Auxiliaries are support personnel that assist the military or police but are organised differently from regular forces. Auxiliary may be military volunteers undertaking support functions or performing certain duties such as garrison troops, usually on a part-time basis. Unlike a military reserve force, an auxiliary force does not necessarily have the same degree of training or ranking structure as regular soldiers, and it may or may not be integrated into a fighting force. Some auxiliaries, however, are militias composed of former active duty military personnel and actually have better training and combat experience than their regular counterparts. Historically, the designation auxiliary has also been given to foreign or allied troops in the service of a nation at war, most famously the eponymous Auxilia serving the Roman Empire. In the context of colonial troops, locally recruited irregulars were often described as auxiliaries. Historical usage Roman 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. United Kingdom and the British Empire At the start of the 18th century, the English (from 1707, British) military (as distinct from naval) consisted of several regular and reserve military forces. The regular forces included district garrison artillery establishments that maintained forts and batteries, as well as field artillery, ready for war, with the batteries brought up to strength in war time by drafts from other military or naval forces, and field artillery trains formed during wartime,