Roman Army: Late Republic

In this blog, we'll dive into the Roman legions from the late republican period. We're focusing on the period from the 2nd Punic War in the 3rd century BCE through the assassination of Julius Caesar.

In our previous blog (Roman legion: Early Republic (500-217 BCE)) we ended after the First Punic War. The Roman army was weakened, but Roman rule over central and southern Italy was a fact. Additionally, Carthage was forced to pay Rome massive compensation to maintain peace.

The Roman Manipular Legion (315–107 BCE)

From the (late) fourth century BCE onwards, the Romans replaced the phalanx formation with a series of small tactical units, the manipuli (maniples), arranged in three lines (triplex acies); the Hastati, Principes, and Triarii. These lines were organized based on wealth class, but also combat experience. The front line consisted of the least experienced (and poorest) soldiers, while the back line was made up of heavily armed veterans. This way, the Roman army kept its strongest troops out of the fight until the end of a battle, allowing them to easily overwhelm an exhausted enemy.

The lines were divided according to a checkerboard pattern (quincunx). The maniples were essentially the old centuriae, but were reconfigured: the units in the first two lines of the triplex acies were enlarged to 120 men, while those in the back line were reduced to 60 men.

The quincunx formation offered much more flexibility and maneuverability than the large, dense mass of a phalanx. The Romans presumably copied this formation from their opponents, the Samnites.

Composition of the Legion

During this period, a Roman legion consisted of approximately 5,000 men. Unlike later legions, which were composed exclusively of heavy infantry, these early legions consisted of a combination of light and heavy infantry. To distinguish them from the later legions of the Empire, which were organized into cohorts, the term manipular legion is used for these early formations.

The manipular legion was organized based on social class, age, and military experience. In practice, this system was sometimes stretched: for example, slaves were forced into service when there was a shortage of soldiers. Normally, one legion was raised each year, but in 366 BCE, two legions were formed in a single year for the first time.

Polybius states that only soldiers worth more than 10,000 drachmas (possibly 40,000 asses) wore a lorica hamata, while the rest wore a pectoral, or a small, square breastplate designed to protect the heart. The First Class primarily served in the cavalry at that time, which would imply that only a small minority of heavy infantrymen wore chainmail. This would also result in different types of shields within the same ranks.

The Heavy Infantry

The foundation of the manipular legion was the maniple, a unit of 120 men consisting of soldiers of the same infantry class. Thanks to their relatively small size, maniples could make flexible tactical movements within the larger army, which was an important improvement over the cumbersome phalanx formation.

During battles, the maniples were usually arranged in three lines, based on the three heavy infantry types: the hastati, principes, and triarii. This system made it possible to effectively utilize the different experience levels and skills of the soldiers. A manipular legion normally consisted of 1,200 hastati, 1,200 principes, and 600 triarii. The three class units still had a parallel with the social divisions within Roman society, but officially, the three lines were based on age and experience, rather than wealth class. Young, inexperienced men served as hastati, older men with some military experience as principes, and veterans of advanced age and experience as triarii.

Hastati

The first type, the hastati, usually formed the first line in the battle order. They wore a Celtic-type Montefortino helmet and usually no body armor, but sometimes had a simple bronze breastplate (cardiophylax). They also sometimes wore greaves, only on the left leg because it protruded from under the shield.

They were armed with a Celtic sword (La Tène type B), a Samnite/Celtic oval shield (the early scutum), and two throwing spears (pilum), of which one was possibly heavier than the other and therefore suitable for use as a thrusting spear.

Principes

The second type, the principes, were wealthier and more experienced than the hastati; therefore they had less need to gain personal glory. These soldiers wore a Celtic chainmail (lorica hamata) and a Celtic-type Montefortino helmet. Like the hastati, they sometimes wore greaves, usually only on the left leg because it protruded from under the shield. They used the same weapons as the hastati.

Some historians believe that until 250 BCE, both the hastati and principes were armed with the hasta (thrusting spear) instead of the pilum (throwing spear), and that this was replaced during the First Punic War, possibly because, like the gladius, it was adopted from the Iberians. But this remains speculative.

Triarii

The third type were the Triarii, the wealthiest and most experienced infantrymen. They fought in the old style in a phalanx formation. They wore greaves, a lorica hamata, and a Montefortino helmet. They were armed with a thrusting spear (hasta) as their primary weapon and fought with oval scutum in a shield wall. They also had, like the Hastati and Principes, a Celtic sword (La Tène type B) as a secondary weapon.

Light Infantry

The light infantry of 1,200 velites consisted of lightly armed scout troops from lower social classes or young men who had yet to make a name for themselves. They were ideal for quick ambushes or plundering enemy territory. On the battlefield, they played an important, undervalued role. They bombarded and shot the enemy with short throwing spears and lead sling bullets that had an impact comparable to a modern pistol.

These groups are particularly interesting because they are an echo of Proto-Indo-European war bands, the koryos.

Velites

The Velites wore no body armor and possibly only sporadically a helmet. They are known for wearing a wolf skin, which points to the Proto-Indo-European koryos tradition. They were armed with short swords (daggers) and carried a short round shield (the Parma). Speed and maneuverability were their primary skills.

Accensi

Accensi (also adscripticii and later supernumerarii) were soldiers who followed the army without specific military duties. They were lightly armed and were placed behind the triarii. Their main task was to fill empty spaces in the maniples, but they also occasionally seemed to have worked as orderlies for the officers.

Rorarii

Rorarii possibly fought in the last line as a reserve unit. They were armed in the same way as the Velites and later probably gave rise to them. They possibly fought simultaneously with the triarii as the last to engage in battle and thereby disrupted the enemy line, while the triarii could execute their phalanx technique. Another possibility is that they were light scouts, similar to the velites, as mentioned by Livius in Book VIII.8. Unfortunately, the evidence is so limited that it's difficult to understand exactly what role the rorarii played.

They could also have been the light equivalent of the triarii, just as the accensi could have been the light equivalent of the principes, with both rorarii and accensi reinforcing the triarii. However, this could also point to different names for the same type of warrior.

Leves

The Leves were light infantrymen who were also armed with throwing spears and had a role similar to the velites and the rorarii. In a legion, there were 300 leves, who, unlike other infantry classes, did not form separate units but were added to hastati units. Their primary task on the battlefield was to harass the enemy with throwing spears, protected by heavy infantry.

The Roman leves from 403 BCE were the first to campaign for longer than a single season, and from this point on, this practice became gradually more common.

Cavalry (equites)

Equites, or cavalry, typically totaled 300 riders per legion. The cavalry was mainly recruited from the wealthiest class of society, but sometimes additional cavalry was also recruited from the Socii and Latini, allies of the Italian mainland.

The equites were a special class within the system. They served in the cavalry. Some received their horses and equipment supplied by the state, while most were wealthy enough to provide these themselves. Although the equites played an important military role, they were subordinate to the infantry in voting rights.

Share