When Cyprus was incorporated into the Imperium Romanum in 30 BC, the island became a potential recruiting-ground for the Roman army, and military service a potential career for male Cypriots. Two classes of fighting men made up the Roman army. The legions were composed of citizen soldiers and recruited among holders of the Roman franchise, while the auxilia were recruited from non-citizens but received Roman citizenship when they were discharged after twenty-five years' service. To date, no legionaries of Cypriot background have been found in the literary or epigraphical record, but an auxiliary cohort of Cypriots saw service in Romania and the Black Sea region.
After the battle of Actium and the military reforms of Augustus, auxilia came to play a significant role in the Roman army, especially in the north-west border provinces. Previously, auxiliary units had been of varying size; now they were divided into cavalry alae and infantry cohortes of c. 500 men, each cohort subdivided into 6 eighty-man centuriae. Under Augustus, auxiliaries generally served in the area where they had been recruited, often as ethnic units under their own commanders. This policy was gradually abandoned and completely reversed after a series of mutinies and separatist uprisings that shook the Rhine frontier in AD 68-69: cohorts were henceforth stationed outside their area of origin and vacancies filled by local recruitment. By the second century, the auxiliary units had lost much of their ethnic character, but retained their traditional appellations.
Until the mid-first century AD, Roman policy in the Black Sea was based on indirect control of the shores through client-kings. In 61, Scythian forces were besieging Chersonesos (Sevastopol) in the western Crimea, but Kotys, ruler of theBosporanKingdom in the eastern Crimea, was unable or unwilling to come to the aid of Chersonesos, and his Roman masters had to intervene directly. An expeditionary force under the command of Ti. Plautius Silvanus, legate of Moesia, forced the Scythians to abandon the siege. Subsequently, Roman control of the BosporanKingdom was tightened, and the kingdom of Pontos was made a Roman province. When the expeditionary force returned to its bases in Moesia, a sizeable contingent?according to Josephus, 3,000 men and 40 ships?stayed behind to safeguard Roman interests. Guard duty on the frontier was a typical task for auxiliary units, and it may well be in this context that a unit of Cypriot auxiliaries was raised: Greek-speaking and familiar with the sea, Cypriots were well suited for garrison duty in the northern Black Sea ports.
A generation later, around AD 85, Moesia itself was attacked by Decebalus. Rome was forced to divert forces from the Black Sea coast to the central Balkans. The participation of a Cyprian cohort in the Dacian wars has long been known from a military diploma dated February 110, recording the granting of Roman citizenship and other privileges to veterans of the Dacian wars. A similar diploma, dated to October 109 and found at Ranovac in north-eastern Serbia, was published in 1987.Both diplomas list a number of units, veterans of which benefit from the emperor's decree, and in each list, the cohors IIII Cypria c(ivium) R(omanorum) appears