Editing Roman legion (section)

=== Mid Republic (509–107 BC) ===
{{Main|Roman army of the mid-Republic}}
At some point after the [[overthrow of the Roman monarchy]] the ''legio'' was subdivided into two separate legions, each one ascribed to one of the two [[Roman consul|consuls]]. In the first years of the Republic, when warfare was mostly concentrated on raiding, it is uncertain if the full manpower of the legions was summoned at any one time. In 494 BC, when three foreign threats emerged, the dictator [[Manius Valerius Maximus]] raised ten legions which [[Livy]] says was a greater number than had been raised previously at any one time.<ref>[[Livy]], ''[[Ab urbe condita (book)|Ab urbe condita]]'', 2.30</ref>

Also, some warfare was still conducted by Roman forces outside the legionary structure, the most famous example being the campaign in 479 BC by the clan army of gens Fabia against the Etruscan city of Veii (in which the clan was annihilated). Legions became more formally organised in the 4th century BC, as Roman warfare evolved to more frequent and planned operations, and the consular army was raised to two legions each.

In the Republic, legions had an ephemeral existence. Except for Legio I to IV, which were the consular armies (two per consul), other units were levied by campaign. Rome's Italian allies were required to provide approximately ten cohorts (auxilia were not organised into legions) to support each Roman Legion.

In the middle of the Republic, legions were composed of the following units:
* ''[[Equites]]'' (cavalry): the [[cavalry]] was originally the most prestigious unit, where wealthy young Roman men displayed their skill and prowess, laying the foundation for an eventual political career. Cavalry equipment was purchased by each of the cavalrymen and consisted of a round shield, helmet, body armour, sword and one or more lances. The cavalry was outnumbered in the legion. In a total of {{circa|3,000}} men (plus the ''velites'' that normally enlarged the number to about 4,200), the legion only had around 300 horsemen, divided into ten units (''[[turma]]e'') of 30 men. These men were commanded by [[Decurion (Roman cavalry officer)|decurions]]. In addition to heavy cavalry, there would be the light cavalry levied from poor citizens and wealthy young citizens not old enough to be in the ''hastati'' or the ''equites''. In battle, they were used to disrupt and [[flanking maneuver|outflank]] enemy infantry formations and to fight off enemy cavalry. In the latter type of engagement, they would often (though not always) dismount some or all of the horsemen to fight a stationary battle on foot, an unusual tactic for the time, but one that offered significant advantages in stability and agility in a time before [[stirrup]]s.<ref>Mccall, Jeremiah B. ''The Cavalry of the Roman Republic: Cavalry Combat and Elite Reputations in the Middle and Late Republic.'' (New York, Routledge, 2002) pp. 53ff</ref>
* ''[[Velites]]'' ([[light infantry]]): these were mainly poorer citizens who could not afford to equip themselves properly. Their primary function was to act as [[Skirmisher|skirmishers]] – javelin-throwers, who would engage the enemy early in order either to harass them or to cover the movement of troops behind them. After throwing their javelins, they would retreat through the gaps between the maniples, screened from the attack of the enemy by the heavy infantry lines. With the shortage of cavalry in the army of the early to mid Republican army, the ''[[velites]]'' were also used as scouts. They did not have a precise formal organisation or formation.
* [[Heavy infantry]]: this was the principal unit of the legion. The heavy infantry was composed of citizen legionaries that could afford the equipment composed of a bronze helmet, shield, sword, armour and ''[[pilum]]'', a heavy javelin whose range was about 30 metres. After the Second Punic War, the preferred weapon for the hastati and ''[[principes]]'' was the ''[[gladius]]'', a short sword.<ref>{{Cite journal|last=Quesada Sanz|first=Fernando|date=28 September 1996|title=Gladius hispaniensis: an archaeological view from Iberia|url=https://www.uam.es/FyL/documento/1446794703147/Quesada-gladius-ROMEC-rd.pdf|journal=Journal of Roman Military Equipment Studies|volume=8|pages=251–254}}</ref> Their hobnailed sandals (''[[caligae]]'') were also an effective weapon against a fallen enemy. Heavy infantry was subdivided, according to experience, into three separate lines of troops:
** The ''[[hastati]]'' ({{singular}}: ''hastatus''): these consisted of raw or inexperienced soldiers, considered to be less reliable than legionaries of several years' service. The Hastati were placed at the front for several reasons. One reason is the city of Rome could ill-afford to lose experienced soldiers, so they put the greenest soldiers at the front. If they survived, the ''hastati'' would gain invaluable experience. Another reason is if the newest soldiers succumbed to battle nerves and broke and tried to run, then there were experienced soldiers behind them to stiffen their resolve.
** The ''[[principes]]'' ({{singular}}: ''princeps''): these were the more experienced soldiers, often better equipped than the ''hastati'', and having more experience on the battlefield, they would take up the second line in the battle in the event the Hastati failed or fled. They were the second wave in an early Republican Legion.
** The ''[[triarii]]'' ({{singular}}: ''triarius''): these were the veteran soldiers, to be used in battle only in extreme situations; they rested one knee down when not engaged in combat. The ''triarii'' served primarily as reserves or [[barrier troops]] designed to backstop the ''hastati'' and ''principes'', and were equipped with long ''[[Hasta (spear)|hastae]]'' (spears) rather than the ''pilum'' and ''gladius'' (the ''hastati'' and ''principes'' stopped using spears in 387 BC). Thus armed, they fought in a [[phalanx]] formation. The sight of an advancing armored formation of ''triarii'' legionaries frequently discouraged exultant enemies in pursuit of retreating ''hastati'' and ''principes'' troops. ''Ad triarios redisse'' – ''To fall back upon the triarii'' – was a Roman [[idiom]] meaning to use one's last resort.

Each of these three lines was subdivided into (usually ten) chief tactical units called [[Maniple (military unit)|maniples]]. A maniple consisted of two [[Centuria|centuries]] and was commanded by the senior of the two [[centurion]]s. At this time, each century of ''hastati'' and ''principes'' consisted of 60 men; a century of ''triarii'' was 30 men. These 3,000 men (twenty maniples of 120 men, and ten maniples of 60 men), together with about 1,200 velites and 300 cavalry gave the mid Republican ("manipular") legion a nominal strength of about 4,500 men.