Auxiliary force

An auxiliary force is an organized group supplementing but not directly incorporated in a regular military or police entity. It may comprise either civilian volunteers undertaking support functions or additional personnel directly performing military or police duties, usually on a part-time basis.

Historically the designation "auxiliary" has also been given to foreign or allied troops in the service of a nation at war. In the context of colonial armies locally recruited irregulars were often described as auxiliaries.

Auxiliaries in the Roman army were recruited from provincial tribal groups who did not have Roman citizenship. As the Roman army of the Republican and early Empire periods was essentially based on the heavy infantry who made up the legions, it favored the recruitment of auxiliaries that excelled in supplementary roles. These included specialists such as missile troops (e.g. Balearic slingers and Cretan archers), cavalry (recruited among peoples such as the Numidians, and the Thracians), or light infantry. Auxiliaries were not paid at the same rate as legionaries, but could earn Roman citizenship after a fixed term of service.

By the 2nd Century AD the auxiliaries had been organised into permanent units, broadly grouped as Ala (cavalry), Cohors (infantry) and Cohors equitata (infantry with a cavalry element). Both cavalry alae and infantry cohors numbered between 480 and 600 men each. The mixed cohors equitata usually consisted of 6 centuries of foot soldiers and six squadrons of horsemen. Specialist units of slingers, scouts, archers and camel mounted detachments continued in existence as separate units with a regional recruitment basis.

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