roman legions

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roman legions

Originally the Roman word "legio" meant conscription in reference to a given year’s mobilized forces – we should remember that the early Roman army wasn’t professional but made up of the various census classes of citizen who at the end of the war season would return to their fields and daily lives. Thus there was effectively a new army every year with few bonds between individuals or particular attachment to their unit.

As the population increased and as wealth also increased with it, the number of citizens called to arms consequently grew: the legion no longer represented the entirety of the year’s conscription but the largest unit of military force into which citizens would be assigned on the day of conscription.

Six elected tribunes, in pairs, took two monthly turns to command the legion. A Roman legion included about 4200 legionaries and 300 equites (cavalry) which would, on the battle field, be set out in three rows ("triplex acies") of well armed foot soldiers and a fourth of lightly armed velites. The velites would start the battle with skirmishes and then retreat to form the rear-guard or be spread evenly across the other three row of infantry. I say about 4200 legionaries because according to the severity of the situation and how long the legion had been engaged in war could imply that it was more or less replenished with men, usually of the younger and less experienced classes. At the start of the campaign the legion could carry more than 4200 and by the end have rather fewer.

The first true line was therefore that of the "Hastati", followed by the "Principes" and "Triarii" – heavily armed infantry. The lines were be made of 10 (some suggest 15) rectangular blocks of soldiers known as "manipulus", each block set apart from the next by an open space the size of a manipulus. The manipuli of the three rows were set out as if on a chequers board so that each manipulus had an open area ahead of it.

If each manipulus was approx 18m in width and 12 in depth then we can quickly see that the width of a legion in battle formation was approximately 360m. To this we should add the fact that the velites (relatively untrained old and poor) could be distributed evenly across the armed infantry, therefore increasing their number and space required across the field of battle.

The Manipulus

The manipulus was the smallest tactical unit within the Roman army, the soldiers within it responded to a single banner/standard.

Differently from the Greek compact phalanx formation, the Roman manipulus was able to engage in cohesive action as a single unit as well as personal hand-to-hand combat because the soldiers were set out with a broad space between one and the next, sufficient to allow them to swing and use their weapons in relative individual freedom.

A manipulus contained two "centuriae" which in the case of the Hastati and Principes consisted of 60 legionaries and of the Triarii (veterans) consisted of 30. Ie manipulus of Hastati or Principes = 120 legionaries and a manipulus of Triarii= 60 legionaries.

"Management" of these basic units involved a handful of specific roles. Each century had (remember 2 centuries per manipulus):

Ancient Roman Cavalry

The cavalry was made up of elite citizens and nobility. Frequently including young men keen to make themselves known for their courage. They carried a spear, a sword, a small light round shield and no armour. They rode without stirrups but in a very ergonomic saddle which permitted them stability and mobility whilst on horseback.

Each legion would have its support of approximately 300 cavalry men subdivided into ten units of 30 men. The units in this case were called "turmae" (rather than "manipuli" for infantry). Each ten men had a "Decurion" and an "Optio" (equivalent of the centurions and optios of the manipuls) ie a turma would have 3 decuriones and 3 optios, the highest ranking of these being called a "praefectus".

Allied troops double up the legion’s size

Allied troops provided by the "Soci" – allies of Rome – formed a wing of the legion and matched it in size, often exceeding it, in number of men and cavalry. They were headed by three Roman prefects (nominated by the Roman consuls) who would command allied officers below them.

As opposed to the manipuls, allied troops were sub-divided into "cohorts": 10 cohorts made a support unit of allied troops, likely composed of 400-600 men. It is likely that the cohorts would be subdivided into manipuli similar to those of the Roman legion.

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