Download The Roman Army in the Era of Julius Caesar

Vercingetorix surrenders to Julius Caesar following the Battle of Alesia.
The Roman Army in the
Era of Julius Caesar
by Joseph Miranda
T
he 1st century BC saw the
greatest wars of the Roman
Republic: Julius Caesar’s
conquest of Gaul, civil conflicts among
various contenders for state power, and
the consolidation of the Republic’s vast
territories into what would become
the Empire. The instrument used to
achieved this was the Roman Army.
Up Front with Lucius
Vorenus and Titus Pullo
The Roman army of the 1st
century BC was organized under
what are usually termed the Marian
reforms, which were implemented
circa 100 BC. The improvements
are attributed to Caius Marius, a
Roman consul (one of the two chief
executives of the Republic) and
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general. Marius’ reforms were in part
organizational and part political.
Prior to the Marian reforms, Roman
armies were made up of a general
levy of citizens, who considered it
their duty to serve in the ranks. One’s
position in the legion depended upon
wealth and status, and it was an honor
to be up front. This system broke
down as the Roman Republic found
itself running an empire, having to
fight wars continuously and keeping
troops stationed abroad for many
years. Meanwhile, the demographics
of Rome were changing, with smaller
farmers being dispossessed by
large plantations owned by great
land magnates, and thousands
of unemployed flooding cities.
Marius opened up the army to
recruitment from all classes, bringing
the aforementioned unemployed into
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the ranks. Technically, all legionary
recruits had to be citizens, but during
the later Civil Wars non-citizens
were recruited, often with the
promise of citizenship for service.
In the past, a citizen-soldier might
expect to go home after the end of a
campaign, now legionaries stayed in
the ranks until discharged. The usual
tour of duty was 16 years, though,
in emergencies, recruits might sign
up for shorter terms. With the army
increasingly composed of long-term,
full-time troops, professionalism
increased. Also increased was the
dependency of the troops on their
generals to provide them with a square
deal. Veterans expected a settlement
of land or other rewards—which
could include bounties of cash
and loot. This changed the balance
of domestic power, as armies
The success of Rome can be attributed to the professional strength of its legionaries.
could be used to gain political
advantages in Rome. It also meant
that the state was sliding towards an
increasing numbers of civil wars.
The organization of the legions
also changed. The Roman legions
which fought in the Punic Wars and
against the armies of Alexander
the Great’s successors are called
manipular as they were organized
into 30 maniples. Hastati (spearmen)
were the younger men who formed
the front line; Princeps (“first rankers”,
actually forming the second line) were
veterans; and Triarii (“third rankers”)
were the older men armed with spears
and forming the last line as a final
reserve. There were also Velites, light
infantry armed with javelins, and a
cavalry contingent of 300 horsemen.
The manipular legion was a combined
arms organization. The total strength
was about 5,000 combatants.
Marius simplified this organization,
sweeping away the distinction in
troop types and having only one
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◆
Chronology
All dates are BC.
106-101 Rise of Marius. Caius Marius reorganizes the Roman army.
He defeats King Jugurtha of Numidia in Africa and annihilates
invading Cimbri and Teutones tribes in the north.
91-88 Social War. Rome’s Italian allies rebel. The war
ends with Rome granting citizenship to them.
89-84 First Mithridatic War. Mithridates of Pontus is on the march in Asia Minor,
threatening Roman holdings; meanwhile, his fleet controls the Aegean. Lucius
Cornelius Sulla defeats Mithridates in several battles. Lucius Licinius Lucullus
mobilizes a fleet and regains control of naval lines of communications.
88-72 Various Civil Wars. Marius and Sulla lead respective factions of populists
against the oligarchs. Marius dies in 86, and Sulla is declared dictator two
years later. Sulla instituted conservative reforms and retires in 79. Quintus
Sertorius, one of Marius’ supporters, takes over Spain and defeats several
Senatorial attempts to unseat him; he defies the Senate until assassinated.
83-81 Second Mithridatic War. Brief clashes between
Pontian and Roman forces, ends in a truce.
79-72 Limited anti-pirate campaigns. Romans conduct separate
campaigns against pirate bases in Asia and Cyrene successfully.
Marcus Antonius Creticus is defeated in Crete.
75-65 Third Mithridatic War. Lucullus defeats Mithridates
and invades Armenia in a successful campaign.
73-71 Third Servile War. Spartacus leads a slave rebellion until defeated
by Marcus Licinius Crassus; Pompey mops up the last of the rebels.
67 Pompey versus the Pirates. Pompey defeats the
pirates in a stunning three-month campaign.
65-61 Pompey marches east. Granted supreme powers by the Senate,
Pompey finishes the wars against Pontus and Armenia, then conquers
the remnants of the once mighty Seleucid Kingdom. He reorganizes
the Roman system of provinces and clients in the East.
63-62 Conspiracy of Catiline. Consul Marcus Tullius Cicero defeats
Roman insurrectionists led by Lucius Sergius Catiline.
60 First Triumvirate. Pompey allies himself with Crassus and
Gaius Julius Caesar to share power in Rome.
58-50 Gallic War. Julius Caesar conquers Gaul (modern France and Belgium).
54-53 Carrhae Campaign. Crassus invades Parthia with a Roman army
but is defeated and killed by Parthian horse archer tactics.
49 Caesar crosses the Rubicon. Growing rivalry between Pompey
and Cesar leads to open civil war. Caesar brings his army to Italy,
crossing the Rubicon River. Pompey flees to the East.
49-44 Great Civil War. Caesar is opposed by the Senatorial faction, led by
Pompey. Caesar defeats Senatorials in several battles, including Pharsalus
(48 BC). Pompey flees to Egypt where he is killed by a local faction.
45-44 Caesar at Rome. Caesar consolidates his victories by
setting himself as dictator and implementing reforms at
home. He is assassinated on 15 March 44 BC.
43-30 Civil Wars. Octavian, Caesar’s heir, takes command of his faction along
with Marcus Antonius. They defeat the last of the Senatorial forces. Octavian
and Antonius have a falling out. This leads to a renewed round of civil war,
ending when Octavian invades Egypt and defeats Antonius and Cleopatra.
27 Augustus. Octavian is now ruler of the Roman world. The Senate gives him the
title of Augustus. The Republic has ended, and the Empire officially begun. ◆
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class of infantry. Now all legionaries
were armed in the same manner,
usually with a helmet, chain mail
armor, an oval shield, a short sword
(the famous gladius) and several of
the heavy javelins called pila. He also
combined the maniples into 10 cohorts
per legion. The reason for this is that
the older organization contained
too many troop types, and while this
worked against the more precise
armies of Carthage and the Hellenistic
kingdoms, it lacked the flexibility to
deal with the broad range of foes that
Rome now faced. This was especially
so now that Rome was coming into
contact with barbarian peoples such
as the Gauls and Germans, where an
unbroken line of cohorts were needed
to face their often ferocious charge.
The cohort organization simplified
training since there was only one type
of heavy infantryman in the legion.
The legion commander was called
a legate (lieutenant, in the sense
of being an officer with delegated
authority), assisted by several tribunes
who functioned as staff officers. Also
present were aides called the comites
praetori (headquarters companions).
There were also specialists, including
a praefectus castrorum (camp prefect)
who was a senior man responsible
for setting up fortified camps and
logistics, as well as engineers,
physicians, and paymasters. Each
legion has its aquila “eagle" standard.
Carrying the aquila was considered
to be a great honor and losing the
legion’s eagle was what today would
be called a “career ending move.”
A legion’s first cohort (and
presumably most experienced)
had 800 men, organized into five
centuries. The other nine had 480
each, organized into six centuries.
Each century was commanded by a
centurion, assisted by an optio and
a signifier (standard bearer). There
is a debate about whether or not
centurions also commanded cohorts,
or if they were under direct control
of the legion command staff. The
most senior of the centurions was
called the primus pilus (“first ranker”,
not “first spear” as it is sometimes
Gaius Marius, who transformed the Roman legions into a force capable of controlling an empire.
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translated, though this interpretation
does have an appeal to those who
give slang names to military ranks).
Total strength was about 5,200 men,
including various additional officers
and specialists, though in the field,
between 2,000 and 4,000 legionaries
might actually be in the ranks owing
to casualties, furloughs, detached
duties and general attrition.
Generals organized a cohors
praetorian (headquarters cohort)
as a sort of elite force and final
reserve. In later centuries, the
Praetorian Guard would become
the imperial guard and a power
broker, but during the Republic the
praetorians served at the army level.
The legionaries were highly trained
and subject to intense discipline. This
paid off during battle, and during
prolonged campaigns in keeping
the troops together. Command was
improved during the 1st century BC
as officers had the advantage of more
practical experience in the field. There
was considerable attention to logistics
and each legion had a baggage train
(impedimenta). Supply trains were
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cut down to maximize movement,
and individuals carried much of their
equipment, though pack animals and
wagons were used. The central supply
issue was the provision of food, which
would come from centralized depots,
or be foraged—the latter preferably
when fighting in the enemy’s territory.
Legionaries performed engineering
duties, such as building fortified
camps and roads. Military engineering
skills were highly developed, with the
legions constructing bridges rapidly
to cross rivers and impress upon the
locals the mobility of Roman armies.
Tactics were flexible, facilitated
by the joint organization for all
cohorts. Each legion would be
arrayed in a line of one, two or three
cohorts. Sometimes a fourth line
was used in the form of a general
reserve, such as Julius Caesar’s
deployment at Pharsalus (48 BC).
Standard deployment was in a
checkerboard pattern of cohorts.
This increased maneuverability as
individual units could turn to fight
in various directions. It also meant
that if one cohort were shattered
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javelins—though Marcus Licinius
Crassus would find out differently
when he went up against the Parthians
in 53 BC. Some Legionaries might
be pulled out of the ranks to act as
light infantry, discarding their heavier
armor and using pila and slings
instead. Legions also had contingents
operating light missile engines,
which were sometimes brought onto
the battlefield and were inevitably
found in Roman fortified camps.
Light troops were provided
by the allies and by mercenaries.
These included archers, slingers,
and light spearmen. These were
used to skirmish, fight in broken
terrain, screen the deployment of the
heavier formations, and to protect
the flanks. Little is known today of
the organization of light troops. The
practice of the later Empire was to
organize them in various types of
cohorts though it is entirely possible
that during the late Republic they
retained their native organization.
A legion had a contingent of 300 or
so citizen cavalry, organized into ten or
twelve turmae. These were frequently
absent. Cavalry in this period was
provided by allies and mercenaries.
They were usually massed in separate
formations outside of the legion
structure. Caesar made considerable
use of Gallic and Germanic cavalry.
They seemed to have remained loyal
even when fighting their countrymen,
though it should be remembered that
at the time, Gaul and Germany were
divided into numerous rival tribes,
divisions the Romans frequently
exploited for their purposes.
Cavalrymen were mainly of the
light type, armed with a spear, sword,
and some chain mail armor. They
were used to screen and pursue, but
there are several recorded incidents
of Roman horsemen breaking enemy
lines with a hard charge. Cavalry
frequently used fire tactics by riding
up to an enemy line and throwing
showers of javelins to disrupt it.
Auxiliaries also included heavier
troops. Roman armies operating in
the former Hellenistic kingdoms had
access to hoplite style heavy spearmen,
and heavy cavalry. Contemporary
historians claim that Roman armies
in the 1st century BC campaigns
against Pontus and Armenia often
took on incredibly larger armies
and defeated them handily. It needs
to be borne in mind that Roman
or panicked, it would not carry
away the rest of the line in a rout.
There is debate as to whether the
succeeding lines of cohorts moved
forward to fill in the inter-unit gaps
once the legion had clashed with the
enemy. The gaps may have been left
open, and when the enemy moved
into them, he was attacked on his
flanks with pila. Given the flexibility
of the legion, any number of open and
close formations were employed.
There were also a couple of
specialized formations. The orbis
(circle) was an all-around defense.
The testudo (tortoise) had legionaries
closing up and interlocking
shields to enhance defense.
Allies and Auxiliaries
The Legion of the 1st century BC
had no organic light infantry though
the armament of pila gave the troops
a missile capability. Most archers in
the Mediterranean and surrounding
lands in this period were armed with
relatively weak bows, and might be
countered by showers of pila and
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