The most famous units in the Roman army were the legions or divisions stationed in the frontier provinces. They were supplemented by a (numerically equal) force of auxiliaries. In the city of Rome itself, there were several forces, especially the elite praetorian guard that protected the emperor.
The army carried out many duties in addition to those purely military; besides policing, there were bureaucratic functions (cf. the requisitioning in Matt. 5.41; 27.32; for temptation to corruption, see Luke 3.14). Officers, often assisted by small detachments of troops, performed many administrative and judicial tasks.
A legion was commanded by a senator called an imperial legate; under him were six military tribunes and sixty centurions. The full complement of a legion consisted of 5,500 to 6,000 men, who were Roman citizens. There were between twenty‐five and thirty legions, but none was stationed in Judea until the Tenth Legion was sent there in 70 CE after the First Jewish Revolt. But there were four in Syria to the north, deployed in Judea when large‐scale military intervention became necessary.
Legionaries were heavy infantry and were assisted by auxiliaries, especially cavalry, light‐armed troops, and archers; it is not clear which of the latter the dexiolaboi of Acts 23.23 were. Auxiliaries were not Roman citizens, but it became customary to give them Roman citizenship after twenty‐five years of service. The auxilia, as they were collectively known, were grouped into regiments of five hundred (in a few special cases a thousand) strong, called alae if cavalry, cohortes if infantry. Their commanders were prefects (tribunes in the case of regiments a thousand strong), usually drawn from the second order of the Roman nobility. Subordinate officers were called decurions in the alae, centurions in the cohorts.
The Romans also made use of the armed forces of semi‐independent local kings (called “client” kings) within the Roman ambit, such as the Herods. Soldiers from such armies are mentioned in Matthew 2.16 and Mark 6.17. Client kings often organized their armies on the Roman pattern.
The Roman forces mentioned in the New Testament were all auxiliaries. As Jews were excused from conscription into the Roman army for religious reasons, the soldiers at the crucifixion and in Acts were probably Syrian, Samaritan, or Caesarean (from the non‐Jewish population in Caesarea, the administrative capital of Judea): certainly, Herod the Great had Samaritans and Caesareans in his army, who were later incorporated into the Roman forces. Two regiments are named in the New Testament, the Italian and the Augustan Cohort (Acts 10.1; 27.1). These can be compared or equated with the Cohors II Italica Civium Romanorum and the Cohors Augusta I of the eastern command at the time. Both were of higher status than other auxiliary regiments (like those of Syrians or Thracians) and were stationed in Judea, possibly because no legion was there. Claudius Lysias (Acts 21.31; 23.26) is called a chiliarch or tribune, implying that his cohort was a thousand strong (and part of it mounted, if the cavalry escorting Paul came from it).
Denis Bain Saddington