CHAPTER 10
MICHAEL SAGE
THERE are serious difficulties in tracing the history of Roman military formations and tactics during the Republic.1 The Latin annalistic tradition presents a static picture, projecting the characteristics of the army of the Middle Republic back into the earliest period. In addition, it is for the most part uninterested in the technical aspects of warfare (cf. Rawson 1971: 13–31; Schleussener 1978: 101–10). There are occasional exceptions to this indifference but they mostly concern modifications to weapons such as changes in the pilum ascribed to Marius and Caesar and seem to be more the product of interest in well-known historical figures than in military development. Polybius’s history forms a major exception with his detailed discussion of the organization and equipment of the contemporary Roman army in Book 6 and his comparison of the manipular formation to the Macedonian phalanx in Book 18 as well as in his accounts of the major battles and scattered comments throughout the rest of his work (Polyb. 18.28.1–32.5).
The extant fragments of antiquarian writing are more helpful. They provide the basis for much of our understanding of early military organization and tactics. It is likely that antiquarian sources lie behind the digressions on the Servian army in Livy, Cicero, and Dionysius of Halicarnassus. The fragmentary nature of most of the extant material and its narrow focus prevents it from offering a coherent account. At most it can serve as a starting point for the construction of one.
Military manuals also provide little help in any reconstruction (see further Lovano, 79–80). The earliest known Latin manual, that of Cato (De Re Militari, c. 160), is extant only in fragments (Jordan 1860: 80–2). It does show some interest in the history of the Roman army and seems to have dealt with practical military matters including military organization and battle formations. The extant manuals are all of imperial date and present an interesting dichotomy. The majority of manuals dating from the early empire either focus on stratagems in the field or the role of the commander. They show little interest in the technical details of soldiering with a few exceptions such as Arrian’s Tactica or Pseudo-Hyginus’s treatise on the Roman camp. The emphases change in the late Empire and early Byzantine period. Vegetius’s De Re Militari and the Strategikon of the Emperor Maurice are far more concerned with the practical aspects of war such as training, battle formations, and armament. The reasons for such a change are not clear, but the more difficult military situation of the late Empire may have contributed to the change of emphasis (on imperial military manuals: Campbell 1987: 13–29). These handbooks reflect the same attitude to warfare found in most historical narratives that also focus on the moral qualities of the commanders and their troops.
This lack of interest in the technical aspects of warfare severely hinders any attempt to reconstruct the history of the Roman army and tactics. It is a striking fact that there is no ancient account of major innovations in tactics and organization such as the development of the manipular legion or the shift from the maniple to the cohort as the basic tactical unit of the Roman army.
Material remains and literary descriptions of weapons can be useful aids, especially so for the earlier periods. Since the type of equipment an army uses bears a close relation to the formations it adopts, equipment can be used as basis for inferences about military techniques. It is also useful in tracing external military influences on Roman practice (cf. Couissin 1926, Connolly 1981, Bishop and Coulston 1989).
Rome’s earliest military formations were of two types. The first type was an army of the community as a whole. The sources claim it consisted of three thousand infantry and three hundred cavalry with one thousand infantry and one hundred cavalry drawn from each of the three tribes (Varro, Ling. 5.89; Livy 1.13.8; Plut. Rom. 13.1). The authenticity of these numbers gains support from the continuing importance of multiples of three in the Roman army: the sixty centuries in a legion, the three lines of the manipular army, and the three hundred cavalry which were a standard complement of the legion in the Republican period. The king or his deputies functioned as overall commanders. There is some evidence for subordinate commanders of both cavalry and infantry. Tribuni celerumare mentioned as cavalry commanders, perhaps one for each tribal contingent, and had as their subordinates the decuriones whose title survived in the later Roman army.2 In the absence of any evidence in the sources about subordinate officers in the infantry it is reasonable to assume that the later tribuni militum had their counterpart in the archaic army. It may be that they commanded the tribal contingents and that there were subordinate commanders of units of one hundred men, the precursors of the later centurions (tribuni militum: Ensslin 1937: 2432–92).
In addition to the regular army there were also war bands held together either by kin ties or the success of a particular leader or some combination of the two. The defeat of the Fabii at the Cremera River in 479 by a force from Veii illustrates both types of bands. The Fabian force is described as consisting of both members of the Fabian gens and clients. This is the only attested action of a clan army, but circumstantial detail associated with the story adds plausibility to it. Many details of the episode are clearly invented but there is no reason to dismiss the episode as fabrication. Further evidence for bands of this type has surfaced in the form of the so-called Lapis Satricanus, an inscription with what appears to be a dedication to Mars by a war band in honor of their leader.3
Any attempt to reconstruct the fighting techniques of either the Roman army of this period or the war bands must depend upon weapons finds and pictorial representation of combat as the literary sources are unhelpful (see further Connolly 1991: 358–63). There have been few finds of weapons or other military equipment at the site of Rome from this period. Pictorial representations of combat are also rare. Comparison with other sites in Latium and southern Etruria suggests that before the end of the seventh century throwing spears or javelins often combined with a sword or other weapon suitable for close combat were the most common weapons. In both Latium and at the site of Rome there is little trace of protective armor and it is probable that such equipment was made of organic materials (Stary 1981: 20–159). Although there can be no certainty, the weapons used point to fighting in relatively open formations, as space would be needed to employ missile weapons. Representations of combat from Dark Age Greece may offer us some idea of what this fighting was like (Snodgrass 1964; Ahlberg 1971). The remains of a chariot have been found in an eighth-century grave at Rome (Esquiline 94) and at later sites in Latium but there is no evidence for its use in warfare.4 Etruscan representations which may be relevant for Rome show mounted infantry rather than true cavalry fighting from horseback.
The end of the seventh and the first half of the sixth century are marked by the beginnings of urbanization and by a substantial population increase at Rome. Weapon finds as well as representations of fighting at Rome and elsewhere in Latium become more plentiful. Of more importance is the evidence from the mid-seventh century for the adoption of hoplite equipment in Etruria and representation of hoplite warriors at Rome and in Latium (Saulnier 1980: 69ff.; Stary 1981: 63ff). These developments form a suitable context for the military reform traditionally ascribed to Servius Tullius. The main evidence for it is provided by digressions in Livy and Dionysius of Halicarnassus (Livy 1.42.5–43.10; Dion. Hal. Ant. Rom. 4.16–18; Cic. Rep. 22.39–41 adds little; for recent discussion see Cornell 1995: 179–86). Their accounts are in substantial agreement with only a few minor differences. The hoplite military reform was tied to the introduction of a property census which linked military service to wealth, since individuals served at their own expense. This simply may have institutionalized the preexisting situation as service in the archaic army must have been on the same basis.
The complicated five-class structure as well as the division of centuries within each class found in these accounts are anachronistic and are to be linked with later political developments. Some sources preserve a simpler distinction which seems to be authentic between classis and infra classem, that is, between service as heavy or light infantry (Paul. Fest. 100L, Gell. NA 6.13).
The equipment assigned to the first class of forty centuries was the full hoplite panoply of round shield, cuirass, helmet, and greaves. Its offensive weapons were also those of the hoplite: the heavy thrusting spear with a sword as secondary armament. The second and third classes wore fewer pieces of protective equipment but still carried the same offensive weapons. The last two classes were light-armed infantry.
The first class is clearly equipped to fight in the manner of a Greek phalanx. However, difficulty has arisen about its relationship to the second and third class whose principal defensive equipment is the scutum or long rectangular shield (see further Eichberg 1987: 175). This difficulty is due to an overly narrow concept of how early phalanxes fought. The compact, regular arrangement of the Greek phalanx into ranks and files was a gradual development. The Greek phalanx of the seventh and sixth century was much more fluid than it was later to become (van Wees 2004: 170–83, dates the development of the classical phalanx to the last half of the fifth century; the beginning of the fifth seems more likely). Apparently warriors were mobile within the phalanx and changed position in response to the rhythm of the fighting. Light-armed infantry seem to have fought within the phalanx. The adoption of hoplite equipment seems to have been piecemeal and so hoplites both in Italy and Greece must have normally operated with troops armed with other equipment.
Sixty centuries of heavy armed infantry would give a paper strength of six thousand men; this seems compatible with modern estimates for the population of Rome in the late sixth century (Ampolo 1980: 29–30 estimates a population of 20,000 to 30,000 which he calculates could field an army of 6,000 to 8,500 men). The sources also record an increase in the number of cavalry centuries at the same time.5 This lends support to the view that the reform had two principal objects, the creation of a hoplite force and as means to enlarge the available pool of men available for military service.
The transition to the Republic at the end of the sixth century and the institution of the dual magistracy of the consuls led to a splitting of what had been a single “legion” into two legions with three thousand heavy infantry each.6 This figure agrees with the number of heavy infantry in the legion of the middle Republic. There is no evidence as to how the Servian legion and its immediate Republican successors were deployed on the battlefield or the manner in which they fought. The narratives of early regal and Republican battles stress the importance of the cavalry, which is often portrayed as fighting dismounted. Given the relatively minor role of Roman cavalry in later centuries it seems likely that this is annalistic invention.7
By the middle of the second century the Roman army had undergone a tactical revolution. The rectangular, comparatively densely packed phalanx was no longer the basic tactical unit on the battlefield. It had been had been replaced by the maniple, a miniature phalanx that could operate independently. The maniples of heavy infantry were divided among three lines each of ten maniples: from front to back the hastati, principes, and triarii, and within each line they were separated by intervals equal to the frontage of the maniple. The maniples were arranged in checkerboard fashion so that each line covered the intervals between the units of the line to its front. The maniples of the hastati and principes were 120-men strong while those of the triarii contained half that paper strength number. The maniples of the hastati and principes were rectangular in form while those of the triarii were arrayed in column. This tactical arrangement allowed the Romans to commit their troops to battle in successive waves while retaining a reserve force (figure 10.1).
Figure 10.1 Tactical arrangement of the Roman legion in the mid-second century. Drawing after M. Sage.
The change in the battle line was accompanied by a change in weaponry. The heavy thrusting spear was replaced as the main offensive weapon in the front two lines by a combination of a javelin, the pilum, and a short sword effective both for thrusting and slashing. The round shield of the first class was exchanged for a large oval shield, the scutum, with a central handgrip that allowed it to be quickly turned in any direction. The triarii retained the long thrusting spear until the end of the second century.8 These weapons allowed the maniples to quickly redeploy and face a threat from any direction. As Polybius points out in his comparison of the Macedonian phalanx to the manipular formation, maniples could fight successfully in the kind of rough terrain which broke the cohesion of the phalanx, rendering it vulnerable. The Roman system committed only a portion of its troops to the initial attack and allowed independent maneuver of units that was far more effective in countering such threats. The use of the sword and pilum reduced the need to disengage the entire formation to meet flank attacks. The comparatively small size of these units also increased their mobility as smaller units could move more quickly.9 Even Hellenistic armies that depended on the phalanx normally operated in separate divisions (Polyb. 18. 29–32 compares the phalanx to the legion to the advantage to the latter).
This adoption of new weaponry increased the value of the infantry in battle. The pilum appears to have been an effective substitute for other types of missile. Within its limited range (about 28 m) it was highly effective in penetrating both shield and armor. In addition, it was designed to bend on impact so that the enemy could not return it. It also could be used to repel cavalry attacks as Caesar did at Pharsalus in 48 (Caes. B Civ. 3.93.5–6; Plut. Caes. 45.2; the pilum in battle: Zhmodikov 2000: 67–78). The standard “Spanish sword” of the legionary was more lethal than the heavy thrusting spear of the phalanx. When Philip V had the cavalry killed at Cynoscephalae buried, the public was appalled by the horrific wounds inflicted by the legionary sword (Livy 31.34.1–5).
In addition to the heavily armed legionaries the legion of the mid-second century contained twelve hundred light-armed troops. Although Polybius (6.24.2) states that forty were assigned to each maniple, this must have been for administrative purposes only. In battle narratives they operate independently of the heavy infantry and from the mid-third century often worked in conjunction with the cavalry. Their offensive weapons were a lighter equivalent of the legionary’s. They carried the same sword along with multiple javelins which were lighter versions of the pilum (Polyb. 6.22).
Three hundred citizen cavalry, a preserve of the well-to-do, were also attached to the legion. They were organized in ten turmae or squadrons including two officers and twenty-eight troopers. Their small numbers and the inability of ancient cavalry to ride down organized heavy infantry relegated them to subsidiary roles on the battlefield. They were normally stationed on the wings of the infantry to protect their flanks and one of their most important tasks was to drive off enemy cavalry so as to expose the enemy’s. They were useful as a screen for infantry movements, protecting foraging parties, as scouts, and, if the enemy broke, in pursuit (cf. McCall 2002: 13–21 who argues that Roman cavalry were effective).
These changes in equipment and tactics placed greater emphasis on skills of the individual soldier and the need for discipline and cohesion as the army was now required to carry out more complicated maneuvers in battle. However, there is no evidence in the Republican period for any regularized course of training. Historians do mention training but it appears to have been conducted at the discretion of the commander. After his capture of Carthago Nova in 209 Scipio Africanus instituted training in marching and weapons practice at his own initiative (Polyb. 10.20; Livy 26.51). Training methods as well were dependent on the commander. There does seem to have been a standard pattern. Livy mentions (24.58) that a Roman centurion, Q. Statorius, was sent to drill Numidian recruits in the Roman manner in 213. This must have included some weapons drill. The sources mention the introduction of weapons training based on the methods employed in the gladiatorial schools in the face of the impending German threat in 105 (Frontin. Str. 4.1.12). Nevertheless, Roman commanders must have regularly trained their men and were conscious of the limitations of new and relatively untrained troops. In 193 one of the consuls, Q. Minucius Thermus, while operating in Liguria, refused to engage in a decisive battle because his troops were new recruits and insufficiently trained (Livy 35.5.3).
The reasons for, and the stages that marked, the transition from the hoplite phalanx to the manipular legion are, except for scattered references, ignored by the sources. The one exception is a topos found in Greek sources that the Romans borrowed their fighting methods from their enemies and then used them to defeat them (the theme appears in Sall. Cat. 51.7 and must have been a Roman commonplace; cf. Ineditum Vaticanum 3 [FGrH 839 F1], Diod. Sic. 23.2.1, Ath. 6.273). It connects the change from phalanx to maniple to the fourth-century conflicts with the Samnites as it ascribes the earlier adoption of the phalanx to wars against the Etruscans. The artificiality of this is clear. The adoption of the phalanx was far more likely due to Greek influence in central Italy. The only plausible explanation for the development of the manipular formation in the Samnite Wars was the need to engage the enemy in the irregular and mountainous territory of the Samnite highlands. Such an explanation ignores the successful wars of the fifth century against the Aequi of the Anio valley or the conflicts with Celtic tribes in the first half of the fourth century. The link in this account between the adoption of Samnite weapons and tactical change also appears weak. It is extremely unlikely that the Romans lacked suitable swords or missile weapons before the late mid-fourth century.
Perhaps the more important question is why the Romans were ready to accept such changes. The fourth century was a time of other important military developments. The most striking was the increase from one to two legions in 362, the popular election of military tribunes in the same year, and a doubling of the legions to four in 311 (cf. Livy 7.5.9, 9.30.3). The increase in army size implied the need to extend the reach of the levy down the economic scale. This was made possible by the institution of army pay at some point in this period. Such a step also implies the abandonment of the census classes as the basis of the levy and its replacement by a levy based on tribal membership. This may form the background to the first attested levy of capite censi in 281/280 (Cassius Hemina, in Peter fr. 21). The need to enroll the less wealthy in the legions may have served as one motive for the development of new tactics. Other reasons remain unclear.
It seems likely that this change in tactics was accomplished gradually. Certain references in the sources point to the period between 311 and the war against Pyrrhus as the time when the transition began. Dionysius of Halicarnassus singles out the second line of the manipular legion as those who wield cavalry spears and prevail in close order fighting (Ant. Rom. 20.11.2; see Rawson 1971: 25–6). Plutarch’s Life of Pyrrhus (21.6) mentions the Romans fighting fiercely with their swords at Asculum. Together such passages imply that the first line of the legion had separated and was now fighting with the weapons of the manipular army.
Further support for this view comes from the name of the first line, the hastati. Fragments of Livius Andronicus and Ennius indicate that the term hasta could be used of a throwing spear (see Enn. Ann. 284 Vahlen; Liv. Andron. F35 Morel). The javelin of the later light-armed Roman troops was called the hasta velitaris (Livy 26.4.3). One further piece of evidence is provided by Polybius (21.6). By his time the levy was generally based on age and presumably experience. He tells us that the youngest and poorest were drafted into the light-armed velites while those somewhat older formed the hastati. Men in the prime of life were enrolled as principes while the oldest men were brigaded as triarii. This suggests the possibility that the hastati were originally formed from the light-armed of the original phalanx. The standard offensive equipment of the manipular legion was in essence a heavier version of the standard equipment of the light-armed. The need to expand the legions might well have acted as the impulse behind this development.
It appears that at first only the hastati fought in the new manner. Sometime after the Pyrrhic War the first two lines adopted sword and pilum as their offensive weapons while triarii retained the heavy thrusting spear and their formation in column. As the oldest soldiers the triarii were ill suited to the physical demands that sword fighting required. This is illustrated as well by their frequent use as a reserve or as a camp guard (Dion. Hal. Ant. Rom. 8.86.4). The retention of the thrusting spear allowed them to more effectively face cavalry and that may also explain their being arrayed in columns which eased the problem of forming up to face attacks on the flanks or to the rear.
Additionally, Roman armies included substantial numbers of allied forces in the Republican period. By the late third and second century a rough estimate is possible despite the fact that the sources give widely different figures. The ratio between allied and Roman forces varied 2:1 to 1:1 with an apparent decline from the beginning of the second century (see Brunt; his figures are accessible in Nicolet 1977: 446ff). Their tactical organization differed from that of the legions and anticipated changes in legionary organization in the first century. The allied infantry units were organized in cohorts of four to six hundred men. In a normal consular legion of the middle Republic these units were brigaded in two alae or wings of ten cohorts each. Polybius (6.26.7) claims that there was substantially more allied cavalry in a legion than Roman. He gives a figure of 3:1 but this is an approximate figure; the figures for individual armies are much more variable.
The cavalry were organized in turmae as was the Roman cavalry and it is a reasonable estimate that these units likewise consisted of about thirty men. There is general agreement that the turmae were both tactical and organizational units but the status of the infantry cohort is less clear. The evidence implies that the allied cohort was both an organizational and tactical unit. There are references to allied cohorts operating as battle groups. At Pydna in 168 the battle began as a skirmish between Thracian troops and an outpost consisting of two cohorts of Paeligni and Marrucini and a unit of allied cavalry (Livy 37.40.4; Plut. Aem. 18 differs slightly in detail). A cohors Paeligna accompanied Sulla on his mission to the Mauretanian king Bocchus in 105.10 It is likely that allied cohorts were used as tactical formations when they participated in independent operations as appears to have been the case for Roman troops by the end of the third century. The familiarity of the men with each other and shared ethnicity would have strengthened the group’s cohesiveness and eased problems of command. Further support for such a view can be found in the practice of brigading Italian cavalry together on one wing while Roman cavalry was deployed on the other.
The use of the allied cohort within the battle line is more problematic. Livy’s description of the Roman battle line at the battle of Magnesia in 190, which represents the normal Roman deployment of allied forces on the wings of the line with the legions in the center, is frequently paralleled elsewhere in the sources. Livy also mentions (37.39.7–9) that the allies were armed in identical fashion to the Romans. This implies that their tactical formation was divided into the same lines and maniples as the Roman legions were, and presumably had the normal contingent of light-armed troops as well. The cohort could still have formed the basis for the arrangement of the maniples in line. The Roman cohort can be used as a comparison. Its three maniples, one from each of the three lines and its light-armed troops, are approximately the strength of known allied formations. It seems likely that allied cohorts were structured in the same way and were brigaded as cohesive units in the battle line. The tactical organization of allied cavalry is less of a problem. Its tactical divisions were identical to Roman formations and it too was probably brigaded by place of origin.
The chronology of the increasing assimilation of allied formations and tactics to the Roman model is unknown. There is little information about the fighting styles of other Italian peoples and much has to be inferred from archaeological finds. The long-standing system of military alliances and the preponderance of Rome in central Italy probably resulted in the early Romanization of allied forces. Livy’s statement (8.8.14–15) that at the time of the Latin War Roman and Latin equipment and formations were identical is probably correct. The annalists’ descriptions of Roman battles with the Samnites are full of anachronisms, but equipment finds and pictorial representations point to a more open battle order than the phalanx that would have not made the transition to the manipular formation difficult (Salmon 1967: 102–10). Polybius mentions (18.28.10) that at the battle of Asculum in 279 Pyrrhus interspersed his southern Italian allies organized in manipular formation between units of his phalanx. The common military tradition must have made for a rapid assimilation of allied forces.
Overall command in battle was normally vested in a consul, praetor, or promagistrate with imperium. In campaigns where the two consuls were operating jointly overall command was rotated on a daily basis. Such a system could and did lead to disputes between the commanders as at Cannae in 216 between the two consuls C. Terentius Varro and L. Aemilius Paullus over the decision to give battle against Hannibal (Polyb. 3.110.1–3; Livy 22.44–45). Legates and military tribunes could command detached forces. In 168 when the Macedonian king Perseus had taken up an entrenched and well-protected position near Pydna, a force of 8,200 infantry and 120 cavalry placed by Aemilius Paullus under Scipio Nasica serving as military tribune successfully turned the king’s position (Plut. Aem. 15–17; Livy 37.35.14–15). Delegation of command increased with the growth of the Empire. Caesar, faced with the need to control large areas in Gaul, routinely used legates in detached commands. The allied infantry alae were under the command of Roman praefecti socium of equestrian rank. Since each ala was of legionary size it has plausibly been suggested that it had six praefecti in parallel to the six military tribunes of the legion (Keppie 1984: 23). Both Roman and allied cavalry were normally placed under subordinate commanders as they often operated independently of the infantry (later legates are often found commanding the whole of the cavalry).
Given the limitations in communications and signaling in ancient armies the battle line was divided into a center and two wings since it was impossible for a single commander to control the entire line. Military tribunes often exercised such subordinate commands before the beginning of the second century, but that role was increasingly taken over by senatorial legates. In the climatic battle of the war against Antiochus III at Magnesia ad Sipylum in 190 the Roman force consisting of two legions together with the Italian and Greek allies was under the overall command of the consul L. Cornelius Scipio who directly commanded the right of the line while his legate commanded the left (App. Syr. 31.6).
The deployment of the manipular battle line in general followed a standard pattern with the legions in the center, the alae of the allied infantry on their flanks, with the cavalry stationed on the wings. The placement of the light-armed velites varied according to circumstances. They were normally placed in the gaps between the maniples of the first two lines, but either at the opening of battle or during its course they were often brigaded with the cavalry and acted in conjunction with them. The capabilities of the manipular battle formation are best revealed by Scipio Africanus’s major battles in Spain. At Baecula in 208 he reversed the normal battle line by holding the enemy’s center with his light infantry and extending his heavy infantry on the wings of his lines to attack the enemy’s flanks (Polyb. 10.39.3–6). These tactics were developed further at Ilipa in 206, where Scipio placed his unreliable Spanish allies in the center, which deprived the Carthaginians of the effective use of their best troops, and as he neared the enemy marched his right and left wings out beyond the enemy line and successfully attacked the Carthaginian flanks (Polyb. 11.22.6–23.9). The advantages of a segmented formation are also evident at Cynoscephalae when twenty maniples were detached from the victorious Roman right wing, marched behind the battle line, and then delivered an assault against the flank and rear of the Macedonian right (Polyb. 18.26.1–3; Livy 33.9.8–9).
Once the decision for battle had been taken the first task facing the army was the deployment from column of march into line formation. It seems likely based on imperial evidence that the march to the field of battle was carried out under the supervision of the centurions with each of the three lines separated from each other and intervals left between maniples to avoid disordering their formation. This would allow the maniples to quickly wheel into line.
The maniples of all three lines would then take up their positions in checkerboard or quincunx fashion. The maniples of triarii containing thirty men or half the strength of the other two lines would take up an essentially defensive position in column, kneeling with their left leg extended, resting their shields on their shoulders. References to their being moved forward to the front of the formation during a battle are extremely rare, though Scipio Africanus did place them on the wings of the other lines in the second phase at Zama (Polyb. 15.14.3; Livy 30.34.11). The striking power of the legion was concentrated in its first two lines. Usually the maniples would be separated by gaps equal to their frontage but their width and the spacing between the lines could be varied according to circumstances.
The two centuries of the maniple were commanded by two centurions, the prior and posterior. The prior, the senior of the two, commanded the maniple’s right and was in overall command of the unit while the posterior commanded its left. The signiferi who carried the unit’s standards could exercise command if the centurions were unable to do so.
The sources provide no help in understanding how the maniple itself was deployed. Various arguments have centered on the question of whether the centuries in the maniple were arrayed behind one another or side by side. No definitive answer is possible. The titles of the centurions offer no help as we cannot be certain of their origin. The fact that one centurion commanded each side of the maniple makes it more probable that each centurion would be directly commanding the men who belonged to his unit and so it is likely that the centuries were arrayed side by side. The depth of the maniple presents a similar problem. Certain considerations support a depth of six men. The use of the sword, pilum, and scutum limited the useful depth of the maniple. Too great a depth would not allow the rear ranks to use their pila for fear of striking the men in front. The Roman short sword could only be effectively wielded by the first line and perhaps the second rank in support. The central handgrip of the Roman shield was not suitable for transmitting pressure along a line of men and so the rear ranks could not have contributed to any attempt to break through the enemy ranks by pushing or shoving. The rear ranks must have served to replace those who had been killed or injured at the front as the battle developed. Too great a depth would simply have removed a number of men from any effective role in the early phases of the struggle. Marching formations provide some other evidence. Usually the three lines marched abreast of one another in separate maniples. A deep maniple would have reduced the usefulness of such a marching formation especially in rugged terrain. Imperial evidence suggests a width of six men in column of march and there is no reason not to assume the same width in the Republican period.11 This would support a depth of six men in the maniple.
Light-armed troops and cavalry were sent forward in the opening phase of the battle to protect and screen. The light infantry engaged the enemy’s light-armed but such contact was never decisive. It then withdrew filtering through the intervals between maniples and to the wings where it fought with the cavalry. Once the enemy infantry was held in front by the legionaries the cavalry and light-armed could deliver attacks on the flanks and rear of the enemy.
The crucial role in a set-piece battle was played by the heavy infantry. The Roman preference was to take the offensive. This attitude is clear from Caesar’s critique of Pompey at Pharsalus for keeping his inexperienced legions on the defensive to receive Caesar’s charge. He claims that by doing so Pompey forfeited the effect of the excitement and enthusiasm that accompanies the desire for battle (Caes. B Civ.3.92.4–5).
The maniples of the first line must have advanced fairly slowly to keep their ranks dressed until they came within pilum range of the enemy. A halt at this point has been denied by some scholars as it checked the infantry’s impetus. This would be more significant for a phalanx formation than for legionaries who depended on the short sword as their primary offensive weapon. At this point the maniples must have been in more open formation to allow the pila to be used effectively. The function of the pilum was to inflict casualties and disorganize the enemy line. After discharge of pila the maniples must have closed up and moved forward to contact at a quickened but controlled pace to keep formation. Debate has arisen on whether the Roman line encountered the enemy as an unbroken line or with intervals between maniples maintained. The sources are silent on the matter but certain considerations can be advanced.
It has been claimed that the maintenance of intervals of whatever size would expose the maniple to flank and rear attacks. The rear ranks of the maniple and the presence of the second line would quickly meet such threats. If the line was closed at contact the second line would not have been able to come up to replace the first as it would have been impossible to easily disengage once the battle had started. Initially contact must have been made with both shield and sword. The initial spacing between men was probably two feet to either side to allow free use of the large shield and for swordplay.
The Romans preferred to fight in a semi-crouch which allowed the preferred stabbing stroke while minimizing exposure (Dion. Hal. Ant. Rom. 14.10.18; their helmet seems to have been specifically designed to protect troops fighting in a crouched position; see Bishop and Coulston 1989: 203). Sword fighting is exhausting and the battle must have ebbed and flowed with periods of intense fighting alternating with lulls to allow the soldiers to recuperate. The intervals would have permitted men from the rear ranks of the maniple to replace the dead or injured in the front lines. It must also have been during such pauses that the hastati withdrew and the principes came up through the intervals in their line to replace them. The use of these fresh troops against an already tired enemy must often have been decisive in throwing the enemy into disorder and breaking his cohesion (Goldsworthy 1996: 171–249 offers a convincing account of the nature of Roman battle; for morale as a factor see Lee 1996: 199–217). In ancient massed battle once cohesion was lost defeat was certain. It was in the course of the pursuit, most often by the cavalry and light-armed, that the heaviest casualties were incurred by the losing side (see Sabin 2000: 5–6; Brunt: 694–7).
Sometime at the end of the second or beginning of the first century the basic tactical unit of the Roman battle line underwent a major change (see Bell 1965: 404–22, for the classic account of the development of the cohort as a tactical unit). The maniple of 120 men was replaced by the cohort of four to six hundred men that had been standard for allied infantry.
Tracing this new development presents the same problems as those that arise in examining the rise of the manipular legion. The imprecision of the sources and the difficulties in understanding their terminology for various tactical units is compounded by historical anachronism. Livy anachronistically mentions legionary cohorts as early as 446 and they appear sporadically in his account of Rome’s early wars (3.69.7). None of these early references can be accepted as they are the result of his anachronistic picture of the early army.
The first secure attestation of the unit occurs in Polybius’s description of Scipio’s tactics at Ilipa. He says that Scipio performed his maneuver with a unit of three maniples and their attached velites which the Romans called a cohort. Polybius refers again to Scipio’s use of cohorts at a battle near the Ebro later in the same year (11.23.1–2, 11.33.1 [Ebro]). Polybius’s reference appears to indicate that this was not a new formation. Livy most frequently refers to cohorts operating in Spain although he also mentions maniples. Maniples dominate his account of warfare in Greece and the eastern Mediterranean (Bell 1965). The most reasonable explanation for this difference can be found in the needs of these two theaters. In Spain campaigns were often conducted against widely dispersed tribes that waged irregular warfare as opposed to the formal set-piece battles and sieges characteristic of warfare in the East. Warfare in the West required operational groups smaller than the legions, capable of quick movement and able to protect themselves. Individual maniples were too small to operate independently. The cohort was in effect a miniature legion composed of maniples that normally fought together and supported each other in battle (Fraccaro 1975: 142). It was large enough to defend itself and fight as an independent unit and when necessary could be easily re-formed into a legion. In the Spanish campaigns cohorts fulfilled many different functions. They are mentioned as city garrisons, formed a reserve, or were dispatched on independent operations (garrison [B Afr. 9]; reserve [Frontin. Str. 2.3.22]; independent operations [Val. Max. 2.7.10]).
The dating of the transition of the cohort from a unit of maneuver to the basic tactical unit of the Roman battle line remains problematic. The last clear reference to the use of the maniple occurs in Sallust’s account of Metellus’s operations against Jugurtha.12Cohorts are also mentioned. In North Africa as well as Spain units were needed that could operate against a dispersed and elusive foe. By the time of Caesar’s campaigns in Gaul the cohort had become the standard tactical unit. One change seems to have already taken place by the 120s. All of the legion’s lines were now armed with sword and pilum. The fact that the war against Jugurtha contains the last explicit reference to maniples has prompted the suggestion that Marius was responsible. However there is no ancient evidence for this despite the fact that the sources credit other military reforms to him. It has been suggested that the change should be linked to the campaigns against the Cimbri and Teutones and the training reforms of 105, but again there is no necessary connection. Roman forces had defeated Celtic forces fighting in a similar manner for several centuries before Marius (Parker 1958: 27–9).
Although there is no definite evidence the period of the Social War seems the most likely time for the transition. The Italian allies had long been formed in such units. They also were equipped in the same manner as legionaries. The difficulties the war presented may have provided the impetus to utilize the cohort in a new way to match the Italians. After the granting of citizenship to the allies the need to integrate Italians into the legions would have facilitated a process. The changes in the order of battle would have required new training methods and the creation of a new chain of command.
The division of the legion into ten tactical units in place of the thirty of the manipular legion offered certain advantages. It simplified the chain of command and so must have speeded the transmission of orders and facilitated the movement of troops in the course of battle. This must have been especially significant in the larger armies that were fielded in the last century of the Republic. Strangely, unlike the praefectus cohortis of the earlier allied formations no commander of the cohort is mentioned. The general view is that command belonged to the senior centurion of the cohort. The cohort also offered a greater concentration of force and a larger number of troops to support the front line at its point of contact with the enemy.
The change to the cohort did not lead to major differences in the way that the elements of the line were deployed. Typically the cohorts of a legion were deployed in three lines with four cohorts in the first line, three in the second, and a third line with three cohorts. The first two lines remained the main striking force with the third as a reserve. Other formations were possible which would not have been the case with a manipular line. At Ilerda in July 49 Afranius drew up the cohorts of five legions in two lines with auxiliary cohorts in reserve (Caes. B Civ. 1.83.1–2). At Pharsalus in 48 Caesar drew up his legionary cohorts in four lines with the rear rank assigned to counter Pompeian cavalry (Caes. B Civ. 3.89.1–4). Once in Africa in 46 Caesar drew up his cohorts in a single line (Caes. B. Afr. 13.2). This highly unusual formation was employed to extend Caesar’s line as much as possible to counter attacks by the enemy’s light infantry and cavalry. These examples make clear the greater flexibility that the cohort offered as well as its ability to allow the mixing of formations from different legions as need arose.
The deployment of the cohort raises as many problems as that of the maniple. Its normal size appears to have been between four and five hundred men, but the number varied far more than was the case with the maniple; at Pharsalus Pompey’s cohorts numbered about four hundred men while Caesar’s numbered 275 (so Brunt: 691–2). The depth and frontage of the cohort are problematic. Frontinus, not the most trustworthy of sources, informs us that at Pharsalus Pompey’s cohorts were arrayed ten deep (Str. 2.3.22). Even if this number is right it cannot serve as a basis for generalization. Pompey’s legions were far less experienced than Caesar’s and he employed this unusual depth to steady his men. Josephus in recounting Vespasian’s march into Galilee during the Jewish rebellion (ad 66) mentions that the legionaries marched in six columns (BJ 3.124). If this were the normal depth of the cohort it would have simplified and quickened the transition from column into line. It seems likely that depth must have varied greatly depending on a host of variables such as the experience of the troops, the ground, and the length of the opposing line. Although it has been suggested that just before contact with the enemy gaps between the cohorts were closed up, it seems as unlikely as in the case of the maniple and for the same reasons
The period that witnessed the transition from the maniple to the cohort as the standard tactical unit was also marked by two further important developments in the way Rome waged war. The first was the disappearance of the velites. As in the case of the maniple, the last clear reference to them occurs during Metellus’s campaign against Jugurtha (Sall. Iug. 46.7). Frontinus’s Stratagems mentions (2.3.17) them serving with Sulla at Orchomenus in 86, but his accuracy is often problematic. The disappearance of the veliteshas also been ascribed to Marius but there is no evidence that he was responsible. It is more likely that it was the indirect result of his levying men from the capite censi and Rome’s increased military needs in the first century that resulted in their disappearance. The light-armed had been levied from the youngest and poorest. With the disappearance of a minimum property requirement for service the prospect of serving in the more prestigious and probably better-rewarded legions would have reduced the number of those willing to serve. In addition, the number of legions in service increased in the first century. In the period after 167 there were probably about eight legions in service, while in the period down to 50 the number had risen to twelve to fourteen.13 The greater need for legionaries must have made the Roman state more willing to enroll men as legionaries who earlier would have served as velites.
A third element in this transformation was the growth of Rome’s empire and her increasing influence outside its limits. We have little information on the use of non-Italians in Rome’s armies before the Second Punic War. Scipio Africanus extensively employed Spanish and Numidian troops in Spain and North Africa. The Aetolians and other Greek allies played a major role in the course of the second century campaigns in the Balkans and Asia Minor. With the granting of citizenship to the Italians after the Social War the use of foreign troops must have substantially increased now that Italians were no longer available. They had two important advantages over Roman light-armed infantry. They normally did not receive pay and many of the peoples employed could supply skills that Roman troops lacked, such as Balearic slingers or Numidian light cavalry. The value of such troops varied tremendously. During the civil war Caesar’s German and Gallic cavalry played a major role in his success while the eastern levies that Pompey assembled at Pharsalus seem to have been ineffective.
The final major change of the period is the disappearance of Roman and Italian cavalry (McCall 2002: 101–39). Dating the end of such service is difficult. There is good evidence for the service of Roman and Italian cavalry in Spain in 140 and in the war against Jugurtha. In addition there is strong evidence for service by Roman cavalry against the Cimbri in 102.14 There is none for cavalry service in the Social War, and Roman cavalry did not reappear until the extraordinary conditions of the civil war of 49–45 (as evident in Caes. B Gall. 1.42 where he is forced to mount the Tenth Legion as a cavalry escort for his parlay with Ariovistus). The disappearance of Italian allied cavalry after the enfranchisement in the wake of the Social War points to a definite policy of not employing Roman cavalry. Men of equestrian rank still saw service as officers and there is evidence that the requirement of ten years’ service remained in effect, but service as an organized body of cavalry ceased.
The sources are silent about the reasons for this change. It has been suggested that the superiority of non-Roman cavalry was the driving force behind this transformation. However, the superiority of foreign cavalry had been clear since the Second Punic War. In fact, a strong argument has recently been made for the continued effectiveness of the Roman cavalry (McCall 2002: 13–52). Moreover, it seems likely that efficiency and effectiveness in a branch of service whose contribution was usually not decisive would not have been the crucial consideration. It is probable that the answer should be sought in social and political factors. The cavalry must have been as reluctant to serve in the long sequence of Spanish wars as the infantry. Further, certain developments point to a changed view of the nature of equestrian rank in this period. It is likely that it was in the mid- or late second century that admission to equestrian status came to depend on a fixed minimum census rating. The staffing of the extortion court under Gaius Gracchus by equestrians must have further attenuated the connection between cavalry service and equestrian status. Two further factors may be of significance: the prolonged and distant service now required of Roman armies and the lower prestige of military service in the wake of the acceptance of capite censi into the legions. A definitive answer is impossible, but the reappearance of legionary cavalry in the Imperial period supports the view that it was social rather than military factors that lay behind the change (see further Harmand 1967: 349–407).
Certain constants underlay Roman tactics. The practice of constructing fortified marching camps was of prime importance. They provided a secure base as evidenced by the fact that they were rarely assaulted successfully and could be used to tactical advantage in launching attacks on the enemy. A well-developed logistical system was also essential to army operations. Pre-modern armies could rarely support themselves completely by foraging in enemy territory. The logistical system of the Republican period allowed Roman armies to operate in areas such as the Syrian deserts where local resources could not have sustained them. By the beginning of the third century the Romans were able to field the largest army yet seen in Italy: approximately thirty-six thousand citizens and allies (see Erdkamp 1998 and Roth 1999). The consular armies of the mid-Republic normally consisted of two legions and an equal or greater number of allies. At Cynoscephalae Flaminius had an army of about twenty-six thousand Romans and allies, and at Pydna Paullus’s army totaled about the same number excluding Greek allies (Walbank 2: 167). The armies of the last century of the Republic were considerably larger. During his last years in Gaul Caesar was operating with a force of twelve legions, while at Pharsalus Pompey had eleven legions while Caesar fielded eight. These increases in army size significantly enlarged the tactical possibilities available to the Roman commander. The reserves of manpower available also allowed multiple armies to be fielded simultaneously. As early as the battle of Telamon in 225 the Romans were able to defeat a large army of Gauls by concentrically converging on the front and rear of the enemy (Polyb. 2.27–30).
Early Roman tactics were usually aggressive and designed to break the enemy formation by a frontal assault. This approach is most obvious at Cannae where the maniples were drawn up on a narrow front and with greater depth with the intention of breaking through the Carthaginian front (Polyb. 3.113.1). The disaster that ensued resulted from Hannibal’s ability to take advantage of Roman weakness in responding to attacks on the flanks and rear. This difficulty was compounded by the limitations of Roman cavalry until late in the war. The new tactics developed by Scipio Africanus were an answer to this problem. He was able to take advantage of the ability of the units of the manipular line to operate independently. At Ilipa Scipio was able to extend his line while it was in motion toward the enemy line and attack the Carthaginians on both flanks (Scullard 1970: 91–2). This tactic appears to have become standard maneuver. It reappears again the Roman victory at Cynoscephalae (Polyb. 18.26.1–3; Livy 33.9.8–9). Most battles in this period were no longer decided by a frontal attack but by flank attacks and ambushes (Sabin 1996: 59–79).
The first century witnessed a number of tactical developments. There was an increasing use of fortifications and entrenchments in the field as part of battlefield tactics. At Chaeronea in 86 Sulla countered the Mithridatic general Archelaus’s overwhelming numerical superiority by constructing a series of trenches and towers to protect his flanks (Plut. Sull. 18.1, 21.1; Frontin. Str. 2.3.17). Perhaps the most extensive use of such field fortifications was by Caesar during the civil war. At Dyrrachium he was able to place the much larger army of Pompey under siege using fortifications even if he failed in the end. At Uzita during the civil war in Africa both Caesar and Scipio used a series of field fortifications to gain tactical advantage (Caes. B. Afr. 49). The most spectacular use of such fortifications came during the siege of Alesia during the Gallic revolt of 52 (Caes. B Gall. 7.69, 72). In addition to the greater flexibility the cohort allowed in deployments on the battlefield, the other major development in the period is the improved handling of combined arms, especially marked in a greater use of both heavy and light cavalry.
The continued Roman reliance on heavy infantry as the decisive arm had its limitations and could end in disaster as it did for Crassus at Carrhae (see Garzetti 1944: 35–54, Goldsworthy 1996: 61–6). The most striking example comes from Caesar’s African campaign. At Ruspina Caesar’s force of 30 cohorts, 400 cavalry, and 150 archers was subjected to such a continuous and effective missile barrage by Labienus’s force of Numidian light-armed infantry and cavalry that Caesar’s infantry was forced out of formation and it suffered numerous casualties before Caesar dealt with the threat by having every other cohort face to the rear, move forward, and sweep the enemy from the field (Caes. B. Afr. 14–18). Dealing with a highly mobile enemy or a guerilla force remained a serious problem for slow-moving heavy infantry that continued into the Imperial period in campaigns in Germany and on the eastern frontier (note, for example, Caesar’s struggle with the Menapii and Morini who resorted to guerilla warfare, causing Caesar a number of problems [B Gall. 3.28, 6.5]).
Finally, the growth of the semi-professional army in the late Republic permitted the development of legions of veteran soldiers like Caesar’s famous Tenth that gave the commander a tactical advantage, which could be especially effective against formations of new recruits. In the final battle of the civil war at Munda Caesar’s right wing was held by a weakened Tenth whose reputation inspired such fear in the enemy that this psychological advantage played a crucial role in Caesar’s success (Caes. B Hisp. 31). There were many reasons for the development of a professional army in the Imperial period but one must have been the obvious effectiveness of well-trained veteran units on the battlefields of the civil wars.
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