounds, such as heads and limbs severed from the body, all of which were the result of cuts.

Legionaries of the Late 3rd Century BC

This scene shows a group of legionaries on campaign at the beginning of the Second Punic War (218-201 вс). Like soldiers throughout history, Roman legionaries doubtless spent much of their time waiting, and this group are playing dice - a common passion amongst Romans of all classes for many centuries. On the left is a hastatus or princeps, standing beside him is a veles, while a veteran of the triarii kneels on the right.

These short-term citizen soldiers provided their own equipment and therefore show considerably more variation in clothing, armour and weapons than troops of the later professional legions. However, evidence for equipment and dress in this period is comparatively poor and much of this illustration remains conjectural.

The pugio

Some Roman soldiers carried a dagger (pugio) as well as a sword. Although Polybius does not mention daggers, examples have been found in what is probably a 2nd-century BC context in Spain. The pugio provided an additional weapon, but was probably more often employed in the day-to-day tasks of living on campaign. The later practice was to wear the pugio on the left hip and the gladius on the right.

The spear

Although Polybius tells us that the first two lines of infantry were equipped with the pilum, the third line, the triarii, still employed the old hoplite spear. This was a heavy weapon, intended for thrusting and not throwing. On one occasion in 223 BC the triarii's spears were taken from them and issued to the hastati, who then kept in close formation to weather the initial storm of a Gallic charge. Dionysius of Halicarnassus claims that in the war with Pyrrhus the principes had also used spears, which they wielded two-handed. This is somewhat strange, for it is difficult to see how a man equipped with such a weapon could also have used the normal Roman shield, but some scholars have taken this to mean that the adoption of the pilum was a gradual process and that all three lines had originally been spearmen. The evidence is too poor to resolve this question.

Defensive equipment

Body armour: Several types of body armour were in use at this period. The most expensive and best was mail, consisting of a cuirass made from linked iron rings. This offered good protection and was flexible enough to permit relatively easy movement. Its only disadvantage was that it was also heavy. Most of the weight fell on the wearer’s shoulders, although a belt helped to spread this. Mail appears to have been copied from the Gallic tribes of northern Italy, and may have been a Celtic invention. Roman and some Celtic mail shirts were reinforced by a double layer on the shoulders to protect against downward cuts.

Some men may have worn scale armour consisting of small bronze plates. Less flexible than mail, such a cuirass could be polished to a high sheen to look more impressive. Many men wore a greave to protect their left leg, the one nearest the enemy. Senior officers and some cavalrymen appear to have used various forms of muscled cuirass, probably usually of bronze. Some form of jerkin, probably padded, was worn beneath all types of metal armour.

Not all men could afford any of these alternatives, and Polybius tells us that instead these wore a pectoral plate. Usually round or rectangular, these bronze or iron plates were fastened with straps onto the front of the chest.

Helmets: A number of helmets survive from this period, although in most cases we cannot associate them with the Roman army with absolute certainty. Since each soldier provided his own equipment it was inevitable that there was no single standard pattern of body armour or helmets in use. The commonest type of helmet was the Montefortino helmet, a high domed pattern topped by a crest knob, with a stubby neckguard and hinged cheek- pieces. Another type was the Etrusco-Corinthian, which appears to have developed from the Corinthian-type hoplite helmets. These had covered the face, obscuring hearing and allowing vision through small eye-holes, but could be pushed back and worn on top of the head more comfortably when not actually in combat. The Italian development of this was always worn in this way, though it preserved the eye holes for decoration. Some Attic types were certainly in use in southern Italy and were probably also employed by the Romans or their allies. All of these helmets were made from bronze beaten into shape.

The Montefortino was of Gallic origins, as were the similar though usually lower Coolus types which appear in the Late Republic. The Romans also began to copy some iron Celtic helmets, such as the Agen and Port types. These fitted better to the head and had broader cheek-pieces which offered superior protection to the face. The design of Roman helmets until Late Antiquity would owe much to all these patterns already in use in the Republic.

A statue of a young Gallic nobleman from Vaclieres in southern France, providing a good image of the Gauls who fought against and as auxiliaries with Roman armies It is quite possible that the Romans copied the design of the mail cuirass from the Gauls, for the features shown clearly here - notably the shoulder doubling - are characteristic of the mail worn by the Roman army. The torque worn as decoration around the neck would later be adopted as an award for bravery by the Roman army.

Cavalry seem to have worn most or all of these types. However, Boeotian helmets, a Greek design specifically intended for horsemen, seem also to have been in use.

The shield (scutum): Polybius describes the shield carried by the heavy infantry as semi-cylindrical and about 1.2 m (4 ft) in length and 76 cm (2 ft 6 in) in width. Sculptural evidence shows that it was normally oval in shape. It was made from two layers of plywood, the boards laid at right angles to each other, and the whole thing covered with calfskin. This combination gave both strength and flexibility. Iron binding protected the top and bottom to prevent the layers from splitting as a result of blows, and in the centre was an iron boss.

The only example of a shield of this pattern was found at Kasr el-Harit in Egypt. It is probably, though not certainly, Roman. It does not have a metal boss, but a wooden, barley-corn-shaped boss covering the horizontal hand-grip. A reconstruction modelled on this example weighed 10 kg (22 lb), heavier even than the bulky hoplon, and unlike the hoplite shield all of the weight was supported in the left hand as there was no shoulder strap for use in battle.

A diagram showing the construction of a shield (scutum) based on the example found in Egypt and the description given in Polybius. Although heavy, the oval scutum offered very good protection. It could also be used offensively to knock down or unbalance an opponent.

Roman cavalry employed significantly smaller and lighter shields, which appear to have been round. Rather unhelpfully, Polybius describes an obsolete pattern of cavalry shield, but not the type actually employed by the equites in his day.

(Below) A badly corroded relief from the Aemilius Paullus monument at Delphi commemorating the Romans ’ defeat of King Perseus of Macedon on 22 June 168 вс On the left of the picture two Roman horsemen charge into contact with Macedonian cavalrymen, one of whose horses is collapsing The Romans wear mail armour very similar in design to that of the Vacheres warrior.

(Below) This plan of Camp III at Renieblas near the site of the siege of Numantia, Spain, followed Schulten’s excavations in the early 20th century.

(Below) Schulten claimed that these forts were organized similarly to the marching camp described by Polybius.

(Above) A diagram based upon Polybius’ description of the marching camp laid out by a consular army of two legions and two alae Each section of the legion - the three tines of heavy infantry and the cavalry - occupied its own area. A series of lanes leading to the two main roads allowed the troops to form up easily.

The camp and military life

The militia army was always essentially impermanent, and it seems that, even when legions remained in existence for some time, they were re-numbered at the beginning of each consular year. Men were enrolled, and served usually for no more than the duration of a campaign and returned to civilian life. The Romans had instituted pay for their soldiers in 396 BC, but this covered no more than basic living expenses and was not a significant source of income. The prospect of booty may have attracted some soldiers, especially when the enemy was perceived to be wealthy, for plunder was supposed to be fairly distributed throughout the army. However, most citizens served because they closely identified themselves with the state. For the duration of their military service, Roman citizens willingly submitted to an extremely harsh system of discipline, losing most of the legal rights which protected them in civilian life. Soldiers could be flogged or executed on the command of their officers. Cowardice brought the death penalty, as did sleeping on guard duty, and also such crimes as theft and sodomy within the camp. Both legally and ideologically, a marked distinction was maintained between the status and appropriate behaviour of Romans at home (domi) and at war (militiae). Enrolment into the legions took place on the Campus Martius or ‘Field of Mars’, outside the formal boundary of the city to signify this change. The legions were only permitted into Rome itself on the day of a general’s triumph, when he and they paraded through the streets to mark their victory over the enemy.

The temporary camps constructed by the Roman army symbolized the ordered existence of citizens whilst they served in the legions. Polybius describes in some detail the design and construction of the marching camps. At the end of each day’s march a Roman force followed a standard plan as it laid down streets, tent-lines and horse-lines surrounded by a ditch and rampart. Each maniple knew where it would sleep and what duties it would perform, since fatigues were allocated according to a regular system. Pyrrhus is supposed to have realized that he was not dealing with mere barbarians when he saw the order of the Roman camp.

Archaeology has discovered very few temporary camps from this period. However, a series of camps around the Celtiberian stronghold of Numantia (near modern-day Burgos in Spain) appear to date to the 2nd century BC. Several camps were evidently occupied for more than just a night or two, for they show traces of simple internal buildings, corresponding to the tents of an ordinary marching camp. The best-preserved camp of a series at Renieblas can with the eye of faith be seen to reflect some features of the Polybian camp, with the legions divided into lines and maniples.

The marching camp offered protection against surprise attack. Day and night pickets were main tained at a set distance beyond the ramparts to warn of any attack and slow the enemy down. Troops performing this duty were bound with a solemn oath not to abandon their position. Normally the rampart and ditch surrounding the camp were sufficient only to delay attackers and not to stop them, although if the army remained in the same camp for some time then its defences could be made far more formidable. The Romans rarely, if ever, planned to fight from inside the walls of their camp, but to advance and meet the enemy in the open, relying on the resilience and tactical strength of the legions. Between the ramparts and tent-lines of a camp was a wide open area known as the intervallum, which ensured that the tents were out of range of missiles thrown or shot from outside the camp. More importantly, this space allowed the army to form itself up ready to deploy into battle order. Three columns would be formed, with sometimes a fourth for the cavalry. Each column would become one of the three lines, and the maniples were positioned in the order they would take up in the fighting line, with the unit that would form on the right heading the column, and the one on the left at the rear. Each column would march from one of the four gates of the camp to the position where battle order was to be formed. The temporary camp played a vital role in allowing Roman armies to enter battle in an organized manner.

A section of the relief from the Domitius Ahenobarbus monument showing a figure - possibly intended to represent the war god Mars - dressed in the uniform of a senior officer of the Republican army. The six tribunes who commanded each manipular legion would probably have closely resembled this man.

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