Tactics in Battle


Command and Control

Tactical command of the legions was achieved through horns, standards, couriers and verbal messages passed through the ranks. Unfortunately, we don't know the exact system of signalling used.

We do know that four different types of horns were used for tactical control: the tuba, the bucina, the cornu, and the lituus. (See the Musical Instruments page for more details.) We also know that operational orders from the commander were always prefixed by the sounding of the cornu, followed by the relevant signal on the tuba, then followed by the appropriate movement by the standards.

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The tactical fighting unit of the Late Republican era was the cohors (the cohort). The cohort contained three manipuli (maniples, companies) consisting of two centuries, one behind the other, each maniple standing side by side. Each cohort had four or five ranks (lines) depending upon the number of legionaries in them.

We don't know the intervals between cohorts in Caesar's time. However, some authorities estimate that:

  • The close order interval was almost a meter (3 feet), with the interval between cohorts being 1 cohort width
  • The battle Order (aka open order) interval was 1.8 meters (6 feet), with the interval between cohorts still 1 cohort width

In battle, the first two lines were deployed in open

Triplex Acies Diagram

Duplex Acies Diagram

order and the third (at the rear) was held in close order.

On the battlefield, cohorts could be organized into

  • the triplex acies--three lines consisting of 4 cohorts in the first, 3 cohorts in the second, and 3 cohorts in the third. The distance between cohorts. The three lines were some 150 feet- 200 feet apart, although that's still debated by historians.[Click on the diagram to see an enlarged version of the triplex acies.]
  • the duplex acies-- two lines consisting of 5 cohorts in one line and the remaining 5 cohorts in the second. [Click on the Duplex Acies diagram to see an enlarged version of it.]
  • the simplex acies--one line of 10 cohorts
  • the testudo (turtle) was used when advancing or retreating under heavy fire. The front ranks held their scuti in front of them while the internal ranks held theirs over their heads.


On the march, cohorts could be organized into:

  • the agmen quadratum (the hollow square): four columns of troops mraching in parallel. Used when in hostile territory since it was easy to shift into a triplex acies at the first sign of trouble.
  • the orbis (the circle) was used if the legion had to retreat under fire

Auxiliaries fought in front and on the flanks of the legionaries. Cavalry were deployed on the flanks. Some historians/archaeologists conjecture that the cavalry rode in 4 lines of 8; but there's no conclusive evidence as to what their formation really looked like.

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Legionary Fighting Tactics

The typical Sequence of Events during a battle:

  • Troops assembled and the commanding general addressed them in order to fire them up for the ensuing battle.
  • Up and down the line, horns sounded, signalling the general's orders
  • The skirmishers and auxilaries moved forward, with the slingers and archers giving them covering fire.
  • The legions would wait for the enemy to advance. If he didn't, they'd advance. If he did, they'd wait. When the legionaires were within about 250 paces of the enemy, they would run at the enemy. Ten to twenty paces from the enemy line, the first two ranks would hurl their pila at the enemy. If gaps in the line were produced, they'd set to with gladii. If no gaps were produced, the remaining ranks would launch their pila.
  • The legions gave their battle cry and advanced in the appropriate formation (usually the triplex acies). In the first line marched the antesignani, followed by the standards, then the princeps; and, lastly, the most experienced troops, the triarii. The cavalry rode on the flanks of the formation to protect them.
  • The antesignani engaged the enemy first by hurling their pila and then drawing swords and clashing with the enemy line.. When they tired, ceased to gain the advantage, or were pushed back, the hastati moved in. If the hastati ran into similar problems, the triarii engaged the enemy. (In Caesar's armies, the order of battle was reversed.).
  • If a victory were won, the cavalry would pursue the enemy. If the day were lost, the legion would retire to the camp using their reserves or the least exhausted troops and the cavalry to cover their retreat.

Since unbroken cohorts couldn't be attacked effectively except along their flanks, cavalry were used most of the time to attack enemy cavalry rather than infantry. If the cavalry couldn't be used for some reason, it was held in reserve to the rear of the formation.

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Close Combat Tactics

The Romans stabbed rather than sliced with their gladii. Favorite targets were the face, the belly and the legs. Here's an excerpt from Caesar's Legions by Sekunda, Northwood, & Simkus (see the Ancient Rome page for a more bibliographic info) which describes Roman fighting tactics:

    "The Romans used their swords to stab, keeping the hilt low and thrusting at the face, abdominal cavity and legs of an opponent. The thorax was avoided . . . Cutting strokes were avoided as much as possible . . . The Romans were said to have despised enemies, who laid about themselves with long slashing blades, and despatched them with ease . . . The recruits would be taught to use the legionary shield as a weapon as much as a defence. . . . The boss of the shield was certainly used to punch opponents and the edge may also have been used to strike an enemy in the face; the latter method is shown in early gladiatorial sculpture, but might have required more strength to achieve than was possessed by the average soldier."

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Auxiliary Fighting Tactics

Bowmen (sagittarii) and slingers (funditores) were skirmishers having no regularly assigned tactical position. Slingers were normally stationed, intermingled with the archers, on the flanks to protect the legionaries from cavalry attack. However, they were sometimes used as light infantry in front of the legionaries or to provide covering fire for infantry during a siege.

Fustibalatores (sling-staffers) would have acted with the archers to engage the enemy at long range and attempt to break their forward momentum. Conventional funditores (slingers) might sometimes be used this way; but, most of the time, they were employed to protect the flanks of a formation or to provide covering fire during an advance.

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Other Facts

  • The chief standard of the Legion was its aquila-- an Eagle atop a thick, spiked golden staff, which was carried by an aquilifier (Eagle-bearer). The eagle gripped a golden thunderbolt in its talons, its wings were lifted and head tilted forward as if it were ready to take off.
  • To lose or surrender an aquila or any other standard was a shameful disgrace. On the march, the army's standards were carried at the head of the legions. In the camp, they were planted in the ground inside of special shrines of their own, while watch was kept over them
  • An army of seven legions in three lines--roughly 25,000 men--would represent a front of a mile and half.
  • The legionary bore his scutum on his left arm and used his gladius with his right.
  • The light infantry was charged with replenishing the fighting line's supply of javelins by collecting javelins hurled at the army's forces.
  • The military language of the time reflects how the Romans used the standards to signal movements in battle. Here's a few examples:
    • signa inferre = to attack
    • signa referre = to retreat
    • signa convertere = to turn about
    • conversa signa inferre = to turn around and attack
  • Before going into battle, the auspices were taken. A sacrifice of sheep, ox, and/or pig would be made; and a priest would examine its entrails to see if the signs were favorable for victory.
  • A purple tunic was hung in front of the commander's tent to signify that battle was about to be given.

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Sunday, January 20, 2008