Auxiliary infantry. 8 figures, 4 variants in lorica hamata (chaimail) and holding a spear
The Auxilia (Latin, lit. “auxiliaries”) constituted the standing non-citizen corps of the Imperial Roman army during the Principate era (30 BC–284 AD), alongside the citizen legions. By the 2nd century, the Auxilia contained the same number of infantry as the legions and in addition provided almost all of the Roman army’s cavalry and more specialised troops (especially light cavalry and archers). The auxilia thus represented three-fifths of Rome’s regular land forces at that time. Like their legionary counterparts, auxiliary recruits were mostly volunteers, not conscripts.
The Auxilia were mainly recruited from the peregrini, free provincial subjects who did not hold Roman citizenship and constituted the vast majority of the population in the 1st and 2nd centuries (c. 90% in the early 1st century). In contrast to the legions, which only admitted Roman citizens, members of the Auxilia could be recruited from territories outside of Roman control.
Auxiliary regiments were often stationed in provinces other than that in which they were originally raised, for reasons of security and to foster the process of Romanisation in the provinces. The regimental names of many auxiliary units persisted into the 4th century, but by then the units in question were different in size, structure, and quality from their predecessors.
These all-infantry units were modelled on the cohorts of the legions, with the same officers and sub-units. They were typically considered to be more of a light infantry than proper legionaries. Some auxiliaries may however have been equipped with the lorica segmentata, the most sophisticated legionary body-armour, although scholars dispute this.
There is no evidence that auxiliary infantry fought in a looser order than legionaries. It appears that in a set-piece battle-line, auxiliary infantry would normally be stationed on the flanks, with legionary infantry holding the centre e.g. as in the Battle of Watling Street (AD 60), the final defeat of the rebel Britons under queen Boudicca. This was a tradition inherited from the Republic, when the precursors of auxiliary cohortes, the Latin alae, occupied the same position in the line. The flanks of the line required equal, if not greater, skill to hold as the centre.