It was Rome's military that allowed it to rise above all others and dominate the Mediterranean basin for more than a millennium. Rome's military adapted and evolved over the centuries in order to overcome the new threats it faced as its territories expanded further and further.

GIF of Roman Territories Roman Territories GIF

Page Contents

Recruitment, Oaths and Training

The recruitment and training of soldiers is one of the largest tasks faced by any military, whether it be in the first century or the twenty-first. This was a task not taken lightly by the Roman Senate or its generals. Tight restrictions were placed on who could join the Roman army in order to maximise its effectiveness.

The training of new recruits was a harsh and uncompromising task aimed at giving Rome's soldiers a decisive edge over the enemy. I guess they didn't do too badly considering all that land they conquered...


Rome's approach towards recruitment changed significantly over the many centuries it prospered for. During the Roman Kingdom and most of the Roman Republic (753 BCE to 107 BCE), all eligible men were forcibly conscripted to perform military service.

In Rome, citizens were placed into one of five classes based on their wealth. To serve in the Roman army, a man had to belong to one of these five classes, which meant they had to have a minimum wealth of 11,000 asses.

Why was this a requirement? Well, a soldier had to provide their own weapons and armour. This meant that those in the lower classes would serve as skirmishing or light infantry units; whereas those in the upper classes would belong to the heavy infantry or cavalry.

Class Min. Wealth (Asses) Equipment
I 100,000 Helmet, breastplate, greaves, round shield, spear and sword
II 75,000 Helmet, greaves, oblong shield, spear and sword
III 50,000 Helmet, oblong shield, spear and sword
IV 25,000 Oblong shield, spear, javelin, and sword
V 11,000 Sling, stones, javelin

(The minimum wealth requirement to join the military was reduced to 4,000 asses during the Punic Wars and then further reduced to 1,500 asses in 140 BCE.) (A soldier would be excluded from further military service if he had served sixteen campaigns as an infantryman or ten campaigns as a cavalryman.)

In order to raise an army, the Roman Senate would issue an edict allowing magistrates to summon all eligible men for service. All eligible men would have to go to the Capitoline Hill thirty days after the edict had been issued. Here a soldier would either be conscripted or make his case for being excluded from military service.

Marian Reforms

The greatest change to recruitment came following Marius' reforms in 107 BCE, which turned the Roman military from a part-time force into a full-time professional army. Under these reforms:

  • Men no longer had to own land or have a minimum wealth to enlist in the army
  • All soldiers were provided with weapons and armour by the state
  • Army was organised into legions of roughly 4,800 soldiers
  • Soldiers served for a total of sixteen years (Later increased to twenty-five years)
  • Training and equipment were standardised
  • Citizenship offered to all Italian allies who enlisted in Roman legions
  • Soldiers received land for farming after retirement
  • Soldiers received a portion of the booty won on campaigns

These reforms drastically increased the number of people eligible to serve in the army. As a result, many of Rome's poorest citizens flocked to enlist in the army. These changes also meant that Rome had a standing military force which could respond to threats immediately rather than having to raise, train and deploy a force.

After the Marian Reforms, citizens would report to recruitment posts fro generals who were looking for soldiers. The ideal recruit would be:

  • At least 1.75 meters tall (5.8 feet)
  • Late teens / early twenties
  • From a manual labour background (blacksmiths, butcher, etc.)

After a man had made reached a recruitment post they would undergo probatio. This is where the recruit's physical capabilities were assessed before he received his position. (If they had skills, for example, as an accountant, they would be given a bookkeeping role.) After probatio had been completed the new recruits would begin four months of training to prepare for life in the Roman army.

Roman soldiers might also be transferred from one legion to another. This began to happen more during the later years of the Roman Empire, known as 'vexillaio', small groups of soldiers would be re-deployed from one region to another. Once they had completed their objective, they would return to their original post.


After recruitment, each soldier would have to take an oath, known as the 'sacramentum militare'. By taking the oath a soldier denounced his civilian rights, and if he broke it, he would be at the hands of his commander and whatever punishment he saw fit. By taking the oath, he swore to follow all orders he was given, including that:

  • He would stay at his post unless given leave by an officer
  • He would not steal from the army
  • He would not abandon his weapons
  • He would not flee from battle
  • He would die for Rome

The daily life of a soldier was pretty intense with long marches carrying heavy equipment; this was enough to keep them in good physical condition. Roman soldiers would also participate in several specialised training exercises each month.

  • Physical Training: such as intensive activities such as marches, riding, swimming to build physical strength and stamina.
  • Weapons & Armour Training: to ensure soldiers were familiar with their equipment. Soldiers would practice against wooden dummies to perfect their form and build strength. Soldiers would learn how to use swords, javelins, spears, bows, slings and artillery equipment. They would also be taught to use their shield as a weapon with which to strike the enemy with. Additionally, the weapons and armour used for training were made of wood and heavier than the actual equipment used in battle.
  • Strategy & Formation Training: to ensure soldiers interacted and worked together to maximise the effectiveness of the legion. This organisation and efficient chain of command gave Rome a significant advantage over less organised forces.
  • Discipline: training was used to condition soldiers to the Roman military way of life. It ensured soldiers followed orders when they were told to do so.

If a legion had many new recruits, a general would often take them into minor conflicts to give them an experience of battle before starting on the army's main campaign objective.

The training of horses was also very important. Horses were used not only in combat but also for supplying the front lines with necessary supplies and sending messages. It was vital that horses were able to: withstand the weight of an armoured cavalryman, remain calm in battle, to swim across shallow rivers, jump over obstacles and small defences.

Make-up of the Army

The Roman army consisted of the legions, auxiliaries, and other allied forces. The Roman legions were exclusively made up of full Roman citizens. The auxiliaries, on the other hand, consisted of men from the provinces.

24 CE 130 CE 210 CE
Legions 125,000 155,000 182,000
Auxiliaries 125,000 218,000 250,000
Praetorian Guard 5,000 8,000 15,000
Total Soldiers 255,000 381,000 447,000
Roman Legions

The Roman legion was the main body of the Roman army. Following the Marian reforms in 107 BCE, each legion would consist of 4,800 infantrymen.

  • Each legion was split into ten cohorts of 480 men each.
  • Each cohort was split into six centuries of 80 men each.
  • Each century was split into ten contubernia of 8 men each.
  • Each legion was accompanied by a cavalry unit of 300.

Before the Marian reforms, the Roman 'legion' looked somewhat different. The history of the legion can be split into three eras: the early period, the manipular period and the cohortal era.

Read more about the Roman Legions.

Roman Legion Broken Down Roman Legion Broken Down
Roman Auxilia

The Roman auxilia was established by Augustus around the beginning of the Roman Empire (30 BCE-ish). It only took fifty years for the number of soldiers in the auxiliary ranks to surpass the legions. This trend continued, and during the mid/late Roman Empire, there were far more auxiliary soldiers than there were legionaries.

The Roman auxiliaries were made up of men who did not have full Roman citizenship. Most auxilia units were paid less than legionaries, receiving 750 sestertii per year (a sixth less than legionaries). Once a soldier completed his 25 years of service, he would receive full Roman citizenship for him and his family.

The auxilia were essential to the Roman army as they provided specialist units, including cavalry and ranged units. They received a similar level of training as the legionaries and were well equipped to deal with the hardships of Roman military life.

Read more about the Roman Auxilia

Allied Forces

Alliances were an important part of Rome's territorial growth. Early alliances with other cities and towns in Italy allowed Rome to gain dominance over the Italian peninsula. During the late Roman Empire alliances grew even more important. The Senate signed treaties with more and more 'barbarian' tribes in an attempt to protect Rome's vast borders.

A foederati was a treaty between Rome and a tribe requiring them to fight with Rome. Unlike the auxiliaries, these units would fight under their own commander. An example of this came after the battle of Adrianople in 378 CE, where the Romans were unable to beat the Goths in battle and instead offered them land in Thrace if they would fight with Rome against future enemies.


The Romans were reluctant to recruit mercenary forces. One exception occurred during the Punic Wars in the third century BCE, when the Romans employed around 15,000 Celtiberians in Hispania. However, these mercenaries quickly betrayed Rome and joined the enemy. This didn't do much to encourage Rome to employ more mercenary forces anytime soon. It wasn't until the third century CE that Germanic tribes would be hired to protect the Roman Empire's borders.


The Roman army was a highly organised force with a well-defined hierarchy. Officers had total command of their underlings and soldiers knew exactly what was required of them on a daily basis.


As stated above the Roman army had a very rigid and well set out hirearchy. This meant that each man knew who he reported to and who reported to him.

Roman Legion Hierarchy Roman Legion Hierarchy

Generals and Legatus

Throughout most of the Roman Republic (509 BCE to 107 BCE), the two consuls of the Roman Senate would each be granted two legions to command. These two men had total control over Rome's armies. However, as time passed and Rome's territories grew, more soldiers and legions were required. Thus there was a need more generals. To take command of a legion a man would have to hold the position of praetorian rank or higher in the Senate.

The man in charge of a legion was called a legatus. This position afforded the man an enormous amount of power: they would receive large amounts of booty won on campaign. Additionally, they had absolute authority over their men and civilians, being able to issue any punishment they saw fit.

As a result of all this power, Augustus restricted the time a man could serve as legatus to two years. This was later extended to four years and in many cases, the legatus would serve indefinitely.

Senior Officers

Below the legatus there were seven senior officers. These officers were often appointed by the legatus based off recommendations from other high ranking Romans.

  • 1 Tibunus Laticlavius (Second in command)
  • 5 Tribuni Angusticlavii (In charge of two cohorts each)
  • 1 Praefectus Castrorum (Camp prefect)

The tibunus laticlavius was the son of a senator. This position was one of the first steps in his political career which would more often than not take him back to a life in Rome.

Next in command were the five tribuni angusticlavii. These men were from the equestrian class and were each in charge of two cohorts.

The praefectus castrorum was the camp-prefect. He was in charge of discipline and overseeing construction projects. This was the highest position a normal Roman citizen could reach. He would often be promoted from the position of primus pilus the most senior centurion of a legion.

Field Officers

For each legion, there were sixty centurions, who were each in control of 80 men. Each centurion was responsible for training, discipline and other daily activities. The centurion fought on the front lines alongside his men and was critical in maintaining the order and formation of soldiers.

Centurions earned considerably more than the standard foot soldier, they had their own separate quarters on camp and could also take their own slaves with them on campaign.

Below the centurion was the optio, the second in command of a century. He would take control if for some reason the centurion was incapacitated. The optio was also responsible for ensuring the centurion's orders were carried out. His pay was double that of a standard legionary. He would also likely be promoted to centurion later on in his career.

Non-Commissioned Officers

The non-commissioned officers were legionaries who held specialised tasks which allowed the legion to function normally.

A soldier in this position would be known as an 'immunes'. They would have performed any number of jobs, for example, carpenters, stone masons, musicians, etc. While these soldiers did not receive higher pay, they were exempt from performing the more mundane tasks other soldiers had to do. To be eligible for this role a soldier would either have to be promoted by their centurion after several years of service. Alternatively, if when a soldier enlisted, they had a letter of recommendation from a highly respected Roman citizen they would often be immediately appointed to one of these positions.

Once a soldier had served as an 'immunes' for several years and had shown potential and ambition they would be promoted to become a 'principales'. A soldier of this rank would often take control of training and other positions of responsibility, as well as a nice pay rise.


The infantry was the backbone of the Roman army. At the beginning of the Roman Empire (27 BCE) the infantry of Rome numbered over 200,000 strong.

Up until 315 BCE, the Roman army used the phalanx in battle, based off the Greek style of warfare. However, during the Samnite Wars, this formation had to be abandoned as the terrain was rough and not suited to the phalanx formation. Instead the 'maniple' was adopted. In this new system, the Roman infantry consisted of velites, hastati, princeps and triarii.

  • Velites - light infantry who would participate in the skirmish before the battle began. Would launch projectiles at the enemy. They were also equipped with a short sword for hand to hand combat.
  • Hastati - medium infantry, late teens/early twenties with little experience of combat before. The front line of infantry, equipped with a short sword (gladius), several spears (pila) allowing them to launch their projectiles before hand to hand combat commenced.
  • Principes - heavy infantry, soldier in their late twenties with considerable experience. The second line of Roman infantry, equipped with a sword (gladius) and better armor than the Hastati.
  • Triarii - heavy infantry, in their thirties/forties with the most experience. The final line of Roman infantry, equipped with the best weapons and armor.

In 107 BCE, under the Marian reforms the 'maniple' was abandoned in favor of cohorts. This was the modern Roman army which most people are familiar with. The infantry was standardized with identical equipment and training. Each legion now consisted of 4,800 infantrymen.

The legion was also supported by auxiliary infantry, they were equally capable on the battlefield as the legionary infantry. However, they were often deployed on the more vulnerable wings in battle.


The Roman army heavily relied on its infantry for military success. However, the infantry was also supported by a small contingent of cavalrymen. During the Roman Kingdom and the early Roman Republic, only the wealthiest Roman citizens were eligible to serve as cavalrymen. There would usually be 300 lightly armored cavalrymen (equites) accompanying an infantry force of around 4,200 men.

During Rome's expansion into Italy, it relied on its allies to provide a cavalry force.

After the Marian Reforms (107 BCE), the army was organised into legions which were accompanied by a similar amount of legionary cavalry.

In roughly 30 BCE, Augustus founded the auxilia. It would be from here that much of the Roman army's cavalry forces would be raised. Specialised cavalry units such as horse archers would be raised from the eastern provinces Armenia and Anatolia.

Read more about Roman Cavalry.

Projectile Units

A wide variety of ranged units were utilised by almost all armies of the ancient world. Whether they were archers, slingers, javelin throwers or artillery units they were all integral parts of ancient warfare. Before the battle commenced, ranged units would fire volleys at the enemy to soften up the opposition's infantry.

Between 315 BCE and 107 BCE (maniple era), the front line of heavy infantry, the Hastati, would carry pila to launch at the enemy before engaging in hand to hand infantry combat. This tradition also continued after the establishment of the auxilia infantry. These units would carry projectiles to launch at the enemy.

During the Roman Empire, many of Rome's ranged units were recruited from the provinces. Archers were recruited from Syria, Crete, and Thrace and slingers from the Balearic Islands. By the end of the second century CE, 10% of the Roman auxilia were ranged units (18,000/180,000).

Rome's auxiliary ranks also boasted mounted horse archers recruited from the eastern provinces, Armenia and Anatolia. These units would ride into range of the enemy and fire a volley of arrows at the enemy and then retreat before they could be hit.

A common tactic used by these units was the 'Cantabrian circle'. The ranged horse units would make a single file rotating circle in front of the enemy. The cavalrymen nearest the enemy would launch their projectiles resulting in a continuous fire on the enemy. The horsemen would be difficult to hit due to their constant movement. This tactic would often frustrate the enemy and disrupt their formation.


Artillery was commonplace in the Roman army, whether it was used against besieged cities or soldiers on the open battlefield. Much of Rome's knowledge of artillery came from the Greeks.

These machines were too bulky to transport fully assembled. They would be dismantled and then be re-built at the battlefield. The range of some of Rome's larger artillery machinery was (?500?) meters. However, it was only accurate when within a range of 250 meters or less.

Types of Roman Artillery:

  • Ballista Built from wood and held together by iron plates. This torsion powered artillery would fire bolts or stone shots across the battlefield. The ballista was very accurate and could be used to target individuals. While a projectile fired from a ballista could travel up to 450 meters its effective range was much shorter.
  • Scorpio The scorpio was an incredibly accurate piece of equipment. It was small and could be operated by a single man. It was essentially an early crossbow. It was highly effective within a range of 100 meters but could be fired over a distance of up to 400 meters. A skilled operator could fire three to four shots per minute. With sixty scorpio per legion they could fire over 200 bolts per minute at the enemy.
  • Onager The onager was essentially a catapult, used for attacking forts and towns. They were very large and bulky and would not be deployed on the open battlefield due to lack of mobility. They would launch large stones.
Roman Artillery Roman Artillery

Each Roman legion would be equipped with roughly seventy units of artillery. Vegetius wrote that each cohort would carry an 'onager' while each century would be equipped with a 'scorpio'.

In some instances, Roman artillery would not be able to break through well-fortified stone defenses. In this case, onagers would be used to destroy towers which the defenders were using to rain down projectiles on the advancing Roman forces. This would provide enough cover to mount ladders onto the walls allowing the breach of the settlement.

On the open battlefield, it was the ballista and scorpio which were used to gain an advantage. These would be utilised to achieve the following objectives:

  • Guard against enemy flanking maneuvers.
  • Protect strategically valuable positions on the battlefield.
  • Fire into enemy lines to disrupt their formation ;& organization.

Naval fleets would often be equipped with artillery that would be used to damage enemy ships before close quarters combat.

Weapons & Armour

The Roman army used a wide variety of weapons and armour over the entirety of its existence. The auxilia had a diverse selection of units whom each used their own specialised weaponry and armour. This all goes to say that this subject is a little more complex than what one would first think.


The weapon of choice of the Roman legions was the gladius, a short sword that was around half a metre in length. This weapon was very good for thrusting into the enemy as it was double sided. It was used during the later Roman Republic and throughout most of the Roman Empire.

A pilum was a javelin which was carried by many of the frontline infantry units. They would launch it at the enemy before engaging in hand to hand combat.

A pugio (dagger) was carried by all legionary infantry. It was around twenty centimetres in length and would be used in very close quarters when a soldier was for whatever reason unable to use his gladius.

Read more about Roman weapons.

Roman Weapons Roman Weapons

Armour and Clothing

What armour a Roman soldier wore would depend largely on his function. Roman legionary infantry would be equipped with a helmet, body armour, shield and greaves. Clothing varied based on where a soldier was located. Wool was commonly used in all clothing used by Roman soldiers. Clothing would include a tunic, cloak, padding, scarf, shoes and accessories.

Read more about Roman armour and clothing.

Strategy & Tactics

There are three levels of military strategy: Grand strategy which is the overall objective of a campaign. Strategy proper which is concerned with how the army funtions in order to achieve the grand strategy. Finally, operational strategy, which is how smaller groups within the army (i.e. a cohort) interact in order to achieve strategy proper.

A stratagem was a trick which aimed to outwit the enemy to gain an advantage. A senator named Frontius wrote four books regarding stratagems. He distinguished between three types of stratagem:

  • Gaining an advantage before the battle
  • Hiding your true intentions
  • Planting false information

An example of a stratagem is an ambush. Hannibal executed this with perfection at the Battle of Lake Trasimene. He left his main camp exposed giving the Romans an opportunity to strike. The Romans marched across the shore of the lake. However, the previous night Hannibal had deployed soldiers behind the hills. When the time was right these men came pouring over the hill pinning the Roman soldiers against the lake. Hannibal won an overwhelming victory.

Psychology of the Roman Soldier

The psychology of soldiers was critical for Roman military success. Creating an environment to nurture the state of a legion's psyche was critically important and would directly impact the outcome of a campaign. There are numerous potential influencing factors:

  • Weather and climate
  • Exhaustion
  • Marching long distances
  • Sleep
  • Access to food and water

Fear was a large factor in a soldier's decision-making process, and generals would go to great lengths to ensure their soldiers feared them more than the enemy.

For example, when Crassus' soldiers fled from a battle during Spartacus' slave uprising in 71 BCE, he punished them via decimation. Soldiers were split into groups of ten men; they would each draw from a bag of ten stones (nine white stones, one black stone). The soldier who drew the black stone was clubbed to death by the other nine soldiers. Thus ensuring that the remaining soldiers wouldn't disobey orders again.

Life of a Soldier

The life of a Roman soldier was certainly not easy. From the day a soldier enrolled in the Roman military he knew he had a tough next twenty-five years ahead of him. However, this was not without its reward and there was plenty of motivation to put some armour on and fight with the Roman army.

Daily Routine

The daily life of a Roman soldier was tough and not all that exciting. A majority of a soldier's time would be spent: training, marching or completing daily tasks.

  • Collecting food, clean water and firewood
  • Cleaning (armour as well as other facilities)
  • Training
  • Guard duties
  • Specialist duties (accountants, architects, engineers, smiths, etc.)
  • Construction projects
  • Military expeditions
Career of a Senator or Equestrian

Political careers in Rome would start with military experience. It was necessary for members of the senatorial and equestrian ranks to hold positions in the army before being appointed to more senior positions in Rome and in the provinces. Young budding politicians would hold the position of 'tibunus laticlavius', second in command of a legion, for one year in their early career. He would later take up the position of 'legatus' for a period of about three years.

Career of a Soldier

Most soldiers who joined the Roman legion would remain a basic infantryman for the twenty-five years they served for. However, some would rise through the ranks of the legion.

  • The first big promotion was to the position of optio, second in command of a century behind the centurion. A soldier would have to have provided several years of exceptional service before being promoted to this position.
  • The next step would be for the optio to be marked as 'optio ad spem ordinis', meaning that when a centuriate's post became available, they would be immediately promoted. Beyond this, it became tough to rise further.
  • If as a centurion they provided exceptional service, they could be promoted to a centurion of the first cohort. This had a couple of benefits, namely, double pay and prestige.
  • After several more years of exquisite service, they could be promoted to 'primus pilus'. This was the highest ranking centurion in a legion. The 'primus pilus' received double pay of other centurions in the first cohort.
  • The highest position available to standard Roman citizens was 'praefectus castrorum'. To attain this position, a soldier must have held the post of 'primus pilus'.

Roman soldiers received different pay based on their rank and specialities, various deductions would be taken from a soldier's pay for food, clothing and armour. Soldiers were paid on the first days of January, May and September.

  • First Centurion of the first cohort: 54,000 sestertii (Same as sixty legionary infantrymen)
  • Centurions of the first cohort: 27,000 sestertii (Same as thirty legionary infantrymen)
  • Centurions: 13,500 sestertii (Same as fifteen legionary infantrymen)
  • Legionary Infantry: 900 sestertii
  • Auxilia Infantry: 750 sestertii

On joining the Roman army, a soldier received 300 sestertii reward. Likewise, when a legionary infantryman finished their twenty-five years of service they would have received a bonus of 12,000 sestertii (This would have been significantly more for officers).


There were many rewards available for those serving in the Roman army. One of the most important was Roman citizenship for those who did not have it. This was the main motivation for many men when deciding to join the Roman auxilia. Other rewards included:

  • Promotion
  • Bonuses
  • Booty
  • Military decorations
  • Additional rations

If a soldier completed his military service, he received 'bona castrensia', the wealth he had amassed over the many campaigns he had served in throughout his career. Additionally, a plot of land for farming in one of the provinces of the Roman Empire.

Punishment & Discipline

Once a soldier had sworn the military oath, he sacrificed his civilian rights and was under the rule of his legatus. This meant that if he deviated from his commands he would be disciplined as his legatus saw fit. These punishments would be harsh to ensure the soldier would not re-offend.

It was vital that Roman soldiers feared and respected their legatus more than the enemy. Thus generals would go to great lengths to achieve this. During the Roman Republic, Titus Manlius Imperiosus committed his son to death for disobeying his orders.

The Romans had well written out punishments for each crime. For example, they distinguished between desertion and defection (Defection was punishable by burning or impalement, a more severe penalty than for desertion). If a soldier did escape the grasp of the Roman army he would have several choices: head to Rome or another corner of the Roman Empire where he was unlikely to be recognised. Alternatively, they could join a gang of bandits.

Pay and ration related punishments

  • Pecuniaria Mulcta - pay deduction or fine
  • Gradus Deiectio - demotion to lower rank
  • Prohibition of grain rations forced to eat barley
  • Confiscating personal items

Corporal punishment included

  • Castigatio - being struck by the centurion
  • Being flogged or whipped

Other minor punishments

  • Missio ignominiosa - dishonourable discharge
  • Militiae mutatio - given more or worse daily tasks

There were two severe punishments available to officers. The first being 'fustuarium' which was the punishment for desertion. The guilty soldier would be either beaten or stoned to death by the soldiers he endangered. However, if the soldier managed to escaped he would not be chased down instead banished.

The second punishment was decimation whereby a group of men who deserted their positions would be split into groups of ten and forced to draw lots. One of the ten would be beaten to death by the others.


A soldier's diet would have consisted of a lot of wheat and barley. However, they would have had access to a wide variety of foods depending on where they were located. This could include bread, cheese, oil, fruit, vegetables, meat, fish, spices, salt, beer and wine.

A Roman soldier would consume around 3,000 calories per day. However, this would depend on whether there was a shortage or surplus of food in a region. Soldiers would also drink between two and ten litres of water per day, depending on the climate.

The amount of food required to sustain a single army was monumental, requiring extensive agricultural efforts. Crops would regularly fail and this would directly affect Rome's armies, as rations would have to be cut. Additionally, a Roman army would travel with a large amount of animals who would require large amounts of food and water also.


There were several types of discharge. The first was 'honesta sissio', or honourable discharge which was awarded once a soldier completed their service. Secondly, 'causaria missio', which was awarded to soldiers who had been injured too severely to finish their full service. They would receive a bonus based on the amount of years and campaigns served while in the army. The final type of discharge was 'ignominiosa missio', a dishonourable discharge in which the soldier would receive none of the benefits he had been amassing over his career.


There was always a chance that a soldier would not make it through his twenty-five years of service. Death in battle was uncommon; if the army was successful, then casualties would only amount to about 5%. If defeated this casualty rate would only rise to around 15%.

The biggest killers in the Roman army were infections, diseases and illness. Other common killers were starvation when supply lines failed and also exhaustion. Additionally, exposure to extreme climates resulted in death in some cases.

Types of Warfare

There were many different arenas of war, some which Rome excelled in and others which they tolerated. The arena of choice for the Roman legion was an open battlefield where well-rehearsed tactics and formations could be executed with crushing effectiveness. However, Rome's enemies weren't always too accommodating for Rome's preferences and would force conflict to take place in a wide array of scenarios.


Some of ancient Rome's most humiliating military defeats came at the hands of ambushes, for example, the Battle of Trasimene (217 BCE) and the Battle of the Teutoburg Forest (9 CE).

Maps would be studied very carefully when selecting the army's route to choose the most secure route with the least chance of ambush. The army would also march in an order which was prepared to defend against surprise attacks.

Ambushes were considered dishonourable and cowardly in the eyes of Romans. As a result, Rome rarely ever used the tactic against enemies. However, Tacitus wrote about an ambush set up by Aulus Caecina in 69 CE at the Battle of Bedriacum. He positioned his auxiliary forces in the woods next to the road while using his cavalry to draw the enemy down the road into the trap.

Open Warfare

Ancient Rome's preferred method of warfare was on an open battlefield. Here the Roman army could utilise the full power of the legions to devastating effect. In this scenario, Rome rarely ever lost a battle.

Town Warfare

Battles fought in towns and settlements were uncommon during the ancient era. The battle would be won or lost after the attackers either succeeded or failed in taking the walls.

However, there are a few examples of battles taking place in the streets of a settlement. These would be very bloody affairs with high amounts of casualties. Due to the usually narrow streets, cavalry and projectile units would be rendered irrelevant. These affairs were very messy; often civilians would be slinging debris onto the enemy from the rooftops.

In the narrow streets, highly trained infantry would be deadly as they could not be outflanked. This allowed skilled infantry to kill many more enemy soldiers than they lost. The enemy often had nowhere to run which meant they were essentially cattle in a slaughter house.

Guerrilla Warfare

Enemies of Rome knew that they were outmatched on an open battlefield. Subsequently, they refused to meet Roman legions in the open, instead electing to harass and impede the Roman armies as much as possible.

This was done by launching fast strikes against Roman soldiers before quickly retreating into dense forest where they could not be followed. Additionally, attacking isolated Roman units and attacking poorly defended settlements.

To counteract guerrilla tactics, Rome built various defendable fortifications, for example, Hadrian's Wall.

Siege Warfare

It was important for a general to understand the nuances of siege warfare.

When a defender was besieged, the attacking commander would first send terms to avoid a potentially long and resource draining conflict. If these terms were rejected, then it would be up to the attacker to either wait and drain the defender of resources or overcome the defences.

The attackers would build fortifications of their own when besieging a settlement. A trench would be dug around the settlement. A ridge would be constructed behind the trench with a wooden palisade on top. This prevented resources and intelligence being taken into the town. Additionally, this provided protection against counterattacks from the defenders.

Various devices would be used to help provide extra defence. Tribuli were spiked metal tetrahedrons which were thrown on the ground. These would penetrate the feet of anyone who walked over them. Large wooden stakes would also be placed to slow down the advance of the enemy.

If the attackers decided to take the settlement by force, they would have several choices. They could attempt to break down either the walls/gates, alternatively, they could ascend the walls. Various tools and technologies were available for each of these options:

Methods of Ramming Through the Gates

  1. Battering Ram (Aries) - The battering ram was quite obviously used for battering the besieged gates open. It would be placed on wheels and moved into position by the attacking soldiers. It would often be covered in an animal hide to protect it from fire and other projectiles.
  2. Testudo Arietaria - This would protect the soldiers moving the battering ram into position. It was a large shed-like contraption which was 15 meters long, 10 meters wide and around 6 meters tall. This shed would be covered in animal hides to protect the soldiers and ram from arrows and fire.

Methods of Destroying Walls

  1. Tunnelling (Cuniculus) - This is one of the most effective ways of toppling enemy walls. By tunnelling underneath the walls and then settling the tunnel's supports on fire to collapse the tunnel. Often bringing down the wall above it.
  2. Catapults (Onagers) - Onagers were large catapults used to smash through enemy walls, as well as doing damage to buildings beyond the wall. Read about onagers and other artillery used by the Roman army.

Methods of Climbing the Walls

  1. Ladder - this was a good option if time was limited. They were very quick to build. However, they provided very little protection and would result in higher loss of life for the attackers compared to other siege warfare practices.
  2. Siege Tower - these were large towers which were either as tall as the walls or higher. Constructed with timber they would commonly be covered in an animal hide to prevent fire damaging the structure. Near the top, there would be a drawbridge which would be lowered onto the wall. Sometimes there would be a platform on top of this which the attackers could use to shoot arrows at the defenders.

    The most effective method for the defenders when faced with siege towers was to destroy them before they got to the walls. There were a couple of options: firstly, the defenders could dig hidden holes where they believed the attackers would use the siege towers. If the siege tower fell into the hole, then it would be useless. Alternatively, large bolt-launching machines would be used to damage the siege tower's infrastructure.

    For a siege tower to work, it would have to be a perfect size. The attackers had a few methods for measuring the height of the enemy's walls. The first method was using the shadow cast by the wall to calculate the necessary height. Secondly, an arrow with a long piece of string attached to it could be fired at the top of the wall. Pythagoras' theorem could then be used to calculate the height of the wall.

Medical Practices

During the Roman Republic, medical duties were bestowed on common soldiers who would operate as 'medici'. The knowledge of medicine was limited, and so was the treatment. Many soldiers would die through illnesses and infections.

At the start of the Roman Empire, Augustus organised a specialised medical branch of the army. The numbers of medici were increased to better deal with casualties. Around the first century CE, there were roughly ten medici per legion. These men would have likely had a history in medicine before joining the army but would also receive further training after enlisting.

The number of hospitals in military forts and settlements during the Roman Empire also increased. These hospitals would have had sixty small rooms, one for each century in a legion. Each room would have been able to hold between two and four people at a time.

It would be the legatus' responsibility to prevent infections and disease from spreading through the army. Camp would not be set up where there was no access to fresh drinking water or other potential threats. A soldier's daily routine was also organised to keep him in the best physical shape, with regular exercise and hygiene practices.

Roman Navy

The Roman navy mainly played a supporting role in many of the legion's land based campaigns.

However, during the Punic Wars, Rome's naval capacities were increased dramatically. From a fleet of fewer than twenty vessels, Rome's navy turned into a force which challenged and overcame the largest naval force in the Mediterranean.

Perhaps the most famous naval battle of Roman times came in 31 BCE, at the Battle of Actium. Fought between Octavian and Mark Antony it resulted in the end of the Roman Republic and the start of the rule of emperors.

Rome's ship of choice was the trireme. It was a very fast and nimble warship which the Romans had adopted from the Athenians. Called a trireme because of the three rows of oarsmen that would operate it. Each trireme would have around one-hundred and eighty rowers, allowing the vessel to reach speeds of ten knots (18 kilometers per hour).

The Roman navy was not a glamorous career choice. It would often be those who were not eligible to join the Roman army that would be forced into a life on the seas. Each man would have to serve for a total of twenty-six years before retiring with full Roman citizenship.

Read more about the Roman Navy.

Roman Trireme Roman Trireme

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