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roman army

A picture of the Roman Army


Titus Livius known in English as Livy (1st C BC) and the Greek writer Polibius are perhaps the best literary source regarding the Roman army, wars and battles of the earliest history of Rome: They were more like cattle raids and skirmishes against the tribes and settlements in the vicinity of the Tiber. There would have been some pitched battles although they would be more the exception than the general rule. The armies and troops involved were closer to bands of warriors than the Roman army we have in our collective imagination. Such groups would include a leader – a member of the local nobility ("Patricians") – together with supporters, family members and others belonging to his family group ("gentes"). We have a description of this in Livy Bk2, 49.

A step closer to the developed Roman army we know was achieved around the 6th century BC, during the reign and reforms of King Servius Tullius. Servius’ reforms included military reform and the census: the latter was clearly necessary to enable management of public affairs such as voting and taxes but also to facilitate the creation of a military force built around the city’s citizens because the census enabled citizens to be subdivided into classes of wealth.

This link between voting rights, wealth (land ownership) and military duty was highly significant in that it constituted the basis the Roman army and Roman citizenship: those with a right to vote and wage war were those who had property to defend and an interest in disseminating Roman law.

The old system based on farmer-soldiers was eventually doomed to fail but the ancient Romans were quick to adapt their approach. Factors forcing change were:

    1. Farming requires its own particular seasons of work in order to produce food and income: wars on the other hand are not intrinsically seasonal. The "war season" was an early concept which eventually fell out of use: Imagine the strategic advantage of being able to wage war when your enemy is forced to tend to the land lest he be left with no winter food…..
    2. Wars were increasingly long in duration and far from home.
    3. Territorial expansion, increasingly extended borders and increasingly tough enemies in extended wars such as the Samnite and Punic wars implied an increasing need of men to fill the file and ranks of the Roman army.
    4. Territorial expansion meant greater overall wealth for Rome but this wealth was increasingly concentrated in the hands of a few, whilst the broader population was relatively impoverished. This meant that the number of people falling into the various census classes was changing greatly with many actually falling off the bottom of the scale and forming part of the increasingly large proletariat.
    5. The relative lack of social and military organization during the 5th century meant that many of the wars undertaken were inconclusive and generally less fruitful in terms of booty and land with which to pay out rewards. The difficult economic situation lead many to incur debts and in need of a means to find income.

Result: The recruitment approach began to change around the 4th century when Rome began to pay its soldiers so as to enable them to serve a longer period of military service as well as progressively lowering the wealth individuals were expected to have in order to form part of the various classes of soldier. In 405BC the consuls Albinus and Camillus, for the first time, conscripted 2000 men who lacked the wealth requirements for service in the army.

In terms of the Roman army, the issue of war booty distribution (or lack thereof) had various effects:

    1. Lack of wealth distribution caused great social upheaval within Rome and it is curious to note that the Gracchi brothers, upholders of the plebeian rights to more equal land distribution had close family ties with some of Rome’s greatest generals against Carthage. Their reforms found great opposition from the nobility. From a practical army enlisting point of view the heavy imbalance in wealth distribution forced a shift in the census parameters by which individuals were measured for enlisting in the army – this was brought to its natural extreme with Marius’ army prototype in 107BC made of fully professional soldiers driven more by the promise of personal gain in the booty than by the traditional honour of representing their country.
    2. Outside Rome, the imbalance engendered the Social Wars during the years 91-88BC – many of Rome’s Italic allies rebelled against the unfair distribution of wealth (they had been driven to poverty) and created an alliance amongst themselves against Rome. Several years of war and battle saw a slow but progressive Roman victory, but nevertheless the indomitable Samnites held out and managed to force Roman law for greater equality – winning Roman citizenship and voting rights for themselves and the allies (allies = "Soci" hence "Social" wars). Ie significant social changes ensued in Rome itself.

According to the writer Polibius we learn that in the early days all citizens within the ages of 17 and 46 years of age owning over 11,000 aes were obliged by law to attend the annual military conscription process known as "dilectus" on the Capitoline hill. When times became harder or need for men grew then the minimum wealth hurdle was reduced. The number of years of service for each man was limited to something in the region of 16 as foot soldier and 10 as cavalry. As the years progressed the conscription rules were changed and refined, but always with the concept of maximizing the use of men in the army whilst also placing an ultimate pensionable limit on their service. The longest period of consecutive service was placed at 6 but this didn’t mean prevent you from being called back to service for many more campaigns or periods of annual service.

A definitive shift came about with Gaius Marius around 107BC; himself a man of the people who had made it to the top of public ranks, strongly supported into Consular office by the Plebeians against the Patrician noble classes. Rome had seen a number of relatively ineffectual years of campaigning in Africa and more importantly was threatened by Germanic barbarians invading Italy from the north. Marius broke all conventions by taking a personal unilateral initiative in conscripting and creating an army made up purely of paid volunteers from the lower classes: individuals who were driven almost entirely by personal interest in the booty they would receive rather than by nationalistic sentiment. This large mass of professional soldiers, motivated almost entirely by personal gain was to change the future shape of ancient Roman politics as they were the mainstay of any figure wishing to clinch power. It is hardly surprising that the shift came about just when the civil wars were about to begin.

Notwithstanding the change to a professional army, the tight link between civilian life and military life remained intrinsic to the Roman military system, especially in the early years of the Roman conquest of Italy, but also through the republican and imperial periods: The highest military ranks were held by high ranking magistrates such as Consuls and Praetors who had been voted into office by the public at large. The link between military and civilian spheres became even stronger when the supreme commander of military power was the emperor himself and vice-versa in the latter years of the empire the emperor was often a person who held military command. Good examples of this are emperor Vespasian (who turned out to be an altogether good emperor) and emperor Constantine. There were of course bad examples also.

Difficult political situations were frequently caused by the emperor’s or commanders need to reward his veteran soldiers by giving them some land to farm and live on. An interesting example of this was Augustus (then known as Octavian) who had the makings of a military revolt on his hands in Italy whilst having to fight against Marc Anthony and Cleopatra in the eastern Mediterranean. Clearly this land was frequently procured by confiscating the land and belongings of those who had been vanquished.

The Socii - Romes Allies

To the number of soldiers coming from Rome’s citizens we have to add at least an equal number of legionaries provided by Rome’s allied or vanquished populations. The general rule was therefore that the Roman legion would be more than doubled in size by a supporting wing ("ala") of allied militia. Allied cavalry support was about three times the Roman cavalry – ie a legion, which generally included 300 Roman cavalry, would be supported by a further 900 allied cavalry.

The forces and officers provided by the socii were commanded by a number of Roman officers nominated by the consuls.

Size of the Roman army:

It is estimated that the Italic allies of Rome could provide something in the region of 250,000-300,000 men including some 35,000 cavalry. At the time of the Punic wars against Carthage and general Hannibal Rome came to mobilize as many as 25 legions: 120,000 men, which when coupled with allied forces would have added to something akin to 250,000 men. Livy tells us that the devastating loss at the battle of Cannae against Hannibal cost Rome a full 50,000 men , but clearly whilst a large number, this was only a fraction of the total number of forces available.

Shape of the Roman Army

In order to have a clear understanding of how the Roman army changed in shape and form, it is also necessary to appreciate how Rome’s wars and expansion from Rome, across Italy, into Sicily and then across the Mediterranean: The changing needs of terrain, distance, logistics and duration, not to mention the changing types of adversary meant that the Roman army had to adapt and change in form and organization.

Verious examples of Roman adaptability and readiness to assume winning formulae include:

    1. Shift from the greek type compact Phalanx to the more widely spread manipulus and legions. This was likely a gradual shift, but likely around the time of the Samnite wars in the 4th century BC (Sallust – Bellum Catilinae bk 51)
    2. Around this period we also see the possible introduction of a professional army model – a very basic pay enabled the soldiers to stay away from their land and work and to be motivated by a cut of the booty.
    3. Adoption of various types of armament such as the Hispanic gladius as a sword and the ply-wood scutum rather than the hoplitic round shield
    4. Building of a navy from scratch, adaptation of the enemy’s (Carthaginian) ship type and in a short time actually beat the Carthaginians with it (various battles around 260-241BC).

The Romans of the kingdom and early republic learned from the neighbouring Etruscans how to use the phalanx, similar in style to that of the Greeks who had their colonies to the south of Rome. The Roman legion of this period was built of Roman citizens sufficiently rich to pay their own weapons and armor: The census introduced by Servius Tullius described above allowed the construction of the phalanx according to citizens of given levels of wealth and corresponding personal armament:

"Fulvosque lupi de pelle galeros"

Formations of the Roman army

These different classes of soldier were laid out in lines, like a wall, facing the enemy, starting with the heavily armed soldiers as in the order described above. Each line broken up into 10 building blocks or units called "manipulus" (Other accounts eg Polibius suggest 15 manipuli). The following row would be lined up behind the one in front but with the manipulus units placed immediately behind the gaps of the preceding line: rather like a chequers board. The cavalry would be laid out to the sides.

Hastati: Principes : Triarii : Velites (spread out across the others or as rearguard) : Equites (on the two sides).

However the standard layout was not the only strategic approach which could be employed, a variety of shapes were employed according to the nature of the enemy and terrain:

Cuneus (wedge) or Caput Porcinum (pig’s head): The army was arranged in the shape of a wedge to break through enemy lines.

Globus: A circular formation, used most frequently in cases of extremity.

Forfex: A formation like a pair of scissors, likely used if the enemy utilized a cuneus formation in order to limit damages to their own numbers whilst cutting into the enemy formation from the sides.

Pyrgus: A rectangular figure like a tower, with few men in each file (row) and many files.

Serra: An approach by which the foremost manipuli would engage for some time and retreat, allowing another set of manipuli to move forward and engage, until they retreated to be replaced by the first again.

Command of the Roman army

Command of the Roman army can appear a little complex at first but is actually relatively simple. Top level military command was held by the highest public offices: the Consuls and Praetors. The senate provided them with council and support. These public offices were elected each year, and being elected politicians they clearly tended to lack the acumen of seasoned military generals even though, as with all top magisterial positions they had to have undertaken at least 10 years worth of military service, most likely in the cavalry.

During their year of tenure these magistrates were given almost absolute power – hence the need to introduce a check and balance system of having two consuls often from opposite factions, two praetors (later 4), 6 military tribunes etc. The power these men held were symbolized by bundles of rods known as fasces: a symbol of power which had been inherited from the Etruscans in the very early days when Rome was a kingdom.

The chart below breaks ancient Roman military command structure relatively simply:


Unit comanded


General Notes

Dictator Entire Roman army Only in times of great danger the Senate could nominate a short term dictator who was given absolute power. Republican age of Rome.

6 month tenure.

Greater incisiveness in times of great threat.

Cincinnatus was an early example.

Julius Caesar was named "Dictator perpetuum"

Consul Consular army Each year 2 Consuls were elected to govern ancient Rome. They held a form of supreme power. Each Consul had an army. Consular army consisted of 2 legions with their respective alae of supporting forces. Total size was approx 20-25,000 men.

A quaestor would support management of the consular army, rather like a chief financial officer.

Praetor army Lead an army in engagements which didn’t call for a consul. The army led by a praetor would have only 1 legion + ala of socii ie 10-15,000 men. If more armies were required these could be commanded by other magistrates such as the 2 Praetors (eventually 4 praetors each year) or Pro-Consuls called for the need.
6 Military Tribunes Legion Conscription,

Swearing in,

Assign roles in different positions


Health and wellbeing


Two tribunes would comand the legion for two months at a time.

No fixed position within the legion.

Publically elected.

5-10 yrs military experience.

3 Praefecti Ala (supporting troops provided by allies) Roman high command of allied troops. Three men who effectively held high command of allied supporting troops which otherwise had their own local officers, armaments and fighting techniques.
2 Centuriones Manipulus Each centurion commanded a centurio of 60 men, 2 centuries made a manipulus = 120 men. There were 30 manipuli in a legion ie a legion contained 60 centurions.
3 Decuriones Turmae (cavalry) 10 horsemen each = 30 horsemen in a Turma Usually made of aristocracy and people rich enough to have a horse though in later times lost horses would be refunded to the individual by the Roman state.
Signifer, Cornicen,


Century (60 men or 30 men in Triarii) Standard bearer, horn blower, centurion’s aid bringing up the rear.  


Waging Battle in Ancient Rome

When waging battle the lightly armoured Velites would be the ones to open up battle, create some noise and chaos with their slings and would eventually be ordered to fall back through the spaces left between the manipuli of the Hastati and Principes to take their place in rear-guard or amongst the manipuli of heavily armed infantry. At this point the two rows of hastate and principes would spread out to create solid rows rather than the chequered "quincunx" formation.

A quote from Virgil renders the idea (Georg. ii, 279):

"Ut saepe ingenti bello cum longa cohortes,

Explicuit Legio, & campo stetit agmen aperto,

Directaeque acies, ac late fluctuat omnis

Aere renidenti tellus, necdum horrida miscent…."

"Sed quia non aliter vires dabit omnibus aequas

Terra, neque in vacuum poterunt se extendere rami"

The two armies would then close up until they engaged in hand to hand combat: we can imagine that as they advanced the legionaries from the Hastati would wait until the last minute and throw their Pilums in order to disable the enemy’s shields and indeed kill as many as possible before having to draw their swords. Some accounts suggest that a pilum had extremely powerful penetration capability and would often go through enemy shields and kill the enemy soldier. The Roman soldiers would then close in further, drawing the gladius with their right hand; the enemy strikes with a cutting sword blow, the large Roman shields would fend the blow with their metal edge, followed by a sharp thrust of the shield’s central "umbo" into the enemy’s face and a stab into the enemy’s body with the short gladius….

The cavalry would be coming in round the sides, clearly the effect of cavalry work is far more effective when the horse can see space to charge into rather than a compact unit of charging/shouting enemy. Thus the difficulty of cavalry being that of keeping a cold blooded approach and frighten the enemy formation into breaking apart to enable the horse to wedge in, trample and the soldier to swing on those below him.

roman army

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"roman army" was written by Giovanni Milani-Santarpia for - Rome apartments