Warfare of the Roman Republic

Dates 753-27 b.c.e.

Military Achievement

According to tradition, the city of Rome was founded on the banks of the Tiber River in 753 b.c.e. by Romulus, one of the twin sons of Mars, the Roman god of war. At the time of its founding, Rome’s proud future still lay far in the distance. A dynasty of foreign kings from neighboring Etruria eventually settled at Rome and dominated the institutions of the city. Although this early history is uncertain, Rome’s levy seems to have relied on the wealthy, because they could afford their own equipment for battle. Armed like Greek hoplites, Roman soldiers fought with thrusting spears, and, using a Greek formation—the phalanx—they stood shoulder to shoulder, with shields locked together.

After expelling the last of the Etruscan monarchs in 510 b.c.e., the Romans installed a Republican government, dominated by the Senate, and kept the Greek style of fighting. About a century later, however, some changes were introduced during a long war with Veii, an Etruscan stronghold north of Rome. In need of more soldiers, the Romans began recruiting more broadly. These new recruits, unable to afford full protective armor, adopted the scutum, a long Italic shield, in place of the hoplite’s round buckler. Moreover, the Romans introduced pay for military service and, for the first time, provided at public expense a horse for every new member of the cavalry.

The Roman victory over Veii was followed by defeat on the Allia, a stream about 11 miles north of Rome. There, in around 390 b.c.e., Gallic warriors overwhelmed the Republic’s forces, capturing and plundering the city before moving on. The conquering Gallic chieftain Brennus uttered the harsh words “Vae victis,” meaning “Woe to the vanquished!” This disaster revealed Rome’s military weaknesses and stirred reform. No longer fighting as a single compact body, the Romans came to employ a looser formation, composed of small units, or maniples. After abandoning the thrusting spear, Rome’s soldiers also came to adopt a throwing spear.

Eventually Rome’s influence managed to spread beyond the neighboring communities of Latium and into southern Italy. Greek cities, established there centuries earlier, called on Pyrrhus of Epirus (r. 297-272 b.c.e.) to stop the advance. With his war elephants, Pyrrhus defeated Rome’s forces at Heraclea (280 b.c.e.) and Ausculum (279 b.c.e.) but also suffered enormous casualties. He exclaimed that another victory such as his last would be the ruin of his army. After Beneventum in 275 b.c.e. he withdrew from Italy, never to return. By 264 b.c.e. Rome controlled all of the Italian peninsula except the Po valley in the north.

Rome then turned to Sicily, vying for control of the island with Carthage, a powerful city on the North African coast. During the First Punic War (264-241 b.c.e.), Rome mobilized large fleets for the first time. Although Romans were inexperienced at sea, Rome’s invention of a grappling hook and boarding bridge allowed soldiers to cross over to enemy ships and fight on their decks like infantry. With a final naval victory in 241 b.c.e., Rome expelled the Carthaginians from Sicily.

A generation later, the Second Punic War (218-201 b.c.e.) revived old grudges. With an eternal hatred of Rome, the Carthaginian general Hannibal (247-182 b.c.e.) planned to win the war through a bold surprise invasion of the Italian peninsula. Hannibal made a winter crossing of the Alps to enter Italy and gain victories at Trebbia (218-217 b.c.e.), Trasimeno Lake (217 b.c.e.), and Cannae (216 b.c.e.). However, Rome sent forces against his base in Spain and eventually confined him to the “toe,” or southernmost tip, of Italy. After sixteen years in enemy territory, Hannibal finally withdrew to Africa, where he was crushed at Zama (202 b.c.e.) by Scipio Africanus (236-184 or 183 b.c.e.). Hannibal escaped the battlefield and urged his countrymen to surrender. Carthage lost some of its African territory to Rome’s allies, and Spain was eventually organized as Roman territory.

Hannibal’s alliance with Philip V (238-179 b.c.e.) of Macedonia led to two Macedonian Wars, in which Roman troops crossed the Adriatic Sea and at last secured victory at Cynoscephalae in 197 b.c.e. Although Macedonia survived and Greece was declared free, Rome’s influence came to dominate the whole area. Once involved in the eastern Mediterranean, Rome’s forces also accepted the challenge of Syria’s Antiochus III (242-187 b.c.e.), also known as Antiochus the Great. After victory at Magnesia in 190 b.c.e., the Republic refused to annex any new territory, but it now arranged the affairs of Hellenistic Asia as it wished.

At Pydna (168 b.c.e.) the Republic defeated Philip’s son, Perseus (c. 212-c. 165 b.c.e.). Macedonia was eventually organized as a Roman province, and its governor was made responsible for Greece. Moreover, Egypt was treated like a dependency. When Antiochus IV (c. 215-164 b.c.e.) invaded the Nile Delta, a Roman ambassador is said to have drawn a circle around the Syrian king and commanded him to order a retreat before stepping out of it. The Third Punic War (149-146 b.c.e.) resulted in the complete destruction of Carthage in 146 b.c.e., and the city’s remaining territory became the province of Africa. Thus with the defeat of Carthage and Hannibal’s allies, the Republic had destroyed its greatest enemies. Although more wars lay in the future, Rome’s long-term dominion was ensured.

Weapons, Uniforms, and Armor

The ancient sources present a reasonably clear picture of the Republic’s military affairs as it emerged from the struggle with Hannibal. All Roman citizens between the ages of seventeen and thirty-six were liable for service. The maximum length of service was likely sixteen years for infantry and ten for cavalry, but in normal circumstances a soldier would probably serve for up to six years and then be released.

The number of the main infantry division, the legion, is given as 4,200 soldiers, but in emergencies it could be higher. The legion was drawn up in three lines of hastati, principes, and triarii, with the youngest and poorest forming the velites. As lightly armed skirmishers, the velites carried a sword, javelin, and small circular shield. The hastati and principes, in contrast, were heavily armed. Protected by the long Italic shield, they relied upon a short Spanish sword, or gladius, and two throwing spears, or pila. Like the hastati and principes, the triarii were also heavily armed, but they carried a thrusting spear, or hasta, instead of the pilum. All soldiers wore a bronze breastplate, a bronze helmet, and a pair of greaves, or shin guards. In order to be distinguished from a distance, the velites covered their helmets with wolfskin, and the hastati wore three tall feathers in their helmets. To preserve a degree of exclusiveness, wealthy recruits wore shirts of ring mail, whether serving among the hastati, principes, or triarii.

Military Organization

The supreme magistrates of the state, the two consuls, usually served also as generals of the army. Elected to serve for one year, each consul traditionally commanded two legions. His authority, called imperium, was absolute beyond the walls of the city. The fasces, a bundle of rods and axes bound together by red thongs, symbolized the consul’s power of life and death. After victory, the consul was decked with laurel and borne before the general by twelve attendants, or lictors, proceeding in single file.

The general’s senior officers included the military tribunes. With six in each legion, all tribunes were required to have significant military experience and to meet stringent property qualifications. Usually most, if not all, were elected. They had some important military responsibilities. As elective officers, they more often tended to the welfare of the soldiers. By the early second century, it was also customary for the general to be accompanied by legates. Appointed by the Senate on the general’s advice, these were often ambitious young men from prominent families, who had little military experience.

The real strength of Rome’s military was the centurions, career officers who, as one contemporary observed, held their ground when bested and stood ready to die at their posts. There were sixty centurions in each legion, with two in each of thirty maniples. Selected by the tribunes, the centurions were organized into a hierarchy with a well-defined order of promotion. Every centurion’s ambition was to serve as primus pilus, senior officer of the first maniple, because the holder of that title was recognized as the best soldier of the legion and given a seat on the general’s war council.

In addition to infantry, the legion had three hundred cavalrymen. They wore linen corselets and relied on strong circular shields and long spears. They were divided into ten units, or turmae. Each of these had three decurions, and the most senior of the three always exercised command. Allied contingents, recruited from throughout Italy, also campaigned with Rome’s citizen army. In fact, there was at least one legion of allies, if not more, for every legion of citizens. Known as socii, they were organized and equipped like Romans. They were also commanded by Roman citizens called praefecti. An elite corps, the extraordinarii, was selected from the best of the allies, horse and foot. The rest were divided into alae, right and left wings, reflecting their positions on the army’s flanks. The great numbers of the socii especially contributed to the might and effectiveness of Rome’s forces.

Doctrine, Strategy, and Tactics

After assembling with their arms, the soldiers would be ordered to pitch camp. It resembled a city, complete with a forum and tents arranged in neat rows. The via principalis, or “first street,” ran past the tents of the senior officers, and the via quintana, or “fifth street,” paralleled the main boulevard. During the time of the Republic, these camps were usually temporary. Because commanders always employed the same plan, every soldier knew the camp’s layout and could find his way around, even in the dark. In addition to soldiers and officers, the camp also housed animals, equipment, baggage, and sometimes plunder taken from the defeated enemy. Moreover, there were hosts of camp followers. In 134 b.c.e. , for example, numerous traders, soothsayers, and diviners, as well as two thousand prostitutes, were cast out of a camp near Numantia in Spain.

Yet the camp remained an integral part of Republican strategy. As an entrenched fortress, it provided a base for attack and a safe retreat in the event of defeat. The guarding of its gates therefore required discipline. Those who fell asleep during the night watch were usually stoned to death. This harsh discipline extended to the field of battle, where a maniple, giving ground without good reason, could be, literally, “decimated.” A tenth part of its men, selected by lot, would be clubbed to death, while the rest would be ordered to sleep outside the camp’s fortifications on an unprotected spot. In contrast, there was also a system of military decorations to reward exceptional bravery. The general praised heroic soldiers before the assembled army and gave them prizes. To the first man mounting the enemy’s walls, for example, he conferred a crown of gold.

On breaking camp, procedure had to be followed. On the first signal, the soldiers took down their tents. On the second, they loaded the pack animals. On the third, their march began. When attack was not expected, all moved in one long train, the extraordinarii leading the way. In times of danger, a different marching order prevailed. The hastati, principes, and triarii formed three parallel columns. When the enemy appeared, the maniples turned to the left or to the right, clearing the baggage trains and confronting the enemy from whichever side necessary. Thus in a single movement, the army placed itself in good battle order.

When engaging the enemy, the legion approached in three lines: first, the hastati; second, the principes; third, the triarii. Each line consisted of ten maniples, drawn up with gaps between them, equal in width to the maniples. These gaps usually alternated in each row, like dark spaces on a checkerboard. Thus the gaps in the first line adjoined the maniples in the second line. Likewise, gaps in the second line adjoined maniples in the third.

Traditionally, the battle followed a more or less schematic plan. Forming a light screen, the velites opened with a hail of javelins and retired to the rear through the gaps. Then the hastati, closing the gaps in the first line, offered a united front against the enemy. After surging forward in unison and striking with their swords, the soldiers soon recoiled, rested, and tried again. If the assault continued to fail after many attempts, the hastati retired through the gaps in the line of the principes, who next advanced and attacked in the same manner. If the principes also failed, then they retired through the gaps in the line of the triarii, who proceeded to the final trial of strength, reinforced by survivors from the first and second lines. The Romans thus refused to expose all their forces to a frontal assault, keeping part of them in reserve, while the rest engaged the enemy.

On the whole, Roman strategy aimed at the destruction of the enemy in pitched battle. This strategy sometimes employed flexible tactics. In 169 b.c.e., for example, the Romans borrowed a formation from the gladiatorial arena. In this formation, called the “tortoise,” or testudo, several ranks locked their shields together and formed a sloping roof over their heads. They advanced to the lowest part of the enemy’s wall, where some of the Romans then mounted the roof of shields. After moving up its slope, they occupied the high end, where they fought face to face with the wall’s defenders. Finally overwhelming their opponents, the victorious Romans crossed over into the enemy city and captured it.

Under a strong general, the storming and plundering of a city proceeded by well-defined stages, announced by signals. First the troops slaughtered. Next theylooted. Finally they disposed of theirspoils, with the profits distributed equally among all the soldiers. More often, however, the general made little attempt to restrain them. They held the power of life and death, and they did whatever they wished to the inhabitants of a captured city. In these cases, of course, every soldier looted for himself, and everything he laid his hands on became his private property.

Saluted as imperator by his troops, the successful general looked forward to a triumph, the most distinguished reward conferred by the Senate for military achievement. This ceremony celebrated important victories and was granted only under certain conditions, such as extraordinarily numerous enemy casualties and significant expansion of Roman territory. The triumph was a magnificent procession in which the victorious general, with laurel wreath on his brow and ivory scepter in his hand, mounted a chariot drawn by white horses and paraded through the streets of Rome. Before him were the spoils of conquered cities and captive leaders imprisoned in chains. After him followed his troops in military array, enjoying unusual license and singing bawdy songs. The procession formed upon the Campus Martius, the field of the war god Mars, and entered the city through the Triumphal Gate. It then ascended the Capitol, where the general offered sacrifice and dined with Jupiter, the king of the gods and goddesses. The entire population participated with unbounded jubilation in this ceremony of great pomp and circumstance. After all, the general was, at least temporarily, a god-king. However, as a reminder, a slave would be stationed near the general throughout the parade, occasionally whispering in his ear, “Remember! Thou art a man.”

Reforms of the Late Republic

Although late second century b.c.e. Roman legions again met defeat, eventually Gaius Marius claimed victory for the Republic, in Africa over King Jugurtha (c. 160-104 b.c.e.) of Numidia and in northern Italy over the Teutons (102 b.c.e.) and the Cimbri (101 b.c.e.). While holding an unprecedented series of consulships in 107 and from 104 to 100, Marius encouraged military reform, and he has been credited by some with the conversion of Rome’s citizen militia into a standing professional force. Marius undoubtedly played an important role in the evolution of Rome’s military.

As in past crises of state, Marius opened the ranks to the capite censi, citizens who failed to meet prescribed property qualifications for military service. He likely viewed this measure as a temporary emergency action, but later generations followed his example. Immersed in wars both foreign and domestic, Marius’s successors abandoned all restrictions on liability for service and recruited more troops than ever before. Because most of these soldiers came from poor families, the State equipped them at public expense. So variations in arms and armor soon disappeared.

Marius also made fundamental changes in tactical organization, preferring the cohort to the maniple as the basic unit within the legion. Marius’s new cohort consisted of three maniples, one drawn from each line: hastati, principes, and triarii. As a result, his cohort was a microcosm of the old legion. The First Cohort consisted of the three maniples situated on the extreme right of the old lines. The last cohort, the Tenth, moving from right to left, consisted of the three maniples on the extreme left.

Marius’s new legion drew up for battle in three lines. There were four cohorts in the first line, three in the second line, and three in the third. The cohorts likely had a standard size, which under the Empire was 480 men. Thus the new legion seems to have had a strength of 4,800 men, organized into ten cohorts and thirty maniples. The velites were apparently abolished. Eventually the Roman army incorporated contingents raised outside Italy. These new contingents carried their national weapons and were called auxilia. Some came from independent allies, others came from forced levies, and still others were paid as mercenaries.

In the press of battle, standards, banners on long poles, served as a rallying point. Marius gave preeminence to the aquila, or eagle, as the legion’s chief standard. The legion had previously used a variety of standards, including the eagle, wolf, minotaur, horse, and boar, among others. Yet by the Republic’s close, the eagle shared importance only with the standards of the hastati and principes, which consisted of slender poles decorated with circular bosses. The primus pilus, the best soldier in the legion, acted as aquilifer, or eaglebearer. To lose or surrender the aquila was, of course, a great disgrace for the entire legion.

Along with these changes, Marius modified the pilum. The iron tip of Rome’s heavy spear was joined to its wooden shaft by two iron rivets. Marius replaced one of these with a wooden pin, and on striking a target the shaft now snapped off. The spear could no longer be picked up and thrown back at its owner. Moreover, Marius wished to reduce the great numbers of pack animals, because they slowed the army’s march, so he required his troops to carry equipment and rations on forked poles flung over their shoulders. As the general’s beasts of burden, the legionaries came to be called “Marius’s Mules.”

Wars of the Late Republic

In Marius’s later years, violence spread across the Italian peninsula, with serious repercussions for the Republic. Weary of Rome’s stern ascendancy, the Italian allies rose in revolt. Fearful but wise, Rome promised citizenship to all who laid down their arms. Although the Social War (91-88 b.c.e.), as it was called, soon ended, the riot of its daily warfare created an angry generation whose sons found lodging in Rome’s legions, filling them with a spirit of apathy and callousness. These soldiers cared little for the Republic and were loyal only to the general who paid them.

Almost inevitably, civil war followed the Social War. As one of its leaders, Marius died in 86, before destroying all of his opponents. His archenemy, Lucius Cornelius Sulla (138-78 b.c.e.), survived to conduct a great bloodbath and hold untrammeled authority until his own death. Under these chaotic conditions, only small military gains were made abroad. Yet when Mithridates VI of Pontus seized Asia Minor and invaded Greece, he was defeated by Pompey the Great (106-48 b.c.e.), who annexed Syria and Palestine, thereby enlarging Rome’s Asiatic dominion.

Only a few years later, bold adventures began to unfold in Gaul. Julius Caesar (100-44 b.c.e.) embarked on a war of conquest against warrior Celts and their powerful priests, the Druids. With his small force, Caesar opposed the large Celtic armies and eventually defeated the Gallic tribes, organizing their territories as a province. At the same time Caesar accelerated the gradual professionalization of the Roman army.

Caesar followed tradition by relying upon the cohort and the centurion, although his military tribunes were mostly young men with political charges. Yet Caesar’s legates, ten in number, played an essential role in his command structure. Acting as subordinate commanders, some commanded legions and auxiliary forces, while others managed the camp and secured the surrounding region. Perhaps even more important, Caesar’s battle order responded dramatically to topography. He exploited flank attacks, for example, and often held troops in reserve for the decisive onslaught. Caesar thus helped to liberate Roman warfare from the traditional scheme of advance and assault.

Like a great Hellenistic king, Caesar raised siege towers, built bridges to span fierce rivers, and dug elaborate entrenchments around enemy bases. His formidable artillery included giant catapults, which fired heavy stones, and smaller scorpions, which fired arrows with extraordinary accuracy. Apart from his tactical expertise, Caesar’s personal qualities also invited his success as a commander. More often than not, his decisiveness and instinct compensated for his reckless daring.

Despite the continued Roman military success, by 49 b.c.e. the Republic was again divided by civil war. Caesar crossed the Rubicon and swept through Italy into Greece, where he defeated Pompey. Embroiled in Rome’s affairs, the Pharaoh of Egypt soon fell to Caesar’s arms as well. Then Pharnaces (r. 63-47 b.c.e.), son of Mithradates the Great, took his turn, losing at Zela (47 b.c.e.). To underscore the rapidity of this victory, Caesar employed three short words, “Veni, vidi, vici,” meaning, “I came, I saw, I conquered.” Other civil war battles followed in Africa and Spain. Caesar prevailed in all and returned to Rome with unprecedented power, as dictator for life. However, by the Ides of March, 44 b.c.e. , he lay dead, murdered by conspirators.

Through civil war Caesar’s heir, Octavius (63-14 b.c.e.), claimed unrivaled supremacy. He then adopted a new name, Caesar Augustus, and, ruling as Rome’s first emperor, he replaced the citizen militia of the Republic, which had become increasingly unmanageable and restless, with a smaller professional force. Legionaries eventually served for twenty-five years, enjoyed promotion through the ranks, and received generous cash payments on discharge. Except for a special corps, they were stationed in the frontier provinces, at a safe distance from the imperial capitol. Augustus’s reign thus signaled a new epoch in Roman political and military history, as well as the end of the Republic in 27 b.c.e.

In conclusion, the military institutions of the Republic proved extremely durable and successful. With great adaptability, the Romans learned from their opponents, borrowing weaponry and improving tactical structure. Rome’s forces were also guided in a few critical moments by generals of genius. Yet the most fundamental reason for the Republic’s success lay in its manpower, fueled by the populations of Italy, which allowed the Romans to ignore defeats. Thus Rome’s military evolved from obscurity into a remarkable institution, which eventually dominated the ancient Mediterranean and shaped one of history’s longest-lived empires.

Ancient Sources

Most historians contemporary with the Republic discussed military affairs, yet few of these scholars were actually eyewitnesses to councils of war and victories on the battlefield. However, there are two notable exceptions. First, the Greek author Polybius (c. 200-c. 118 b.c.e.) saw the Roman army in action against fellow Greeks, and later he seems to have accompanied a Roman general on military campaign. In his Histories (first appearing in English as The General History of Polybius: In Five Books, 1773), Polybius gives an important description of the Roman army as it emerged from the struggle against Hannibal. Second, Julius Caesar provides a valuable narrative of the Roman army at war. He recounts his own activities as general in Gaul, Germany, and Britain throughout a period of almost ten years. Caesar’s Comentarii de Bello Gallico (51-52 b.c.e. ; Commentaries, 1609) explores a wide range of the Republic’s military institutions and activities as they existed in the first century b.c.e.

Turning Points

753

• The city of Rome is said to be founded on the banks of the Tiber River by Romulus, one of the twin sons of Mars, the Roman god of war.

c. 390

• Gallic warriors overwhelm the Republic’s forces, capturing and plundering the city of Rome.

241

• In the final naval victory of the First Punic War, Rome expels the Carthaginians from Sicily.

202

• Rome defeats Carthage at the Battle of Zama.

168

• The Roman Republic defeats Macedonian king Philip V’s son, Perseus, at Pydna, eventually organizing Macedonia as a Roman province.

146

• Rome defeats Carthage in the Third Punic War, destroying its greatest enemy and ensuring its long-term dominion.

60

• The First Triumvirate is formed.

27

• Augustus establishes the Roman Empire.

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