THE ROMAN MILITARY
The Roman Republic and the Roman Empire together lasted for over one-thousand years,
and at its height, their extensive territories stretched from the Atlantic Ocean in the West, to the
rivers of Mesopotamia in the East, and from the Sahara desert in the South, to the River Rhine in
Northern Europe. The one factor that made this spectacular feat possible was the exploits of the
Roman Military. The military had succeeded in their expansion campaigns and had successfully
defended the borders against foreign invaders for centuries. The fact of the matter was that the
Roman Military was the deciding factor in any successes or failures the Roman state incurred,
and at its most basic element, it was ultimately the successful strategies and doctrines of the
Roman Army that made their victories so pervasive. This paper will trace the development of
the military from the early Roman period through the Marius' reforms, with an emphasis placed
on the primary battle formations and tactics employed by the Roman Legions.
The early Roman Army was formed under the Etruscan ruler, Tarquin the Proud in the
seventh century B.C.. During this period, the Etruscans fought in the Phalanx formation, with
the primary fighting force made up of native Etruscans. The Romans were relegated to fight as
only skirmishers defending the flanks of the legions, but this would all change under the second
King of the Etruscans Servius Tullius in the mid sixth century.
Tullius' first act was to reorganize the army based on wealth instead of race. Only the
men who owned a certain amount of land were now eligible for military service. Furthermore,
he divided the Army into five classes with each group formed according to their individual
wealth. The richest soldiers formed into eighty centuries, forty of young (ages 17-46) and forty
of old (47-60) called lochoi. This highest class of soldiers were fully outfitted in Greek style
armor. The rest of the men were organized into twenty centuries each and armed and suited
according to their wealth.
The primary formation this early army fought under was the phalanx. The formation was
divided into three different groups of soldiers: the principes, hastati, and the triarii which com-
bined to form the heavy infantry section of the phalanx. Each of these soldiers were equipped
with the hasta long spear, a sword, and fully dressed in armor. Those who could not afford the
necessary equipment were used as skirmishers and armed with a light spears and shield only.
The phalanx legion was generally made up 3000 men and supported by 300 cavalry sol-
diers on the flanks. The men were drawn up into six ranks of 500 men each, which was further
broken down into centuries of 60 to 100 men. The commanding officers of the centuries were
the Centurions, these particular men were, essentially, the backbone of the legions. The phalanx
proved to be a formidable formation under ideal lowland conditions, but its Achilles heel was
that it was highly inflexible in the characteristic broken terrain of central Italy. It proved too
difficult to coordinate movement of the 3000 soldier tactical unit when fighting against the
mobile barbarian opponents, but Rome would continue to use this battle formation up to the
It must be noted that at this particular time, the Roman military was not a professional
army, but rather it consisted of citizen soldiers who were recruited only after a military situation
presented itself. There was no standing army, no pay, and the men primarily volunteered due to
the perception that it was a citizen's duty and a privilege to serve for his state.
In 390 B.C., Celtic warriors advanced into Rome and, subsequently, defeated all Roman
attempts at containing them. They sacked city after city throughout the state, and finally
retreated after a seven month long siege on the capital. It was at this time that the Romans
recognized that a reorganization was necessary if they were to continue to be the continental
power and, consequently, they abandoned the phalanx formation and replaced it with the
Manipular Legion. This new reform has been historically credited to Furius Camillus, but it is
now generally believed that the reform was the product of many years of gradual change
throughout the fourth century.
The manipular legion now consisted of 4,200 infantry and 300 cavalry soldiers, which
was divided into 30 maniples. Whereas before the tactical unit had been the entire 3000 man
phalanx legion, now the tactical unit was the 120 man maniple. Each maniple contained two
centuries of 60 men each. As well, the new formation had the army fighting in waves of three.
The first line were the hastati, the second were the principes, and the third the trairii, with each
of these groups consisting of ten maniples a piece.
Those soldiers who were too young and who could not afford the appropriate equipment
were established as velites. This particular group was the lightly armed skirmishers of the legion
and equipped with only a javelin and sword. The first line of heavy infantry were called the
hastati and was made up of 1,200 men between the ages of 25 and 30. The hastati were armed
with the short cut and thrust gladius sword and two long pila (javelins). Those between the ages
of 30 and 40 formed the 1,200 man principes. This group was armed identical to the hastati.
Any soldiers over the age of 40 were grouped together as the 600 man triarii. These were the
highly revered veterans of the legions and would only be used if necessary. The triarii were
armed similar to the former groups, but instead of carrying a pila they carried long spears.
All heavy infantry were equipped with a small breastplate called a pectorale, bronze
helmets, usually one greave, and a scutum shield. The scutum shield was a very heavy, curved
shield two and half feet wide and four feet long. The shield was not meant to be wielded around
to defend the legionaries, but rather it was generally used during the opening charge to try and
throw the enemy off balance, and, subsequently, the soldier would take a fighting position
behind his shield during combat.
To facilitate interchange amongst the units, gaps were left in between each maniple, and
it was these gaps that made the successive wave attacks of the legion so successful. When the
signal was given, the velites initiated the attack by advancing through the gaps of the heavy
infantry units and when in range of the enemy they would launch a volley of javelins with the
intent to disrupt the enemy formations. After their attacks, the velites retreated back through the
gaps to the rear of the legion. From this point on, the velites were relegated to a reserve status.
The actual pitched battle began with the first line hastati advancing toward the enemy
while they simultaneously clashed their pila against their shields. When the commanders issued
the order, the hastati moved in while launching a volley of pila on the enemy ranks and then
drawing their swords to engage in close order combat. It was this hand to hand fighting that
determined the outcome of the battle, and the Romans were extremely skilled at this art.
If the hastati were unsuccessful, they would disengage and reopen their ranks so that the
principes could now advance. If the veteran principes were also repelled, then the triarii would
engage. If a battle ever came down to the triarii, this would be indicative that the situation had,
indeed, become desperate.
The new manipular legion proved to be quite successful for the Roman Army, for it
allowed them greater mobility, with the capability of enveloping or penetrating the enemy
formations. But it also had its deficiencies as well, for there were now 30 tactical units and with
such a large number it became increasingly more difficult to coordinate them during battle.
The new battle tactics also represented a change in the political realm in the Roman
state. During this period, soldiers began to be paid for the first time, with a Roman soldier re-
ceiving about two obols a day, a centurion about 4, and a cavalryman receiving 6 obols a day.
Despite the new face of the military, there was, as of yet, no professional army, but rather it was
still made up of regular Roman citizens. However, men were now liable for service in at least
twenty campaigns for the state, but were eligible to return home in between. This non-standing
army would present a problem at the end of the second century B.C., for as campaigns became
greater in number and longer, men became unwilling to neglect their farms and businesses.
With the Roman legions engaged in more unpopular campaigns, it became increasingly
more difficult for the state to supply the necessary numbers the army required. At this point, it
was obvious to most that drastic measures would have to be undertaken to rectify the military
system. The option of conscription was revoked due to the massive discontent it would have
created among the people, and with no better alternative to consider, the Roman Army was
really forced to open up the ranks to all free citizens.
The Roman Consul, Gaius Marius has been generally credited with this particular
reform, but it must be noted that actual changes began to be made under Gaius Gracchus. It was
he who was the first Consul to make it substantially easier for non-wealthy Romans to join the
legions, thus, paving the way for the later and more sweeping reforms of Marius.
With the army now open to all citizens who could claim free birth, it was primarily the
poor who rushed en masse to join the Roman military. They saw an opportunity to become
respected war heros, and if for nothing else, they could earn a significantly larger wage. The
reforms strayed even further from tradition with the requirement of a twenty year enlistment
from the men instead of just serving in twenty campaigns. These particular changes in the
military created the first professional army of Rome.
Marius also recognized that the manipular legions were too numerous and proved too
difficult to coordinate during battle, so therefore, a reorganization of the legions themselves
were necessary. His first act was to increase the trairii from 600 men to 1,200 so that they would
equal the hastati and principes. In the new formation, the hastati, principes, and the triarii would
all fight together as one cohesive tactical unit, and any time these classes fought in unison it was
considered to be a cohort. The legions would now consist of ten cohorts of 600 men each, thus,
six centuries to each legion. As well, changes were made regarding the velites and the Roman
cavalry, for now these particular groups would only be recruited from outside the Roman state.
These men would be named auxilla troops, which were, in essence, non-citizen and non-allied
The Roman tactics of actual combat remained consistent with manipular doctrines. The
legions still fought in waves of three and gaps were still maintained for interchange amongst the
troops. And as stated earlier, the classes of hastati, principes, and triarii remained, but remained
so in name only, for now there was no real distinction between these groups. They were all now
armed with the gladius sword and pila, and fought together as a tactical unit.
The cohortal legion lasted from 100 B.C. up through the Roman Imperial era, and it
proved to be a very successful formation for the Roman legions. It was big enough to fight as
separate units if necessary, but was not too large as to become inflexible in difficult terrain. It
was the perfect compromise between the phalanx and the manipular legion.
Due to Marius' reforms, the Roman legion had transformed itself into a well disciplined,
highly efficient, tactically sound professional war machine. But of course, deficiencies were
still manifesting themselves from the reorganization, for because of the new lower classes re-
cruited into the armies, the men became allied to their specific general and not to the Roman
state. The generals were paying their soldiers handsomely in the enemy plunder, and this would
eventually lead into the bloody Roman civil wars in the coming years.
It could be argued that one of the greatest empires in the history of man was the Roman
Empire, and contrary to popular belief, it was not the Roman's political structures, or the
splendid Roman culture, or even their intellect that permitted their longevity, but rather it was
primarily the Roman Army that made this possible. For centuries, the legions expanded their
territories at will, while subjecting the conquered nations to Roman culture, and they success-
fully defended their extensive borders against barbarian invaders for hundreds of years. The
Roman Military has, no doubt, left an indelible mark on the history of warfare, one so prevalent
that in our own nation's military we can see considerable influence.
From their early phalanx legions, to the manipular legions of Camillus, right up to the
cohortal legions, the Roman Military has shown an uncanny ability to adapt as the situation
dictated. When each of their previous formations became obsolete, contrary to what many
nations would have done, the Romans reevaluated and reorganized. If nothing else, the Roman
Army proved to be a pragmatic, forward looking, and strategically efficient fighting unit for
most of their one-thousand year history.