The rise of Rome and the spread of its empire were due largely to the growth and development of the Roman army and a mastery of the art of war. The Romans treated warfare as a science, constantly developing new tactics and learning from their enemies. Whereas the Greeks relied on the same basic formations and tactics for hundreds of years, the Romans were constantly seeking ways to improve their military performance. This spirit of adaptation and innovation enabled the Romans to remain a dominant military force for centuries.


Rome was primarily a land power, and its military strength was based on its army. The early Roman army, like the armies of ancient Greece, consisted of citizen-soldiers who served only in times of war and crisis. From the Greeks, the Romans adopted a basic military formation known as the phalanx, a group of warriors arranged in a tight formation of columns and rows. The phalanx was well suited to an army whose soldiers had little training in weapons skills. Because it required soldiers to fight as a single unit, the phalanx relied primarily on discipline, order, and strength of numbers, rather than on military ability.

A well-coordinated phalanx was difficult to destroy and could be a formidable attacking force. But it lacked the ability to move quickly and to respond swiftly to changing conditions in battle. The Romans recognized this shortcoming and abandoned the phalanx in the early 300s B.C. In its place they introduced the legion, a military unit that remained the basis for the organization of the Roman army for centuries.

Roman Legions. A Roman legion consisted of between 4,200 and 6,000 men, organized into units called maniples of 60 or 120 men. The soldiers in each maniple were armed with heavy spears and protected by large rectangular shields, bronze helmets, and breastplates. A legion also contained lightly armed infantry, or foot soldiers, and cavalry—soldiers on horseback. The great advantage of the maniple over the phalanx was its flexibility and maneuverability. A phalanx was effective only if the men remained tightly packed together. Maniples, however, could be detached easily from a legion and used to attack a weak point in an enemy formation or dispatched to another part of the battlefield.

The organization of the Roman legion remained unchanged for nearly 200 years. However, partly as a result of encounters with the brilliant Carthaginian general Hannibal during the Punic Wars, the Romans created a new military formation, the cohort, and made it the basic unit of the legion. A legion contained ten cohorts, each with between 300 and 600 men. The cohort increased the flexibility of the legion. Because the cohort was a larger formation than the maniple, individual cohorts could be used more effectively against an enemy. Moreover, unlike the maniple, in which soldiers carried different weapons, every soldier in a cohort had identical weaponry and armor. Thus all cohorts could, in theory, perform equally well in battle.

Battle Tactics. The Roman army developed standardized battle tactics. Cohorts generally were lined up in battle formation and commanded to remain still and quiet until the enemy came within range of their javelins*. The legionnaires would then hurl these weapons, hoping to disrupt the enemy’s advance and spread confusion in their ranks. The legionnaires next drew their short swords and plunged forward in a wedge formation, forcing enemy troops together in order to limit their ability to use long swords or spears. Meanwhile, the cavalry circled the enemy in search of weaknesses in their battle formation. If weak points were found, a cohort might be sent to attack that spot. If the enemy tried to flee or regroup, the cavalry would charge from the rear, forcing the enemy back into the Roman infantry. These tactics had devastating results against most opponents.

* javelin long wooden spear with a pointed tip, designed to be thrown


One reason for the success of the Roman army was the toughness of its soldiers. Military training was rigorous, and legions were often forced to march great distances and then fight at a moment's notice. During the Punic Wars, one Roman army marched 200 miles in six days and engaged in battle as soon as it reached its destination. A Roman soldier who failed in his duty could expea severe punishment, including being beaten by his fellow legionnaires. If a whole unit had shirked its duty, every tenth man in the unit was beaten. The rest of the men received reduced rations and were forced to pitch their tents outside of the amp, leaving them vulnerable to attack.


The Romans had a great ability to adjust to new situations. Whenever they faced a new situation, enemy, tactic, or weapon, they learned from the experience and adopted ideas or technology that seemed superior to their own. They also made changes in the things they adopted, improving them and making them more suitable to their own needs.

A Professional Army and the Loyalty of Troops. The early Roman army consisted of citizen-soldiers who served for short periods of time and then returned to their farms and businesses. As the Romans began fighting battles far from Italy, it was no longer possible for soldiers to return home at the end of a military campaign. Instead, they often remained on duty overseas for long periods of time. This resulted in the rise of a professional army, which provided opportunities for long military careers.

With a core of long-serving professional soldiers among his troops, a general of exceptional ability could secure their loyalty and demand extraordinary service from them. Military training included long and rapid marches and conditioning to enable soldiers to make sudden changes in tactics during combat. Such training allowed Roman troops to surprise an enemy and exploit weaknesses that arose in the course of battle.

Using elements of surprise and tactical flexibility, the general Scipio Africanus won great victories over Carthage during the Punic Wars. The skill and tactics of the brilliant general Gaius Marius enabled the Romans to defend Italy from the Germans who invaded in the 100s B.C. These and other outstanding generals changed the training and tactics of the Roman army, thereby increasing its flexibility and improving its ability to recover quickly from misfortune or setbacks.

The loyalty of the troops to their general played an important role in the civil wars that occurred during the late Roman Republic*—as troops with allegiances to different leaders fought against each other. During the Roman Empire, legions influenced the succession of emperors, and several emperors were deposed by the military.

Responding to New Opponents and Situations. During the imperial* period, the nature of Roman warfare changed in several ways. The composition and role of the Roman legions were altered and a naval fleet was established.

The Romans made several changes in response to the presence of mounted enemies to the north (the Germans) and to the east (the Parthi- ans). Rome developed stronger infantry formations and created special units of javelin throwers and archers, which were incorporated into legions alongside the cohorts. The Romans also placed an emphasis on all types of cavalry. Specialized fighting units, such as Syrian archers and Spanish cavalry, were drawn from conquered territories and transferred throughout the empire as needed. These auxilia, or auxiliaries, became an integral part of the Roman armies.

* Roman Republic Rome during the period from 509 B.C. to 31 B.C., when popular assemblies annually elected their governmental officials

* imperial pertaining to an emperor or empire

During the reign of the emperor Augustus, Rome began developing naval fleets to patrol the Mediterranean and Black seas, as well as the Rhine and Danube rivers. These fleets were second to the Roman army, however, largely because the Romans controlled the Mediterranean and faced little threat at sea. The primary responsibility of the fleets was to protect trading ships and coastal settlements from pirates.

As they extended their empire, the Romans made changes in military strategy to accommodate their new responsibilities. The emperor Vespasian, for example, improved living conditions for troops in the field and standardized the layout of frontier fortifications. The emperor Hadrian initiated a policy of marking the boundaries of the empire with new and stronger defense lines. The most imposing of these is Hadrian’s Wall, a stone barrier in northern Britain, many parts of which still exist—almost intact.

Adopting a Defensive Strategy. The reign of Hadrian marked a watershed in the history of Roman warfare. Up to that time, the Roman army served as an attacking force. It had always tried to engage the enemy in open battle where its superior equipment, tactics, training, and discipline would ensure overwhelming victory. By the late A.D. 100s the Romans had begun to turn away from a policy of territorial expansion and military aggression. Instead they adopted a more defensive strategy. The focus of Roman military power was now to defend the imperial frontiers from attack by barbarians and to maintain peace within the provinces*.

This new defensive strategy led to more changes. Instead of maintaining several legions in the field, the Roman army came to rely on smaller military units, many of which were stationed permanently in frontier outposts and fortified towns. The outposts became more heavily fortified, and they were equipped with large-sized artillery* mounted on towers and walls. Mobile armies were formed by taking some soldiers from the legions in the provinces, leaving the majority of each provincial force in place and ready for defense. The division of troops between mobile and stationary armies usually meant that most stationary troops were the older soldiers, while the mobile armies consisted primarily of younger and more skilled men.

By the A.D. 400s the strength of the Roman army—its ability to adapt, the skill of its leaders, and its rigorous training and discipline—had been severely eroded. In the western part of the empire, its effectiveness as a fighting force was greatly reduced. The eastern part of the empire, however, maintained its military strength by recruiting skilled forces from its provinces and placing them under the command of qualified leaders. Perhaps more important, the eastern empire did not face a serious threat until hundreds of years after the barbarians overran the west and conquered Rome. Nevertheless, Rome left a legacy of military power and organization that was unrivaled for well over a thousand years. (See also Armies, Greek; Armies, Roman; Class Structure, Roman; Naval Power, Roman; Wars and Warfare, Greek.)

* province overseas area controlled by Rome

* artillery heavy weapons used for hurling large missiles, such as stones, at the enemy

If you find an error or have any questions, please email us at admin@erenow.net. Thank you!