Ala

An ala (Latin ala, “wing”) was an independent cavalry regiment of the auxilia in the army of the Principate, normally commanded by a prefect. It differed both from cavalry attached to a legion and from the mounted element of a mixed auxiliary cohort. The term was older: in the Republic, the allied “wings” contained infantry as well as cavalry. An ala sociorum and an imperial cavalry ala were therefore not one unchanging organisation.

The ala was divided into turmae commanded by decurions. In On the Layout of Military Camps, section 16, Pseudo-Hyginus distinguishes sixteen turmae in an ala quingenaria and twenty-four in an ala milliaria. These names denote nominal strength classes, not verified rolls of exactly 500 and 1,000 riders. A common reconstruction using thirty-two men per turma gives approximately 512 and 768 personnel respectively. The number of horses should not simply be equated with the number of soldiers, since remounts were also needed.

Alae were not identical across every region and century. A unit name could retain its founder’s name, recruiting people or honorary title long after its composition changed. Cavalry undertook reconnaissance, escorted the army, covered its flanks and pursued opponents. Equipment and fighting methods varied with period and specialisation.

A soldier of an ala was called an alaris. Camel units and late Roman formations called alae require separate consideration: similar terminology does not prove that they all followed the cavalry organisation of the first and second centuries CE.

Related topics

Roman cavalry, Legion, Auxilia, Cohort

Literature and sources

Ala,in the Roman army // Encyclopedic dictionary of Brockhaus and Efron: in 86 vols. (82 vols. and 4 supplements). - St. Petersburg,1890. - Vol. I. - p. 344. - Pseudo-Hyginus. On the Layout of Military Camps, 16: turmae and accommodation of alae. Latin text