Over time, the roles and equipment associated with the military system varied, but throughout Roman history, it always remained a disciplined and professional war machine. Soldiers trained like any other army from initial recruitment, doing weapons and armor instruction, formation marching, and tactical exercises. The normal training regimen consisted of gymnastics and swimming, to keep the soldiers in shape, fighting with armatura (wooden weapons) to learn and perfect combat techniques, and long marches with full equipment to strengthen endurance, background and accustom the soldiers to the harshness of a campaign, which used to be 30 km and repeated at least twice a month.[3]​.

The combat training exercises consisted of attacking a dummy, also made of wood, wearing full armor with a wooden gladius. They also fought among themselves with those same weapons. The legionaries were specially trained to launch thrusts from the protection of their large shields (scutums "Scutum (shield)")) since they were aware that a simple wound 3 or 4 cm deep could cause death; That's why they emphasized rapid stabbing techniques in vital areas or between gaps in armor. On Trajan's Column in Rome, you can see images from the time of Roman soldiers fighting and show them with their left foot and shield forward, while the right foot was held back and turned at a right angle outwards. This indicates a fighting style similar to boxing, where the shield is used to push and block the enemy while the sword, in the right hand, is used to deliver the knockout blow. Other training exercises taught the legionary to throw pilas, obey orders and adopt combat formations.[4]​.

A legionnaire generally carried about 27 kilos, including armor, weapons and various field equipment. For the soldier of the Late Republic and the Low Empire, the load consisted of armor, although the lorica segmentata (plate armor) had a greater weight than the lorica hamata (chain mail), the sword, a shield, two pila (one lighter and one heavier), the pugio or dagger and campaign rations for fifteen days. They also carried tools to dig and build a castra, or fortified legion base camp.

When the training was completed, the legionaries had to take an oath of loyalty to the SPQR (Senatus Populus Que Romanus) the Senate and the Roman people in times of the republic, or to the emperor in times of the Empire. Each soldier received a diploma and was sent to fight with his life for the glory and honor of Rome.[4]​.

Authority, control and structure

Once the soldier had completed his training, he was usually assigned to a legion, the basic mass combat unit. The Legion was subdivided into ten units called cohorts, roughly comparable to a modern infantry battalion. The cohorts, for their part, were divided into three maniples "Manipule (formation)"), which in turn were made up of two centuries of 80 men each. Each century was subdivided into ten confederations of eight men each. The contubernium was the basic combat unit of the Roman legion. The total strength of the entire legion was sixty centuries (four thousand eight hundred men). The first cohort of a legion was generally the elite unit, carrying the best equipment and the most experienced and skilled soldiers. Several united legions gave rise to a distinctive field force, an "army".[4]

The supreme command of each legion or army was exercised by a consul, proconsul or praetor. In cases of emergency in the Republican era, a dictator could also take command. A praetor or propraetor could only command a single legion, and never a consular army, which usually consisted of two Roman legions and an even number of allied troops. In the early republican period, dual authority was routine in an army, with two consuls alternating daily in command. In later centuries this was modified to benefit a single commander in chief of the army. Legates were officers of senatorial rank who assisted the supreme commander. Tribunes were generally young aristocrats who supervised administrative tasks such as the construction of camps. Centurions (roughly equivalent to a modern-day non-commissioned officer, but acting like modern captains in field operations) led cohorts, maniples, and centuries. Sometimes special operations forces such as engineers and armorers were used.[5]​.

Approach march

Once the legion was in the campaign, the march began. In general, the order of march depended a lot on the type of resistance that the troop commander thought he would encounter along the way, varying from the usual order that, for example, Josephus describes in his Jewish Wars") to the formation of an orbis, a special formation in which the legion was divided into its respective centuries that formed a square (see attached diagram;) In a case of medium danger, the approach to the battlefield was carried out in a formation of several Columns, which increased maneuverability. Normally, a well-armed vanguard corps preceded the main body. This corps included scouts, cavalry and other light troops. Each legion marched as a compact formation, accompanied by its own supply train. It acted as a rearguard, although the most recent units of the army could occupy this final echelon.

Construction of fortified camps.

Fielding legions typically built entire fortified camps, reinforced by palisades and a deep dike, which provided a base for storage of supplies, reorganization of troops, and defense. The Romans built a new camp every time they marched for a day (around 30 km).[6] The camps were destroyed the next day, before resuming their march. In addition to a military necessity, they represented religious symbolism. There were four access gates, connected by two main arteries, which crossed in the center of the camp, where the command tents were located. In the same way, a space was respected for the construction of an altar where religious services could be carried out. Everything was standardized, from the position of luggage, equipment and specific army units, to the duties of the officers who had to distribute sentries, pickets and orders for the next day's march. The construction of the camp took between 2 and 5 hours, during which part of the army worked, while the rest stood guard, depending on the tactical situation. No other army maintained this systematic method of camp construction for so long, even if the army rested for only one day.[7] Tents were set up inside. The general's occupied a privileged place.

Breaking up of camp and march

After a regimented breakfast at the indicated time, the trumpets sounded. The tents and cabins of the camp were dismantled and preparations for departure were made. The trumpet then sounded once again with the warning signal for the march. The mules "Mule (animal)") and wagons from the supply train were loaded and formed into units. The camp was then burned and destroyed to prevent it from being occupied by the enemy. The trumpets then sounded for the last time, asking the troops three times if they were ready and willing, to which they were expected to respond in unison, before beginning the march again.[8]​.

Intelligence

Good Roman commanders did not hesitate to use an intelligence service, particularly in siege situations or when pitched combat was looming. They collected information from spies, collaborators, ambassadors, special envoys and allies. Intercepted messages during the Second Punic War, for example, allowed the Romans to send two armies to intercept Hasdrubal Barca's Carthaginian army past the Alps, preventing him from reuniting with Hannibal. Commanders also kept alert to the situation in Rome, as enemies and political rivals could use an unsuccessful campaign to inflict a blow on an officer's career. During this initial phase, the usual field reconnaissance was also carried out, through patrols or test raids, which had the objective of discovering weak points on the enemy front, capturing prisoners and intimidating the inhabitants of the area.[9]​.

Logistics

Roman logistics proved to be the most effective in the ancient world, over the centuries: from the deployment of commercial agents to systematically purchase provisions during a campaign, to the construction of roads and supply warehouses, to the rental of maritime transport if troops had to travel over water. All equipment and heavy materials (tents, artillery, reserve weapons, whetstones, etc.) were packed and transported by animals and carts, while the troops carried individual backpacks, which included shovels and sticks to build the fortified camps. Like other armies, they took advantage of occasional opportunities, and the fields planted by those farmers unfortunate enough to be near the conflict area were often depleted to satisfy the army's needs. As with most armed forces, a troop of merchants, peddlers, prostitutes and other providers of various services followed them everywhere.[9]​.

Moral

If the potential battlefield was close, movement became slower and more careful. They could remain in the same place for several days studying the terrain and opposition, while the troops prepared mentally and physically for battle. Harangues, sacrifices to the gods and announcements of good omens could be carried out. Practical demonstrations could also take place to evaluate the enemy's reaction and raise the morale of the troops. Part of the army could leave the camp and deploy in line of battle before the enemy. If the enemy refused to offer battle, the commander could deliver a moral harangue to his men, contrasting the enemy's cowardice with the resolve of his own troops.[9]​.

Historian Adrian Goldsworthy points out that such pre-battle maneuvers were typical of ancient armies, as each side sought to gain the greatest possible advantage before combat broke out.[10] Several classical authors recount scenes of rival commanders negotiating or debating in general, as occurs in the famous conversation between Hannibal and Scipio Africanus prior to the battle of Zama. But whatever the reality of these encounters, or how flowery and ornate the words used in the harangues, the only encounter that had decisive importance was the battle.

Deployment for battle - The triple line or triplex acies

Pre-battle maneuvers allowed opposing commanders to gauge what the coming battle would be like, but the exact moment it broke out and its final outcome could be unpredictable. Skirmishes could get out of control, ending with both forces turning against each other. Political considerations, shortage of supplies or even rivalry between commanders in search of glory could also unleash a frontal attack, as occurred in the Battle of Trebia.[9]​.

Once the machinery had started rolling, the Roman infantry was generally deployed, as the main body, facing the enemy. During deployment in the Roman era, the maniples were commonly arranged in triplex acies") (triple order of battle): that is, in three levels, with the asteros in the first row (closest to the enemy), the princes in the second, and the veterans triarios in the third and last, in a kneeling position, so that they would not suddenly rush into the heat of battle, or, sometimes, even further back as a strategic reserve. When suffering a defeat, the first and second line (principes and "hastatos") retreated to the triarios to recompose the lines and carry out a counterattack or organized retreat. Since retreating to the triarios was a desperate measure, the phrase "go down to the triarios" (ad triarios rediisse) became a typical Roman phrase to refer to a desperate situation.[11]​.

With this system of triplex acies, contemporary Roman writers speak of maniples that adopted the checkerboard formation called quincunx when they were deployed for battle but before entering combat. In the first line, the stars left gaps equivalent in size to the area of ​​intersection between two maniples. The second line consisted of princes arranged similarly, lining up behind the gaps left by the first line. The third line did the same, which was placed between the gaps of the second line. The velites were arranged even further forward, in a continuous and loose line.

The Roman maneuver was complex, mixed with the dust of thousands of soldiers positioning themselves, and the shouting of officers moving between the lines trying to maintain order. Several thousand men were to be reorganized from a column formation to a line formation, with each unit taking its designated place, alongside light troops and cavalry. Fortified camps were arranged and organized to facilitate deployment. Initial placement could take some time, but once completed it represented a formidable fighting force, usually arranged in three lines with a front so extensive that it spanned more than a mile.[12]

The three-line deployment would be maintained over the centuries, although the Marian reforms gradually removed most distinctions based on age and class, standardized weaponry, and reorganized the legions into larger maneuver units such as cohorts. The total size of the army and length of military service were increased on a more permanent basis.[13]​.

Field combat and use of war machines

Once the deployment and initial skirmishes described above were completed, the main body of heavy infantry closed the gaps and attacked in unison. The first ranks normally threw their pila, and the following raised theirs over the heads of the first. If the throw of a javelin did not cause death or injury to an opponent, it was bent, making it unusable by its enemies, in the same way, if it penetrated a shield, bending would render it useless. After the launch, the soldiers drew their swords and launched themselves against the enemy. Special emphasis was placed on the use of the shield to provide maximum body coverage, while attacking the exposed part of the enemy's body. In the ensuing combat, Roman discipline, heavy shield, armor and training gave them a special advantage.

Some Roman infantry scholars maintain that the intense trauma and stress of hand-to-hand combat meant that combatants did not continually hit each other until one fell. Instead, there were short periods of frantic fighting. In moments of indecision, the contestants could separate a short distance to catch their breath, and accelerate forward again to resume the duel. Other soldiers behind would occupy the gap, facing new enemies or covering their companions. An individual warrior could therefore count on momentary relief, rather than an endless fight to the death or until incapacitated by serious wound. As the battle progressed, the physical and mental stress intensified. Endurance and willpower required a new charge, which carried with it a more frantic and desperate attack.[10] Eventually one side would begin to break, at which point the real massacre would begin.

Many Roman battles, especially during the Late Empire, featured preparatory fire from onagers and ballistae. These machines constituted a rudimentary body of artillery, they fired large arrows and stones at enemy formations (although many historians question the real effectiveness of these weapons). Following this barrier of projectiles, the Roman infantry advanced, in four lines, until they were thirty meters from the enemy. At that moment, they stopped, raised their stack and charged. If the first line was driven back by the enemy, a new line would quickly take its place. Often, this rapid sequence of deadly attacks, comparable to waves crashing against the shore, became the key to victory. Another common tactic was to provoke the enemy with preset changes and rapid missiles from the auxiliaires equites (auxiliary cavalry), which forced the rival army to pursue them. At this point they could be drawn into an ambush, where they would suffer counterattack by Roman cavalry and heavy infantry.

Advantages of the triple line

Some ancient sources such as Polybius seem to imply that legions could fight with gaps between their lines. However, most sources seem to admit that it was more common to form a compact line that offered a solid front. Various approaches have been taken to reconcile these ideas with ancient writings.[16] The advantages of gaps are obvious when a formation is underway: it can flow more comfortably around obstacles and improves maneuverability and control. Just as the Romans did in times of the Republic, they positioned baggage between the lines, so that the cargo was not easily captured and the army could quickly prepare for battle using it as cover. When the approach march ended, it would be very difficult to deploy an unscathed army on any terrain that was not completely level, without some sort of interval. Many ancient armies used gaps of some kind, including the Carthaginians, who retreated their skirmishers through these gaps before the main combat began. Even other more disorganized armies such as the Germans charged in differentiated groups with small gaps between the lines, instead of marching in a line.[17]​.

Fighting with discontinuities in the line is possible, therefore, as writers such as Polybius claim. What, according to those who argue that the quinqux formation was the main Roman phalanx array, made Roman tactics stand out was that its intervals were generally larger and systematically organized than those of other ancient armies. Each gap was covered by maniples or cohorts of later lines. Any major penetration would not simply occur: not only would it be hit laterally as it crossed the front line level, but it would be met by aggressive units advancing to cover the gap.[18] From a more general view, as the battle gained or lost intensity, new reinforcement units would be deployed through the intervals to relieve the front line soldiers, allowing for continued forward pressure.

A possible scenario for not using gaps is a limited space battlefield, such as a hill or gorge, where it is impossible to expand without limit. Another could be a set attack formation, such as the arrow discussed above, or an enveloping movement such as that at the Battle of Ilipa. Another could be a closing maneuver, when a solid line is built to make a final final push, as occurred in the Battle of Zama. In the clamor of battle it was also possible that, as units merged into a line, the board space would compress or even disappear, and a spectator would see a more or less solid line fighting the enemy. In Julius Caesar's armies, the use of the quincunx and its spaces seemed to have declined, and his legions were generally arranged in three compact lines as shown above, with four cohorts in front, and three in echelon fashion. This formation remained flexible, however, and continued to use gaps and adopt one or two lines according to tactical needs.[19]​.

Tactical orders after deployment

Whatever the type of deployment, the Roman army had marked flexibility, discipline and cohesion. Different formations were assumed according to different tactical situations.

• - Repelle equites ("repel horses") was the formation used to resist cavalry charges. The legionaries would assume a square formation, holding their stacks like spears in the gap between two shields, and would stand shoulder to shoulder.

• - At the command eicere pila ("throw pila"), the legionaries threw their pila at the enemy.

• - At the command cuneum formate ("form into an arrow"), the infantry formed an arrow to charge and break the enemy line. This formation was used as a shock tactic.

• - At the order contendite vestra sponte ("Confront your rival"), the legionaries assumed an aggressive disposition and attacked any rival who opposed them.

• - At the command orbem formate ("form in orb"), the legionaries assumed a circular formation, with the archers positioned in the center and behind the legionaries, providing covering fire. This tactic was mainly used when a small detachment had to hold a position and was surrounded by enemies.

• - At the order ciringite frontem, the legionaries maintained their position.

• - At the order frontem allargate ("widen the front"), the legionaries dispersed in a looser formation. This order was mainly used when they received a hail of arrows from the enemy during a charge.

• - At the order testudinem formate ("form in a turtle"), the legionaries adopted the formation in testudo or turtle "Turtle (formation)"). It moved slowly but was virtually impenetrable to enemy fire, and therefore very effective during sieges or when faced with heavy enemy fire. However, it was a weak formation for hand-to-hand combat, which is why it was only adopted when the enemy was far enough away so that the legionaries had time to recompose the formation before receiving the rival charge.

• - At the order Agmen formate ("form in square"), the legionaries were arranged in square, the most common formation of a century during battle.

Besieging cities

1. • In the first phase, the engineers (cohors fabrorum) built a fortified camp near the city, with walls of contravallatum") and watchtowers (turres extruere) to prevent enemy reinforcements from penetrating. Sometimes, ring walls were built around the perimeter of the city, as Julius Caesar did in the Battle of Alesia. They could also resort to mines "Mina (gallery)") under enemy walls.

2. • The second phase began with fire from onagers and ballistae, which was intended to cover the approach of the siege towers, full of legionaries ready to assault the city walls. Meanwhile, other cohorts approached the walls in a turtle formation, carrying ladders&action=edit&redlink=1 "Ladder (siege weapon) (not yet written)") and battering rams, intended to force the gates and scale the city walls.

3. • The third phase included the opening of the main gate of the city by the cohorts that had managed to penetrate the city or scale the walls, if the battering ram had not managed to break down the gates. Once the main gate was opened or a section of wall collapsed, the cavalry and the rest of the cohorts entered the city to finish off the remaining defenders.

Field fortifications

While powerful cities and forts, along with elaborate sieges to capture them, were common in the ancient world, the Romans were unique among armies of the time in making extensive use of field fortifications. Campaign after campaign, tremendous effort was spent digging - a job performed by the rank and file legionnaire. Their field equipment included a shovel, a dolabra or pickaxe, and a basket to deposit dirt. Some soldiers also carried a type of lawnmower. With this equipment they dug trenches, built walls and palisades and laid assault roads. Julius Caesar's operations in Alesia are well known. Caesar's camp surrounded the Gallic city, built with massive double walls that kept the defenders inside the city and prevented the arrival of reinforcements. A network of camps and forts was included in these works. The inner trench alone was 20 feet (6.1 m) deep and Caesar rechanneled a river to fill it with water. The ground was covered with iron wire in several places to deter the Gauls "Gauls (people)") from attempting an assault. Surprisingly for such an infantry-focused battle, Caesar relied on a strong cavalry contingent to counter the Gallic sorties. Ironically, many of these horsemen came from Germanic tribes with whom the triumvir had been reconciled shortly before.[22]​.

The power of Roman field fortifications has already been mentioned but, on other occasions, the Romans used trenches to secure their flanks against an enveloping movement if they were vastly outnumbered, as Caesar did during his operations in Belgian Gaul. In the region of Brittany, dikes and breakwaters were built to assault the Gallic coastal forts. Ditches, opposing trenches and other works were also used in the internal struggles between Caesar and Pompey, as the opponents maneuvered against each other in pitched battle.[22] In the later days of the Empire the extensive use of these fortifications declined, parallel to the use of heavy infantry. Either way, they represented a turning point in Rome's relentless rise as a hegemonic power in the ancient world.[23]

Roman infantry against Hellenic phalanx

Prior to the rise of Rome, the Hellenic phalanx represented the main infantry force in the Western world. She had become mistress of the battlefields from Sparta to Macedonia, successfully facing other non-European armies such as those of Persia or India. United in an armored mass and equipped with large sarissas from 12 to 21 feet (6.4 m) in length, the phalanx was a formidable force. Although sometimes adopted in a defensive configuration, the phalanx was most effective when moving forward, either in frontal combat or in oblique (echelon) order against an enemy flank, as attested by the victories of Alexander the Great and the Theban innovator "Thebes (Greece)") Epaminondas. Combined with other formations - light infantry and cavalry - it was, in Alexander's time, unbeatable.

However, the phalanx possessed key weaknesses. It had some maneuverability but once the crash occurred this was greatly reduced, particularly on rough terrain. Its approach in "dense mass" also made it a rigid formation. Compressed in the clamor of battle, his troops could only fight frontally. The diversity of troops gave the phalanx great flexibility, but this same flexibility became a double-edged sword: it relied on a mixture of units that was difficult to control and position. This included not only typical heavy infantry, cavalry, and light infantry; but also elite units, moderately armed groups as well as foreign contingents with their own fighting style and war elephant shock units.[24] Such "varied" forces presented problems of organization and command. If they were managed by a leader capable of organizing and combining them in combat, they were highly efficient. The campaigns of Alexander, Pyrrhus and Hannibal (a Hellenic-style combined arms formation) demonstrate this. Without permanent cohesion or with mediocre leaders, however, their effectiveness was uneven. The confrontation of Lucius Cornelius Scipio Asiaticus (brother of Africanus) against Antiochus III the Great in the Battle of Magnesia is an example of poor leadership of troops of various types and an example of poor cohesion is the provisional force assembled by Hannibal to fight at Zama. By the time the Romans faced the Hellenistic armies, the Greeks had stopped using flank protection troops and cavalry contingents and their combat system had degenerated into a mere clash of phalanxes. A formation of this style was the one that the Romans faced and defeated in the Battle of Cynoscephali "Battle of Cynoscephali (197 BC)").

The Romans themselves used certain aspects of the phalanx in their early legions, notably the last line of warriors in the classic triple line: the Triary spearmen. The long pikes of the triarians eventually disappeared and all legionaries were uniformly equipped with gladius, scutum "Scutum (shield)") and pilum; and deployed in the distinctive Roman manner that provided greater standardization and long-term cohesion against Hellenic-style formations.

The phalanxes that faced the legion were vulnerable to the more flexible Roman board deployment, which allowed each fighter a certain vital space in which to face the enemy hand-to-hand in close order. The maneuver system also allowed entire units to maneuver more widely, freed from the need to always remain packed into a rigid formation. The depth of the triple line deployment exerted constant, forward pressure. Most phalanxes used a huge line several ranges deep. This could be advantageous in the early phases of combat but, as more and more men became involved in the battle, the Roman modular formation allowed relief in pressure to be imposed over a wider line. As the combat lengthened and the battlefield was compressed, the phalanx was exhausted or immobilized in one position, while the Romans could not only maneuver but also carry out the last and definitive attacks.[12] The disposition of Hannibal's army in Zama seems to demonstrate this: the Carthaginians used a triple line arrangement, sacrificing their first two lines of dubious quality and keeping their veterans from Italy in reserve for the final encounter. The placement of Hannibal was highly recommended given his weakness in cavalry and infantry, but he did not think about a system of relief between the lines as the Romans did. Each line fought its particular battle and the last one was finally destroyed against the Roman anvil when it received the attack of Numidian horsemen in the rear.

The legions lived and trained together for a longer time and were more uniform and efficient (unlike Hannibal's final force), allowing mediocre commanders to maneuver and position their forces more or less efficiently. These qualities, among others, made them more than a rival for the phalanx when they faced each other in combat.[17]​.

Pyrrhus' Falangist system was a trial by fire for the Romans. Despite several defeats, they inflicted such losses on the king of Epirus that the expression "Pyrrhic victory" became synonymous with useless victory. As a skilled and experienced commander, Pyrrhus arranged a typical mixed phalanx system, including war elephant shock troops, light infantry formations (peltasts), elite units, and cavalry to support the heavy infantry. Using this method he was able to defeat the Romans on two occasions, with a third battle of doubtful outcome or resulting in little Roman tactical victory. The battles below illustrate the difficulties of fighting against phalanx forces. If properly led and disposed (it is therefore interesting to compare Pyrrhus with the disposition of Perseus fleeing in Pydna), they presented a credible alternative to the heavy legion. The Romans, in any case, learned from their own mistakes. In the battles after the Pyrrhic Wars, they showed themselves to be perfect experts on the Hellenic phalanx.

• - Battle of Heraclea.

• - Battle of Asculum "Battle of Asculum (279 BC)").

• - Battle of Benevento "Battle of Benevento (275 BC)").

In this battle, the Macedonian phalanx occupied a preferred position on high ground. However, not all of their units had managed to position themselves due to the skirmishes prior to the battle. In any case, the advance of their right wing made the Romans lose ground, who counterattacked on the right flank and managed to progress against a somewhat disorganized Macedonian left wing. The outcome remained in doubt, until an unknown tribune detached 20 maniples from the Roman line and carried out an enveloping movement against the Macedonian rearguard. This caused the enemy phalanx to collapse, ensuring victory for the Romans. The more flexible and effective organization of the legionaries had taken advantage of the weaknesses of the dense phalanx. Such triumphs ensured Roman hegemony in Greece and neighboring territories.

At Pydna, the contenders deployed on a relatively flat plain, and the Macedonians had reinforced the infantry with a significant contingent of cavalry. When push came to shove, the phalanx advanced in a perfect line against the Roman line, making some initial progress. However, the ground on which it had to advance was somewhat rugged, and the powerful phalanx formation lost its iron cohesion. The Romans absorbed the initial shock and counterattacked; Their more spaced formation and incessant pressure proved decisive in hand-to-hand combat on uneven terrain. In close combat, the sword and shield neutralized the sarissa, and the supplementary weapons of the Macedonians (lighter armor and a shorter sword, the classic xifos) placed them at an inferiority against the skillful and aggressive assault by the Roman heavy infantry. Perseus failed to efficiently deploy support troops to help the phalanx in its time of need. In fact, it seems that he fled as soon as the situation began to deteriorate without even using the cavalry. The contest was decided in less than two hours, with a complete defeat for the Kingdom of Macedonia.

The techniques of breaking through enemy phalanxes further illustrate the flexibility of the Roman army. When facing Phalangist armies, the legions used to deploy the velites in front of the enemy with the order contendite vestra sponte, to cause confusion and panic in the solid blocks of the phalanx. Meanwhile, the sagittarii or auxiliary archers "Archer (army)") were placed on the wings, in front of the cavalry, to cover the retreat of the velites. These archers were usually ordered to eiaculare flammas - shoot incendiary arrows - as occurred at the Battle of Benevento "Battle of Benevento (275 BC)"). The cohorts then advanced in arrow formation, supported by the fire of velites and auxiliaries, and charged the phalanx at a specific point, breaking their formation. They then flanked it using cavalry to ensure victory.

Tactical superiority of Hannibal's forces. Despite not being a classic phalanx force, Hannibal's army was made up of "mixed" contingents and elements common to Hellenic formations. At the end of his life, Hannibal is said to have named Pyrrhus as the past commander he most admired.[25] Curiously, Rome had dented Pyrrhus's forces before Hannibal's birth, and given their advantages in organization, discipline, and resource mobilization, the question arises as to why they were not more effective against the Carthaginians, who for most of their campaign in Italy suffered from numerical inferiority and a shortage of supplies from their homeland.

Hannibal's individual genius, the professionalism of the bulk of his troops (forged after several years of constant fighting first in Hispania and later in Italy), and his superior cavalry seem to have been the decisive factors. In combat after combat, Hannibal took advantage of the Romans' tendencies, particularly their desire to achieve a decisive victory. The tired and half-frozen legionaries who emerged from the Trebia to form on the opposite bank of the river are a clear example of how Hannibal manipulated the Romans to fight under his conditions, and in the place of his choice. The subsequent debacles at Lake Trasimene and Cannae reduced the proud Romans to avoiding battle, stalking the Punics from the Apennines, unwilling to risk a direct confrontation on the plain, where the enemy cavalry had a clear advantage.

Roman tactical sophistication and ability to adapt. But, although Hannibal's feat underlined that the Romans were far from invincible, it also showed their long-term virtues. They isolated and eventually bottlenecked the Carthaginians, accelerating their withdrawal from Italy through constant maneuvering. More importantly, it was the counterattack they began in Hispania and North Africa. They were eager to repay the humiliation suffered in Italy and remained on the defensive, but with incessant tenacity they attacked elsewhere, to finally destroy their enemies.[17]

They also learned from those enemies. The operations of Scipio Africanus consisted of an evolution of those that Hannibal had previously faced, showing a higher level of innovation, preparation and organization (compared to Sempronius in the Battle of the Trebia, for example). Scipio's contribution consisted in part of implementing more flexible maneuverability of tactical units, instead of the triple-line frontal attack advocated by his contemporaries. He also made more efficient use of cavalry, a weapon traditionally despised by the Romans. Their operations included pincer movements, consolidated battle lines, and "reverse Cannae" formations along with cavalry movements. Their victories in Hispania and the African campaign demonstrated a new sophistication in the way of Roman warfare, and reaffirmed the Roman ability to adapt, persist and overcome difficulties.[26] See the battles in detail:.

• - Battle of Baecula.

• - Battle of Ilipa.

• - Battle of Zama.

Roman infantry against Celtic, Iberian and Germanic peoples

The view of Rome's Gallic enemies has changed a lot. Several ancient historians consider them retrograde savages, unscrupulous destroyers of the civilization and glory of Rome. Some more modern views see them as a proto-nationalist light, ancient freedom fighters who resisted the armored foot of empire. Their bravery as worthy adversaries of Rome is often celebrated, as is the sculpture of the dying Galatian. The Gallic opposition was made up of a large number of diverse people and towns, ranging geographically from the valleys of France to the forests of the Rhine, passing through the mountains of Helvetia; in such a way that it is difficult to categorize them in a homogeneous way. The term "Gaul" has been used interchangeably to name the Celtic tribes of Britain and Caledonia, adding more diversity to the people grouped under this name. From a military point of view, however, they seemed to share several general characteristics: tribal politics with a relatively sparse and unelaborated state structure, light weaponry, unsophisticated tactics, poor organization, high degree of mobility, and inability to maintain combat power in their field forces for a long period.[27]

Although popular annals show the power of the legions and a group of charismatic commanders rapidly massacring large hordes of "savage barbarians"[28]​ (like the opening scene of the 2000 American film "Gladiator"), Rome suffered many embarrassing defeats at the hands of these tribal armies. In the Republican period (around 390-387 BC), the Cisalpine Gauls under the command of Breno "Brenus (4th century BC)"), sacked the city of Rome. Even after the Punic Wars were over, the Romans suffered heavy defeats against the Gauls such as the disaster of Noreia or the Battle of Arausio, both during the First Cimbrian War. In the early imperial period, Germanic war bands inflicted on Rome one of its most severe defeats, at the Battle of the Teutoburg Forest, which ended in the annihilation of three imperial legions, and marked the limit of Roman expansion in central Europe. It was these partly Germanic tribes (most had some familiarity with Rome and its culture, and had Romanized themselves) who brought about the final ruin of Roman military power in the west. Ironically, at the end of the Empire, most of the fighting occurred between forces composed mainly of barbarians, on both sides.[29]​.

Whatever their particular culture, the Celtic and Germanic tribes proved to be tough opponents, achieving several victories against their enemies. Some historians show that massive combat sometimes occurred in compact Falangist-style formations, overlapping shields, and using shield cover during sieges. In pitched battle, they occasionally used an arrow formation when attacking. Their best hope for success lay in four main factors:.

Roman infantry against enemy cavalry

The cavalry of their enemies represented one of the toughest challenges that the Roman infantry had to face. The combination of ranged attack and shock force, with great mobility, that the cavalry represented, took advantage of the main weaknesses of the legion: its deployment and relatively slow movements.

Defeat at the hands of powerful cavalry forces is a recursive element in Roman history, as illustrated by the campaigns of Hannibal, where Numidian and Celtiberian horsemen repeatedly overran the flanks of the Roman formation, delivering devastating blows to the wings and rear. Hannibal's great victory at Cannae (considered one of the greatest military catastrophes of the Roman era) consisted mainly of infantry combat, but the main role was played by cavalry, as in so many other victories.

An even more dramatic demonstration of Roman vulnerability is shown in the numerous wars against the Parthians and their heavy cavalry. The Parthians and their successors used large numbers of lightly armored cavalry archers with fast horses to harass and skirmish with the enemy, and delivered the final blow with armored spearmen known as "cataphracts." Both types of troops used powerful composite bows that fired arrows powerful enough to pierce Roman armor. The cataphracts then served as shock troops, charging with the force of a battering ram against the Roman ranks, once they had "softened" after the swarms of arrows. At the same time, they used a "scorched earth" strategy against the Romans, refusing large pitched battles, while drawing them further and further into unfavorable terrain, where their supplies were scarce and they had no safe line of retreat. The devastating defeat of the Roman infantry at Carras made the Parthian cavalry seem invincible.

Alexander the Great had already used this method during his campaigns. He attacked the Asian horsemen with detachments of light infantry, skirmishers and archers, and drove them from the battlefield with charges of his heavy cavalry. The Roman variant used this same "combined arms" approach, giving greater importance to the role of infantry. In later times, however, the importance and numbers of cavalry grew: in particular, the eastern half of the Empire would rely almost entirely on its cavalry forces.

Even in the noon of the foot soldier, large units of light skirmishers were deployed with the legions, to intercept the fast horsemen at a reasonable distance. The Roman cavalry played an important role, consisting of "screening" the main force, intercepting entire detachments of marauding horsemen. Using these supports, the heavy legions were able to come into contact with enemy cavalry.

Modifications by Ventidius. The Roman general Publius Ventidius Basus took charge of the readjustment of the legion to face the mounted enemies, specifically the Parthians. Sent by Mark Antony to Syria to stop the Parthian invasion of 40 BC. C., he defeated the Asians up to three times, where he killed as many generals of Parthia.[44]​ The main tactical modifications contributed by Ventidio were:[44]​.

Assessment of the Roman infantry

Several of Rome's military campaigns display either sustained invincibility or dazzling genius. Roman performance in many battles was either unimpressive or disastrous. When it came to ambushes (such as the Teutoburg Forest debacle), the Roman forces seemed prone to receiving successive charges, as occurred centuries before at Lake Trasimeno. Throughout the republic, they were defeated by generals such as Pyrrhus, Hannibal and many other enemy leaders. They also suffered important defeats against mounted enemies, such as the Parthians or Sassanids. And yet, over time, the Romans not only recovered from these defeats, but for the most part finished off or neutralized their enemies. How was it possible that they achieved it in the face of such a variety of enemies, in different times and places, more numerous, better led or more prepared?

Some elements that made the Romans an effective military force, at a tactical and strategic level, were:

They were able to copy and adapt the weapons and methods of their enemies efficiently. Some weapons, such as the gladius hispanicus were adopted by the legionaries if they were more effective than their own weapons. In other cases, it was possible for the Romans to invite especially tough or dangerous enemies to serve in the Roman army, as auxiliaries. In the naval sphere, the Romans followed several of the methods used by the infantry, abandoning their old designs, copying and evolving the Punic trireme (using the corvus "Corvus (weapon)") among other structural details), converting naval battles into infantry combat on deck.[49]​.

Roman organization was more flexible than that of most of its rivals. Not only was it superior to that of the often massed and uncoordinated tribal peoples who comprised the bulk of its enemies; In contrast, Roman heavy infantry was capable of adopting different formations and combat methods depending on the situation. From the tortoise formation "Turtle (formation)") in sieges, to the infantry square used against mounted enemies, through combined units to confront the Iberian guerrilla. The triple line or board patterns also allowed changing from one formation to another in combat, and the hierarchical organization of the units allowed officers to do their jobs with high effectiveness. They were able to improvise ingenious tactics, as Scipio did at Zama, leaving wide gaps between the lines to allow the elephants to pass: placing velites on both sides to shoot them and push them back towards the Carthaginian lines, and then closing the gaps into a single line that faced the Italian veterans of Hannibal's army.

Discipline, organization and logistical systematization maintained combat effectiveness for long periods. It is worth highlighting the system of fortified camps or , which allowed the army a defense worthy of the best permanent fort, rest and resupply for battle. Roman logistics was capable of maintaining combat power over long periods, from routine resupply and storage of supplies, to the construction of military roads, state arsenals, and weapons factories. In the naval war, periodic convoys were organized, a key element in the defeat of Carthage. The death of a leader, as a general rule, did not appreciably demoralize the troops, as a new leader emerged and continued the fight. In the defeat inflicted by Hannibal along the River Trebia, 10,000 Romans escaped the disaster to safety, maintaining order and cohesion in retreat, as the line around them fled in disarray. This testifies to their tactical organization and discipline.[49]​.

Infantry decline: controversies

Every history of the Roman infantry confronts the factors that led to its decline. Such decline, of course, is associated with the decline of the economy, Roman society and political scene. Despite this, it is noteworthy that the final disappearance of Rome was the consequence of a military defeat, no matter how plausible the plethora of theories put forward by scholars and historians are, ranging from reduced tax bases, class struggle, or decline of its leaders.[50] Two of the main factors considered by military scholars will be discussed here: barbarization of the infantry and evolution to a "mobile defense" strategy. There are a number of controversies and conflicting opinions in this area.

To combat the increasingly frequent raids and attacks of their border enemies, the legions changed from a slow and heavy force to an increasingly lighter troop, in addition to introducing cavalry elements on an increasingly larger scale.

This meant that the new infantry lost the incredible attack power that the early legions had, which meant that, although the probability of entering battle was much greater, they had less chance of winning it. The smaller size of this new legion also influenced this fact.

The Roman horsemen, although fast, were very weak compared to the invading Huns, Goths, Vandals and Sassanids. This ineffectiveness was demonstrated at Cannae and later at Adrianople: in both cases, the cavalry was completely destroyed by a much superior mounted enemy better trained for this type of combat.

"Barbarization" is a recurring theme in many works on Rome (see Gibbon, Mommsen, Delbrück, and others). In essence, it is argued that the increasing barbarization of the heavy legions weakened the quality of weapons, training, morale and long-term military effectiveness. The weapons changes described above are just one example.[51]​.

It can be argued that the use of barbarian personnel was not a new fact. Although this is true, said use was clearly defined in the "Roman style": it was the barbarian personnel who had to adapt to Roman standards and organization, and not the other way around. In the decline of the Empire, however, this was not the case. Practices such as allowing the establishment of large contingents of barbarian population within the boundaries of the Empire, the laxity of the quality of Roman citizenship, increasing use of foreign troops and relaxation or elimination of the severe traditional discipline, its organization and control, contributed to the decline of heavy infantry.

The foederati emplacements, for example, consisted of large barbarian contingents settled in Roman territory, with their own organization and under their own leaders. Such groups showed a tendency to ignore the "Roman way" of organization, training, logistics, etc., in favor of their own ideas, practices and methods. These emplacements may have brought political peace in the short term for the Roman elites, but in the long term their effect was negative, breaking the traditional advantages of heavy infantry in terms of battle training, discipline and field deployment. Likewise, since the barbarians received equal or better treatment with much less effort, the "old guard" declined and received no incentives to perpetuate the old customs. Indeed, these contingents of "allies" often turned against the Romans, devastating and plundering wide areas and even attacking imperial army formations.

Twilight of the Elite Infantry

There are many other facets to the controversy over the end of the old legions, but whatever the school of thought, all agree that the traditional values ​​and weaponry of the old heavy legion fell into decline. Vegetius, a 19th-century writer, in what is one of the most influential military works in the Western world, highlighted this decline as part of an integrated team between cavalry and light infantry. In recent years, this formula that had brought so much success began to fade away. Caught between the growth of more lightly armed and disorganized infantry, and the increasingly numerous cavalry formations within the mobile forces, the "heavies" as a dominant force withered. This did not mean that they completely disappeared, but their massive recruitment, training, organization and deployment as an essential part of the Roman military system was greatly affected. Ironically, in the last battles of the Western Empire, the defeats suffered were inflicted by infantry forces (many fighting on the ground).

Historian Arther Ferrill notes that even towards the end, some of the old infantry formations were still in use. Such groups were becoming less and less effective, lacking the severity in order and discipline, instruction and organization of the old days. At the Battle of Chalons (c. 451), Attila the Hun harangued his troops, mocking the once-respected Roman infantry, claiming that they did nothing more than huddle behind a screen of shields in close formation. He ordered his troops to ignore them and attack the powerful Alans and Visigoths instead. It was a sad commentary on the force that had once dominated Europe, the Mediterranean and most of the Middle East. Although it is true that at Chalons the Roman infantry contributed to the victory by capturing high ground in the middle of the battlefield, their days had already passed, it was time for the massive levies of foederati barbarians.[54]​.

Grades

• - Portal:Ancient Rome. Content related to Ancient Rome.

• - Wikimedia Commons hosts a multimedia category on Roman Infantry Tactics.

• - Wikisource contains original works by or about Roman Infantry Tactics.

• - The exercitus hispanicus from Augustus to Vespasian; text in PDF.

• - Flavius ​​Arriano: Tactics.

• French text, with comments in the same language, on the site of Philippe Remacle (1944 - 2011).

• - Flavio Arriano: Mobilization plan against the Alans.

• - Greek text, with electronic index, in the Perseus Project. Using the active tag "load" at the top right, you get help in English with the Greek vocabulary in the text.

Over time, the roles and equipment associated with the military system varied, but throughout Roman history, it always remained a disciplined and professional war machine. Soldiers trained like any other army from initial recruitment, doing weapons and armor instruction, formation marching, and tactical exercises. The normal training regimen consisted of gymnastics and swimming, to keep the soldiers in shape, fighting with armatura (wooden weapons) to learn and perfect combat techniques, and long marches with full equipment to strengthen endurance, background and accustom the soldiers to the harshness of a campaign, which used to be 30 km and repeated at least twice a month.[3]​.

The combat training exercises consisted of attacking a dummy, also made of wood, wearing full armor with a wooden gladius. They also fought among themselves with those same weapons. The legionaries were specially trained to launch thrusts from the protection of their large shields (scutums "Scutum (shield)")) since they were aware that a simple wound 3 or 4 cm deep could cause death; That's why they emphasized rapid stabbing techniques in vital areas or between gaps in armor. On Trajan's Column in Rome, you can see images from the time of Roman soldiers fighting and show them with their left foot and shield forward, while the right foot was held back and turned at a right angle outwards. This indicates a fighting style similar to boxing, where the shield is used to push and block the enemy while the sword, in the right hand, is used to deliver the knockout blow. Other training exercises taught the legionary to throw pilas, obey orders and adopt combat formations.[4]​.

A legionnaire generally carried about 27 kilos, including armor, weapons and various field equipment. For the soldier of the Late Republic and the Low Empire, the load consisted of armor, although the lorica segmentata (plate armor) had a greater weight than the lorica hamata (chain mail), the sword, a shield, two pila (one lighter and one heavier), the pugio or dagger and campaign rations for fifteen days. They also carried tools to dig and build a castra, or fortified legion base camp.

When the training was completed, the legionaries had to take an oath of loyalty to the SPQR (Senatus Populus Que Romanus) the Senate and the Roman people in times of the republic, or to the emperor in times of the Empire. Each soldier received a diploma and was sent to fight with his life for the glory and honor of Rome.[4]​.

Authority, control and structure

Once the soldier had completed his training, he was usually assigned to a legion, the basic mass combat unit. The Legion was subdivided into ten units called cohorts, roughly comparable to a modern infantry battalion. The cohorts, for their part, were divided into three maniples "Manipule (formation)"), which in turn were made up of two centuries of 80 men each. Each century was subdivided into ten confederations of eight men each. The contubernium was the basic combat unit of the Roman legion. The total strength of the entire legion was sixty centuries (four thousand eight hundred men). The first cohort of a legion was generally the elite unit, carrying the best equipment and the most experienced and skilled soldiers. Several united legions gave rise to a distinctive field force, an "army".[4]

The supreme command of each legion or army was exercised by a consul, proconsul or praetor. In cases of emergency in the Republican era, a dictator could also take command. A praetor or propraetor could only command a single legion, and never a consular army, which usually consisted of two Roman legions and an even number of allied troops. In the early republican period, dual authority was routine in an army, with two consuls alternating daily in command. In later centuries this was modified to benefit a single commander in chief of the army. Legates were officers of senatorial rank who assisted the supreme commander. Tribunes were generally young aristocrats who supervised administrative tasks such as the construction of camps. Centurions (roughly equivalent to a modern-day non-commissioned officer, but acting like modern captains in field operations) led cohorts, maniples, and centuries. Sometimes special operations forces such as engineers and armorers were used.[5]​.

Approach march

Once the legion was in the campaign, the march began. In general, the order of march depended a lot on the type of resistance that the troop commander thought he would encounter along the way, varying from the usual order that, for example, Josephus describes in his Jewish Wars") to the formation of an orbis, a special formation in which the legion was divided into its respective centuries that formed a square (see attached diagram;) In a case of medium danger, the approach to the battlefield was carried out in a formation of several Columns, which increased maneuverability. Normally, a well-armed vanguard corps preceded the main body. This corps included scouts, cavalry and other light troops. Each legion marched as a compact formation, accompanied by its own supply train. It acted as a rearguard, although the most recent units of the army could occupy this final echelon.

Construction of fortified camps.

Fielding legions typically built entire fortified camps, reinforced by palisades and a deep dike, which provided a base for storage of supplies, reorganization of troops, and defense. The Romans built a new camp every time they marched for a day (around 30 km).[6] The camps were destroyed the next day, before resuming their march. In addition to a military necessity, they represented religious symbolism. There were four access gates, connected by two main arteries, which crossed in the center of the camp, where the command tents were located. In the same way, a space was respected for the construction of an altar where religious services could be carried out. Everything was standardized, from the position of luggage, equipment and specific army units, to the duties of the officers who had to distribute sentries, pickets and orders for the next day's march. The construction of the camp took between 2 and 5 hours, during which part of the army worked, while the rest stood guard, depending on the tactical situation. No other army maintained this systematic method of camp construction for so long, even if the army rested for only one day.[7] Tents were set up inside. The general's occupied a privileged place.

Breaking up of camp and march

After a regimented breakfast at the indicated time, the trumpets sounded. The tents and cabins of the camp were dismantled and preparations for departure were made. The trumpet then sounded once again with the warning signal for the march. The mules "Mule (animal)") and wagons from the supply train were loaded and formed into units. The camp was then burned and destroyed to prevent it from being occupied by the enemy. The trumpets then sounded for the last time, asking the troops three times if they were ready and willing, to which they were expected to respond in unison, before beginning the march again.[8]​.

Intelligence

Good Roman commanders did not hesitate to use an intelligence service, particularly in siege situations or when pitched combat was looming. They collected information from spies, collaborators, ambassadors, special envoys and allies. Intercepted messages during the Second Punic War, for example, allowed the Romans to send two armies to intercept Hasdrubal Barca's Carthaginian army past the Alps, preventing him from reuniting with Hannibal. Commanders also kept alert to the situation in Rome, as enemies and political rivals could use an unsuccessful campaign to inflict a blow on an officer's career. During this initial phase, the usual field reconnaissance was also carried out, through patrols or test raids, which had the objective of discovering weak points on the enemy front, capturing prisoners and intimidating the inhabitants of the area.[9]​.

Logistics

Roman logistics proved to be the most effective in the ancient world, over the centuries: from the deployment of commercial agents to systematically purchase provisions during a campaign, to the construction of roads and supply warehouses, to the rental of maritime transport if troops had to travel over water. All equipment and heavy materials (tents, artillery, reserve weapons, whetstones, etc.) were packed and transported by animals and carts, while the troops carried individual backpacks, which included shovels and sticks to build the fortified camps. Like other armies, they took advantage of occasional opportunities, and the fields planted by those farmers unfortunate enough to be near the conflict area were often depleted to satisfy the army's needs. As with most armed forces, a troop of merchants, peddlers, prostitutes and other providers of various services followed them everywhere.[9]​.

Moral

If the potential battlefield was close, movement became slower and more careful. They could remain in the same place for several days studying the terrain and opposition, while the troops prepared mentally and physically for battle. Harangues, sacrifices to the gods and announcements of good omens could be carried out. Practical demonstrations could also take place to evaluate the enemy's reaction and raise the morale of the troops. Part of the army could leave the camp and deploy in line of battle before the enemy. If the enemy refused to offer battle, the commander could deliver a moral harangue to his men, contrasting the enemy's cowardice with the resolve of his own troops.[9]​.

Historian Adrian Goldsworthy points out that such pre-battle maneuvers were typical of ancient armies, as each side sought to gain the greatest possible advantage before combat broke out.[10] Several classical authors recount scenes of rival commanders negotiating or debating in general, as occurs in the famous conversation between Hannibal and Scipio Africanus prior to the battle of Zama. But whatever the reality of these encounters, or how flowery and ornate the words used in the harangues, the only encounter that had decisive importance was the battle.

Deployment for battle - The triple line or triplex acies

Pre-battle maneuvers allowed opposing commanders to gauge what the coming battle would be like, but the exact moment it broke out and its final outcome could be unpredictable. Skirmishes could get out of control, ending with both forces turning against each other. Political considerations, shortage of supplies or even rivalry between commanders in search of glory could also unleash a frontal attack, as occurred in the Battle of Trebia.[9]​.

Once the machinery had started rolling, the Roman infantry was generally deployed, as the main body, facing the enemy. During deployment in the Roman era, the maniples were commonly arranged in triplex acies") (triple order of battle): that is, in three levels, with the asteros in the first row (closest to the enemy), the princes in the second, and the veterans triarios in the third and last, in a kneeling position, so that they would not suddenly rush into the heat of battle, or, sometimes, even further back as a strategic reserve. When suffering a defeat, the first and second line (principes and "hastatos") retreated to the triarios to recompose the lines and carry out a counterattack or organized retreat. Since retreating to the triarios was a desperate measure, the phrase "go down to the triarios" (ad triarios rediisse) became a typical Roman phrase to refer to a desperate situation.[11]​.

With this system of triplex acies, contemporary Roman writers speak of maniples that adopted the checkerboard formation called quincunx when they were deployed for battle but before entering combat. In the first line, the stars left gaps equivalent in size to the area of ​​intersection between two maniples. The second line consisted of princes arranged similarly, lining up behind the gaps left by the first line. The third line did the same, which was placed between the gaps of the second line. The velites were arranged even further forward, in a continuous and loose line.

The Roman maneuver was complex, mixed with the dust of thousands of soldiers positioning themselves, and the shouting of officers moving between the lines trying to maintain order. Several thousand men were to be reorganized from a column formation to a line formation, with each unit taking its designated place, alongside light troops and cavalry. Fortified camps were arranged and organized to facilitate deployment. Initial placement could take some time, but once completed it represented a formidable fighting force, usually arranged in three lines with a front so extensive that it spanned more than a mile.[12]

The three-line deployment would be maintained over the centuries, although the Marian reforms gradually removed most distinctions based on age and class, standardized weaponry, and reorganized the legions into larger maneuver units such as cohorts. The total size of the army and length of military service were increased on a more permanent basis.[13]​.

Field combat and use of war machines

Once the deployment and initial skirmishes described above were completed, the main body of heavy infantry closed the gaps and attacked in unison. The first ranks normally threw their pila, and the following raised theirs over the heads of the first. If the throw of a javelin did not cause death or injury to an opponent, it was bent, making it unusable by its enemies, in the same way, if it penetrated a shield, bending would render it useless. After the launch, the soldiers drew their swords and launched themselves against the enemy. Special emphasis was placed on the use of the shield to provide maximum body coverage, while attacking the exposed part of the enemy's body. In the ensuing combat, Roman discipline, heavy shield, armor and training gave them a special advantage.

Some Roman infantry scholars maintain that the intense trauma and stress of hand-to-hand combat meant that combatants did not continually hit each other until one fell. Instead, there were short periods of frantic fighting. In moments of indecision, the contestants could separate a short distance to catch their breath, and accelerate forward again to resume the duel. Other soldiers behind would occupy the gap, facing new enemies or covering their companions. An individual warrior could therefore count on momentary relief, rather than an endless fight to the death or until incapacitated by serious wound. As the battle progressed, the physical and mental stress intensified. Endurance and willpower required a new charge, which carried with it a more frantic and desperate attack.[10] Eventually one side would begin to break, at which point the real massacre would begin.

Many Roman battles, especially during the Late Empire, featured preparatory fire from onagers and ballistae. These machines constituted a rudimentary body of artillery, they fired large arrows and stones at enemy formations (although many historians question the real effectiveness of these weapons). Following this barrier of projectiles, the Roman infantry advanced, in four lines, until they were thirty meters from the enemy. At that moment, they stopped, raised their stack and charged. If the first line was driven back by the enemy, a new line would quickly take its place. Often, this rapid sequence of deadly attacks, comparable to waves crashing against the shore, became the key to victory. Another common tactic was to provoke the enemy with preset changes and rapid missiles from the auxiliaires equites (auxiliary cavalry), which forced the rival army to pursue them. At this point they could be drawn into an ambush, where they would suffer counterattack by Roman cavalry and heavy infantry.

Advantages of the triple line

Some ancient sources such as Polybius seem to imply that legions could fight with gaps between their lines. However, most sources seem to admit that it was more common to form a compact line that offered a solid front. Various approaches have been taken to reconcile these ideas with ancient writings.[16] The advantages of gaps are obvious when a formation is underway: it can flow more comfortably around obstacles and improves maneuverability and control. Just as the Romans did in times of the Republic, they positioned baggage between the lines, so that the cargo was not easily captured and the army could quickly prepare for battle using it as cover. When the approach march ended, it would be very difficult to deploy an unscathed army on any terrain that was not completely level, without some sort of interval. Many ancient armies used gaps of some kind, including the Carthaginians, who retreated their skirmishers through these gaps before the main combat began. Even other more disorganized armies such as the Germans charged in differentiated groups with small gaps between the lines, instead of marching in a line.[17]​.

Fighting with discontinuities in the line is possible, therefore, as writers such as Polybius claim. What, according to those who argue that the quinqux formation was the main Roman phalanx array, made Roman tactics stand out was that its intervals were generally larger and systematically organized than those of other ancient armies. Each gap was covered by maniples or cohorts of later lines. Any major penetration would not simply occur: not only would it be hit laterally as it crossed the front line level, but it would be met by aggressive units advancing to cover the gap.[18] From a more general view, as the battle gained or lost intensity, new reinforcement units would be deployed through the intervals to relieve the front line soldiers, allowing for continued forward pressure.

A possible scenario for not using gaps is a limited space battlefield, such as a hill or gorge, where it is impossible to expand without limit. Another could be a set attack formation, such as the arrow discussed above, or an enveloping movement such as that at the Battle of Ilipa. Another could be a closing maneuver, when a solid line is built to make a final final push, as occurred in the Battle of Zama. In the clamor of battle it was also possible that, as units merged into a line, the board space would compress or even disappear, and a spectator would see a more or less solid line fighting the enemy. In Julius Caesar's armies, the use of the quincunx and its spaces seemed to have declined, and his legions were generally arranged in three compact lines as shown above, with four cohorts in front, and three in echelon fashion. This formation remained flexible, however, and continued to use gaps and adopt one or two lines according to tactical needs.[19]​.

Tactical orders after deployment

Whatever the type of deployment, the Roman army had marked flexibility, discipline and cohesion. Different formations were assumed according to different tactical situations.

• - Repelle equites ("repel horses") was the formation used to resist cavalry charges. The legionaries would assume a square formation, holding their stacks like spears in the gap between two shields, and would stand shoulder to shoulder.

• - At the command eicere pila ("throw pila"), the legionaries threw their pila at the enemy.

• - At the command cuneum formate ("form into an arrow"), the infantry formed an arrow to charge and break the enemy line. This formation was used as a shock tactic.

• - At the order contendite vestra sponte ("Confront your rival"), the legionaries assumed an aggressive disposition and attacked any rival who opposed them.

• - At the command orbem formate ("form in orb"), the legionaries assumed a circular formation, with the archers positioned in the center and behind the legionaries, providing covering fire. This tactic was mainly used when a small detachment had to hold a position and was surrounded by enemies.

• - At the order ciringite frontem, the legionaries maintained their position.

• - At the order frontem allargate ("widen the front"), the legionaries dispersed in a looser formation. This order was mainly used when they received a hail of arrows from the enemy during a charge.

• - At the order testudinem formate ("form in a turtle"), the legionaries adopted the formation in testudo or turtle "Turtle (formation)"). It moved slowly but was virtually impenetrable to enemy fire, and therefore very effective during sieges or when faced with heavy enemy fire. However, it was a weak formation for hand-to-hand combat, which is why it was only adopted when the enemy was far enough away so that the legionaries had time to recompose the formation before receiving the rival charge.

• - At the order Agmen formate ("form in square"), the legionaries were arranged in square, the most common formation of a century during battle.

Besieging cities

1. • In the first phase, the engineers (cohors fabrorum) built a fortified camp near the city, with walls of contravallatum") and watchtowers (turres extruere) to prevent enemy reinforcements from penetrating. Sometimes, ring walls were built around the perimeter of the city, as Julius Caesar did in the Battle of Alesia. They could also resort to mines "Mina (gallery)") under enemy walls.

2. • The second phase began with fire from onagers and ballistae, which was intended to cover the approach of the siege towers, full of legionaries ready to assault the city walls. Meanwhile, other cohorts approached the walls in a turtle formation, carrying ladders&action=edit&redlink=1 "Ladder (siege weapon) (not yet written)") and battering rams, intended to force the gates and scale the city walls.

3. • The third phase included the opening of the main gate of the city by the cohorts that had managed to penetrate the city or scale the walls, if the battering ram had not managed to break down the gates. Once the main gate was opened or a section of wall collapsed, the cavalry and the rest of the cohorts entered the city to finish off the remaining defenders.

Field fortifications

While powerful cities and forts, along with elaborate sieges to capture them, were common in the ancient world, the Romans were unique among armies of the time in making extensive use of field fortifications. Campaign after campaign, tremendous effort was spent digging - a job performed by the rank and file legionnaire. Their field equipment included a shovel, a dolabra or pickaxe, and a basket to deposit dirt. Some soldiers also carried a type of lawnmower. With this equipment they dug trenches, built walls and palisades and laid assault roads. Julius Caesar's operations in Alesia are well known. Caesar's camp surrounded the Gallic city, built with massive double walls that kept the defenders inside the city and prevented the arrival of reinforcements. A network of camps and forts was included in these works. The inner trench alone was 20 feet (6.1 m) deep and Caesar rechanneled a river to fill it with water. The ground was covered with iron wire in several places to deter the Gauls "Gauls (people)") from attempting an assault. Surprisingly for such an infantry-focused battle, Caesar relied on a strong cavalry contingent to counter the Gallic sorties. Ironically, many of these horsemen came from Germanic tribes with whom the triumvir had been reconciled shortly before.[22]​.

The power of Roman field fortifications has already been mentioned but, on other occasions, the Romans used trenches to secure their flanks against an enveloping movement if they were vastly outnumbered, as Caesar did during his operations in Belgian Gaul. In the region of Brittany, dikes and breakwaters were built to assault the Gallic coastal forts. Ditches, opposing trenches and other works were also used in the internal struggles between Caesar and Pompey, as the opponents maneuvered against each other in pitched battle.[22] In the later days of the Empire the extensive use of these fortifications declined, parallel to the use of heavy infantry. Either way, they represented a turning point in Rome's relentless rise as a hegemonic power in the ancient world.[23]

Roman infantry against Hellenic phalanx

Prior to the rise of Rome, the Hellenic phalanx represented the main infantry force in the Western world. She had become mistress of the battlefields from Sparta to Macedonia, successfully facing other non-European armies such as those of Persia or India. United in an armored mass and equipped with large sarissas from 12 to 21 feet (6.4 m) in length, the phalanx was a formidable force. Although sometimes adopted in a defensive configuration, the phalanx was most effective when moving forward, either in frontal combat or in oblique (echelon) order against an enemy flank, as attested by the victories of Alexander the Great and the Theban innovator "Thebes (Greece)") Epaminondas. Combined with other formations - light infantry and cavalry - it was, in Alexander's time, unbeatable.

However, the phalanx possessed key weaknesses. It had some maneuverability but once the crash occurred this was greatly reduced, particularly on rough terrain. Its approach in "dense mass" also made it a rigid formation. Compressed in the clamor of battle, his troops could only fight frontally. The diversity of troops gave the phalanx great flexibility, but this same flexibility became a double-edged sword: it relied on a mixture of units that was difficult to control and position. This included not only typical heavy infantry, cavalry, and light infantry; but also elite units, moderately armed groups as well as foreign contingents with their own fighting style and war elephant shock units.[24] Such "varied" forces presented problems of organization and command. If they were managed by a leader capable of organizing and combining them in combat, they were highly efficient. The campaigns of Alexander, Pyrrhus and Hannibal (a Hellenic-style combined arms formation) demonstrate this. Without permanent cohesion or with mediocre leaders, however, their effectiveness was uneven. The confrontation of Lucius Cornelius Scipio Asiaticus (brother of Africanus) against Antiochus III the Great in the Battle of Magnesia is an example of poor leadership of troops of various types and an example of poor cohesion is the provisional force assembled by Hannibal to fight at Zama. By the time the Romans faced the Hellenistic armies, the Greeks had stopped using flank protection troops and cavalry contingents and their combat system had degenerated into a mere clash of phalanxes. A formation of this style was the one that the Romans faced and defeated in the Battle of Cynoscephali "Battle of Cynoscephali (197 BC)").

The Romans themselves used certain aspects of the phalanx in their early legions, notably the last line of warriors in the classic triple line: the Triary spearmen. The long pikes of the triarians eventually disappeared and all legionaries were uniformly equipped with gladius, scutum "Scutum (shield)") and pilum; and deployed in the distinctive Roman manner that provided greater standardization and long-term cohesion against Hellenic-style formations.

The phalanxes that faced the legion were vulnerable to the more flexible Roman board deployment, which allowed each fighter a certain vital space in which to face the enemy hand-to-hand in close order. The maneuver system also allowed entire units to maneuver more widely, freed from the need to always remain packed into a rigid formation. The depth of the triple line deployment exerted constant, forward pressure. Most phalanxes used a huge line several ranges deep. This could be advantageous in the early phases of combat but, as more and more men became involved in the battle, the Roman modular formation allowed relief in pressure to be imposed over a wider line. As the combat lengthened and the battlefield was compressed, the phalanx was exhausted or immobilized in one position, while the Romans could not only maneuver but also carry out the last and definitive attacks.[12] The disposition of Hannibal's army in Zama seems to demonstrate this: the Carthaginians used a triple line arrangement, sacrificing their first two lines of dubious quality and keeping their veterans from Italy in reserve for the final encounter. The placement of Hannibal was highly recommended given his weakness in cavalry and infantry, but he did not think about a system of relief between the lines as the Romans did. Each line fought its particular battle and the last one was finally destroyed against the Roman anvil when it received the attack of Numidian horsemen in the rear.

The legions lived and trained together for a longer time and were more uniform and efficient (unlike Hannibal's final force), allowing mediocre commanders to maneuver and position their forces more or less efficiently. These qualities, among others, made them more than a rival for the phalanx when they faced each other in combat.[17]​.

Pyrrhus' Falangist system was a trial by fire for the Romans. Despite several defeats, they inflicted such losses on the king of Epirus that the expression "Pyrrhic victory" became synonymous with useless victory. As a skilled and experienced commander, Pyrrhus arranged a typical mixed phalanx system, including war elephant shock troops, light infantry formations (peltasts), elite units, and cavalry to support the heavy infantry. Using this method he was able to defeat the Romans on two occasions, with a third battle of doubtful outcome or resulting in little Roman tactical victory. The battles below illustrate the difficulties of fighting against phalanx forces. If properly led and disposed (it is therefore interesting to compare Pyrrhus with the disposition of Perseus fleeing in Pydna), they presented a credible alternative to the heavy legion. The Romans, in any case, learned from their own mistakes. In the battles after the Pyrrhic Wars, they showed themselves to be perfect experts on the Hellenic phalanx.

• - Battle of Heraclea.

• - Battle of Asculum "Battle of Asculum (279 BC)").

• - Battle of Benevento "Battle of Benevento (275 BC)").

In this battle, the Macedonian phalanx occupied a preferred position on high ground. However, not all of their units had managed to position themselves due to the skirmishes prior to the battle. In any case, the advance of their right wing made the Romans lose ground, who counterattacked on the right flank and managed to progress against a somewhat disorganized Macedonian left wing. The outcome remained in doubt, until an unknown tribune detached 20 maniples from the Roman line and carried out an enveloping movement against the Macedonian rearguard. This caused the enemy phalanx to collapse, ensuring victory for the Romans. The more flexible and effective organization of the legionaries had taken advantage of the weaknesses of the dense phalanx. Such triumphs ensured Roman hegemony in Greece and neighboring territories.

At Pydna, the contenders deployed on a relatively flat plain, and the Macedonians had reinforced the infantry with a significant contingent of cavalry. When push came to shove, the phalanx advanced in a perfect line against the Roman line, making some initial progress. However, the ground on which it had to advance was somewhat rugged, and the powerful phalanx formation lost its iron cohesion. The Romans absorbed the initial shock and counterattacked; Their more spaced formation and incessant pressure proved decisive in hand-to-hand combat on uneven terrain. In close combat, the sword and shield neutralized the sarissa, and the supplementary weapons of the Macedonians (lighter armor and a shorter sword, the classic xifos) placed them at an inferiority against the skillful and aggressive assault by the Roman heavy infantry. Perseus failed to efficiently deploy support troops to help the phalanx in its time of need. In fact, it seems that he fled as soon as the situation began to deteriorate without even using the cavalry. The contest was decided in less than two hours, with a complete defeat for the Kingdom of Macedonia.

The techniques of breaking through enemy phalanxes further illustrate the flexibility of the Roman army. When facing Phalangist armies, the legions used to deploy the velites in front of the enemy with the order contendite vestra sponte, to cause confusion and panic in the solid blocks of the phalanx. Meanwhile, the sagittarii or auxiliary archers "Archer (army)") were placed on the wings, in front of the cavalry, to cover the retreat of the velites. These archers were usually ordered to eiaculare flammas - shoot incendiary arrows - as occurred at the Battle of Benevento "Battle of Benevento (275 BC)"). The cohorts then advanced in arrow formation, supported by the fire of velites and auxiliaries, and charged the phalanx at a specific point, breaking their formation. They then flanked it using cavalry to ensure victory.

Tactical superiority of Hannibal's forces. Despite not being a classic phalanx force, Hannibal's army was made up of "mixed" contingents and elements common to Hellenic formations. At the end of his life, Hannibal is said to have named Pyrrhus as the past commander he most admired.[25] Curiously, Rome had dented Pyrrhus's forces before Hannibal's birth, and given their advantages in organization, discipline, and resource mobilization, the question arises as to why they were not more effective against the Carthaginians, who for most of their campaign in Italy suffered from numerical inferiority and a shortage of supplies from their homeland.

Hannibal's individual genius, the professionalism of the bulk of his troops (forged after several years of constant fighting first in Hispania and later in Italy), and his superior cavalry seem to have been the decisive factors. In combat after combat, Hannibal took advantage of the Romans' tendencies, particularly their desire to achieve a decisive victory. The tired and half-frozen legionaries who emerged from the Trebia to form on the opposite bank of the river are a clear example of how Hannibal manipulated the Romans to fight under his conditions, and in the place of his choice. The subsequent debacles at Lake Trasimene and Cannae reduced the proud Romans to avoiding battle, stalking the Punics from the Apennines, unwilling to risk a direct confrontation on the plain, where the enemy cavalry had a clear advantage.

Roman tactical sophistication and ability to adapt. But, although Hannibal's feat underlined that the Romans were far from invincible, it also showed their long-term virtues. They isolated and eventually bottlenecked the Carthaginians, accelerating their withdrawal from Italy through constant maneuvering. More importantly, it was the counterattack they began in Hispania and North Africa. They were eager to repay the humiliation suffered in Italy and remained on the defensive, but with incessant tenacity they attacked elsewhere, to finally destroy their enemies.[17]

They also learned from those enemies. The operations of Scipio Africanus consisted of an evolution of those that Hannibal had previously faced, showing a higher level of innovation, preparation and organization (compared to Sempronius in the Battle of the Trebia, for example). Scipio's contribution consisted in part of implementing more flexible maneuverability of tactical units, instead of the triple-line frontal attack advocated by his contemporaries. He also made more efficient use of cavalry, a weapon traditionally despised by the Romans. Their operations included pincer movements, consolidated battle lines, and "reverse Cannae" formations along with cavalry movements. Their victories in Hispania and the African campaign demonstrated a new sophistication in the way of Roman warfare, and reaffirmed the Roman ability to adapt, persist and overcome difficulties.[26] See the battles in detail:.

• - Battle of Baecula.

• - Battle of Ilipa.

• - Battle of Zama.

Roman infantry against Celtic, Iberian and Germanic peoples

The view of Rome's Gallic enemies has changed a lot. Several ancient historians consider them retrograde savages, unscrupulous destroyers of the civilization and glory of Rome. Some more modern views see them as a proto-nationalist light, ancient freedom fighters who resisted the armored foot of empire. Their bravery as worthy adversaries of Rome is often celebrated, as is the sculpture of the dying Galatian. The Gallic opposition was made up of a large number of diverse people and towns, ranging geographically from the valleys of France to the forests of the Rhine, passing through the mountains of Helvetia; in such a way that it is difficult to categorize them in a homogeneous way. The term "Gaul" has been used interchangeably to name the Celtic tribes of Britain and Caledonia, adding more diversity to the people grouped under this name. From a military point of view, however, they seemed to share several general characteristics: tribal politics with a relatively sparse and unelaborated state structure, light weaponry, unsophisticated tactics, poor organization, high degree of mobility, and inability to maintain combat power in their field forces for a long period.[27]

Although popular annals show the power of the legions and a group of charismatic commanders rapidly massacring large hordes of "savage barbarians"[28]​ (like the opening scene of the 2000 American film "Gladiator"), Rome suffered many embarrassing defeats at the hands of these tribal armies. In the Republican period (around 390-387 BC), the Cisalpine Gauls under the command of Breno "Brenus (4th century BC)"), sacked the city of Rome. Even after the Punic Wars were over, the Romans suffered heavy defeats against the Gauls such as the disaster of Noreia or the Battle of Arausio, both during the First Cimbrian War. In the early imperial period, Germanic war bands inflicted on Rome one of its most severe defeats, at the Battle of the Teutoburg Forest, which ended in the annihilation of three imperial legions, and marked the limit of Roman expansion in central Europe. It was these partly Germanic tribes (most had some familiarity with Rome and its culture, and had Romanized themselves) who brought about the final ruin of Roman military power in the west. Ironically, at the end of the Empire, most of the fighting occurred between forces composed mainly of barbarians, on both sides.[29]​.

Whatever their particular culture, the Celtic and Germanic tribes proved to be tough opponents, achieving several victories against their enemies. Some historians show that massive combat sometimes occurred in compact Falangist-style formations, overlapping shields, and using shield cover during sieges. In pitched battle, they occasionally used an arrow formation when attacking. Their best hope for success lay in four main factors:.

Roman infantry against enemy cavalry

The cavalry of their enemies represented one of the toughest challenges that the Roman infantry had to face. The combination of ranged attack and shock force, with great mobility, that the cavalry represented, took advantage of the main weaknesses of the legion: its deployment and relatively slow movements.

Defeat at the hands of powerful cavalry forces is a recursive element in Roman history, as illustrated by the campaigns of Hannibal, where Numidian and Celtiberian horsemen repeatedly overran the flanks of the Roman formation, delivering devastating blows to the wings and rear. Hannibal's great victory at Cannae (considered one of the greatest military catastrophes of the Roman era) consisted mainly of infantry combat, but the main role was played by cavalry, as in so many other victories.

An even more dramatic demonstration of Roman vulnerability is shown in the numerous wars against the Parthians and their heavy cavalry. The Parthians and their successors used large numbers of lightly armored cavalry archers with fast horses to harass and skirmish with the enemy, and delivered the final blow with armored spearmen known as "cataphracts." Both types of troops used powerful composite bows that fired arrows powerful enough to pierce Roman armor. The cataphracts then served as shock troops, charging with the force of a battering ram against the Roman ranks, once they had "softened" after the swarms of arrows. At the same time, they used a "scorched earth" strategy against the Romans, refusing large pitched battles, while drawing them further and further into unfavorable terrain, where their supplies were scarce and they had no safe line of retreat. The devastating defeat of the Roman infantry at Carras made the Parthian cavalry seem invincible.

Alexander the Great had already used this method during his campaigns. He attacked the Asian horsemen with detachments of light infantry, skirmishers and archers, and drove them from the battlefield with charges of his heavy cavalry. The Roman variant used this same "combined arms" approach, giving greater importance to the role of infantry. In later times, however, the importance and numbers of cavalry grew: in particular, the eastern half of the Empire would rely almost entirely on its cavalry forces.

Even in the noon of the foot soldier, large units of light skirmishers were deployed with the legions, to intercept the fast horsemen at a reasonable distance. The Roman cavalry played an important role, consisting of "screening" the main force, intercepting entire detachments of marauding horsemen. Using these supports, the heavy legions were able to come into contact with enemy cavalry.

Modifications by Ventidius. The Roman general Publius Ventidius Basus took charge of the readjustment of the legion to face the mounted enemies, specifically the Parthians. Sent by Mark Antony to Syria to stop the Parthian invasion of 40 BC. C., he defeated the Asians up to three times, where he killed as many generals of Parthia.[44]​ The main tactical modifications contributed by Ventidio were:[44]​.

Assessment of the Roman infantry

Several of Rome's military campaigns display either sustained invincibility or dazzling genius. Roman performance in many battles was either unimpressive or disastrous. When it came to ambushes (such as the Teutoburg Forest debacle), the Roman forces seemed prone to receiving successive charges, as occurred centuries before at Lake Trasimeno. Throughout the republic, they were defeated by generals such as Pyrrhus, Hannibal and many other enemy leaders. They also suffered important defeats against mounted enemies, such as the Parthians or Sassanids. And yet, over time, the Romans not only recovered from these defeats, but for the most part finished off or neutralized their enemies. How was it possible that they achieved it in the face of such a variety of enemies, in different times and places, more numerous, better led or more prepared?

Some elements that made the Romans an effective military force, at a tactical and strategic level, were:

They were able to copy and adapt the weapons and methods of their enemies efficiently. Some weapons, such as the gladius hispanicus were adopted by the legionaries if they were more effective than their own weapons. In other cases, it was possible for the Romans to invite especially tough or dangerous enemies to serve in the Roman army, as auxiliaries. In the naval sphere, the Romans followed several of the methods used by the infantry, abandoning their old designs, copying and evolving the Punic trireme (using the corvus "Corvus (weapon)") among other structural details), converting naval battles into infantry combat on deck.[49]​.

Roman organization was more flexible than that of most of its rivals. Not only was it superior to that of the often massed and uncoordinated tribal peoples who comprised the bulk of its enemies; In contrast, Roman heavy infantry was capable of adopting different formations and combat methods depending on the situation. From the tortoise formation "Turtle (formation)") in sieges, to the infantry square used against mounted enemies, through combined units to confront the Iberian guerrilla. The triple line or board patterns also allowed changing from one formation to another in combat, and the hierarchical organization of the units allowed officers to do their jobs with high effectiveness. They were able to improvise ingenious tactics, as Scipio did at Zama, leaving wide gaps between the lines to allow the elephants to pass: placing velites on both sides to shoot them and push them back towards the Carthaginian lines, and then closing the gaps into a single line that faced the Italian veterans of Hannibal's army.

Discipline, organization and logistical systematization maintained combat effectiveness for long periods. It is worth highlighting the system of fortified camps or , which allowed the army a defense worthy of the best permanent fort, rest and resupply for battle. Roman logistics was capable of maintaining combat power over long periods, from routine resupply and storage of supplies, to the construction of military roads, state arsenals, and weapons factories. In the naval war, periodic convoys were organized, a key element in the defeat of Carthage. The death of a leader, as a general rule, did not appreciably demoralize the troops, as a new leader emerged and continued the fight. In the defeat inflicted by Hannibal along the River Trebia, 10,000 Romans escaped the disaster to safety, maintaining order and cohesion in retreat, as the line around them fled in disarray. This testifies to their tactical organization and discipline.[49]​.

Infantry decline: controversies

Every history of the Roman infantry confronts the factors that led to its decline. Such decline, of course, is associated with the decline of the economy, Roman society and political scene. Despite this, it is noteworthy that the final disappearance of Rome was the consequence of a military defeat, no matter how plausible the plethora of theories put forward by scholars and historians are, ranging from reduced tax bases, class struggle, or decline of its leaders.[50] Two of the main factors considered by military scholars will be discussed here: barbarization of the infantry and evolution to a "mobile defense" strategy. There are a number of controversies and conflicting opinions in this area.

To combat the increasingly frequent raids and attacks of their border enemies, the legions changed from a slow and heavy force to an increasingly lighter troop, in addition to introducing cavalry elements on an increasingly larger scale.

This meant that the new infantry lost the incredible attack power that the early legions had, which meant that, although the probability of entering battle was much greater, they had less chance of winning it. The smaller size of this new legion also influenced this fact.

The Roman horsemen, although fast, were very weak compared to the invading Huns, Goths, Vandals and Sassanids. This ineffectiveness was demonstrated at Cannae and later at Adrianople: in both cases, the cavalry was completely destroyed by a much superior mounted enemy better trained for this type of combat.

"Barbarization" is a recurring theme in many works on Rome (see Gibbon, Mommsen, Delbrück, and others). In essence, it is argued that the increasing barbarization of the heavy legions weakened the quality of weapons, training, morale and long-term military effectiveness. The weapons changes described above are just one example.[51]​.

It can be argued that the use of barbarian personnel was not a new fact. Although this is true, said use was clearly defined in the "Roman style": it was the barbarian personnel who had to adapt to Roman standards and organization, and not the other way around. In the decline of the Empire, however, this was not the case. Practices such as allowing the establishment of large contingents of barbarian population within the boundaries of the Empire, the laxity of the quality of Roman citizenship, increasing use of foreign troops and relaxation or elimination of the severe traditional discipline, its organization and control, contributed to the decline of heavy infantry.

The foederati emplacements, for example, consisted of large barbarian contingents settled in Roman territory, with their own organization and under their own leaders. Such groups showed a tendency to ignore the "Roman way" of organization, training, logistics, etc., in favor of their own ideas, practices and methods. These emplacements may have brought political peace in the short term for the Roman elites, but in the long term their effect was negative, breaking the traditional advantages of heavy infantry in terms of battle training, discipline and field deployment. Likewise, since the barbarians received equal or better treatment with much less effort, the "old guard" declined and received no incentives to perpetuate the old customs. Indeed, these contingents of "allies" often turned against the Romans, devastating and plundering wide areas and even attacking imperial army formations.

Twilight of the Elite Infantry

There are many other facets to the controversy over the end of the old legions, but whatever the school of thought, all agree that the traditional values ​​and weaponry of the old heavy legion fell into decline. Vegetius, a 19th-century writer, in what is one of the most influential military works in the Western world, highlighted this decline as part of an integrated team between cavalry and light infantry. In recent years, this formula that had brought so much success began to fade away. Caught between the growth of more lightly armed and disorganized infantry, and the increasingly numerous cavalry formations within the mobile forces, the "heavies" as a dominant force withered. This did not mean that they completely disappeared, but their massive recruitment, training, organization and deployment as an essential part of the Roman military system was greatly affected. Ironically, in the last battles of the Western Empire, the defeats suffered were inflicted by infantry forces (many fighting on the ground).

Historian Arther Ferrill notes that even towards the end, some of the old infantry formations were still in use. Such groups were becoming less and less effective, lacking the severity in order and discipline, instruction and organization of the old days. At the Battle of Chalons (c. 451), Attila the Hun harangued his troops, mocking the once-respected Roman infantry, claiming that they did nothing more than huddle behind a screen of shields in close formation. He ordered his troops to ignore them and attack the powerful Alans and Visigoths instead. It was a sad commentary on the force that had once dominated Europe, the Mediterranean and most of the Middle East. Although it is true that at Chalons the Roman infantry contributed to the victory by capturing high ground in the middle of the battlefield, their days had already passed, it was time for the massive levies of foederati barbarians.[54]​.

Grades

• - Portal:Ancient Rome. Content related to Ancient Rome.

• - Wikimedia Commons hosts a multimedia category on Roman Infantry Tactics.

• - Wikisource contains original works by or about Roman Infantry Tactics.

• - The exercitus hispanicus from Augustus to Vespasian; text in PDF.

• - Flavius ​​Arriano: Tactics.

• French text, with comments in the same language, on the site of Philippe Remacle (1944 - 2011).

• - Flavio Arriano: Mobilization plan against the Alans.

• - Greek text, with electronic index, in the Perseus Project. Using the active tag "load" at the top right, you get help in English with the Greek vocabulary in the text.