The Roman Army: Key Concepts

 by G. J. Goldberg

        "How many men in a legion?"

        "What is a cohort?"

        "What does a centurion do?"

        These  questions are answered in this overview of the structure of the Roman Army at the time of the Judaean-Roman War of 66-70 CE.

                                       Reference: Peter Connolly, Greece and Rome at War (Greenhill Books, London, 1998)

   At the time of the Judaean revolt, the Roman Army consisted of 28 legions spread across the Empire, together with auxiliary units. Each legion was composed of about 5,500 men, all professional soldiers who signed on for terms lasting 25 years. Only Roman citizens could serve, but citizenship was granted upon enrollment.

   Each legion had a number and a name; both were necessary, as the numbering was not unique. At the time of the Jewish revolt there were two legions each numbered 1,4,5,6,10,15, and 22, and three with the number 3; this situation had arisen from the Roman civil wars when opposing sides had each created and numbered their own legions. The Twelfth Legion, Fulminata, stationed near Antioch in Syria, was nearly destroyed in the initial battle of the Judaean revolt. The Tenth Legion Fretensis occupied Judaea after the war.

   Each legion was divided up into ten cohorts, not of equal size: the first cohort was the largest and contained about 800 men, the others about 500 men each. In addition each legion had 120 horsemen who acted as scouts and dispatch riders.

   Each cohort was divided into centuries; as the name implies, a century contains approximately 100 men, but through historical development the absolute size of a century was variable. In 67 CE nine of the cohorts were divided into six centuries of about 80 men each, but the first cohort, the largest, consisted of five centuries of double the usual size, about 160 men each. Thus there were in all 59 centuries in a legion.

   The leader of a century was a centurion. The rank was roughly equivalent to captain in today's US army. Thus there were six centurions in the cohorts numbered 2 through 10, and presumably the cohort as a whole was commanded by the centurion with the highest seniority. The first cohort, with the double-sized centuries, held five centurions, and these outranked all the other centurions in the legion. The highest centurion of these five was the Primus pilus.

   Ranked above the centurions were six tribunes. These were men from the equestrian class, the second highest class in the Roman aristocracy, underneath the senatorial class. One tribune was senior in rank to the other five, and was second in command of the legion; he was called the tribunus laticlavius, and was appointed to the post by the provincial governor. He often had no prior military experience; the position was a stepping stone on the way to an administrative or political career. Just under the laticlavius was the camp prefect, the third-highest ranking officer in the legionary, who was in charge of equipment and transportation.

   The commander of the legion was the legate (legatus legionis), a senator appointed by the emperor himself. The legate might also be a provincial governor, as in the case of Cestius Gallus.

  Each legion had a standard that symbolized it, an eagle, which was a pole with the figure of an eagle at the top, made of gold. In addition a legion carried standards holding a portrait of the emperor, special flags, and possibly a legion symbol. These standards were objects of worship in the official religion of Rome. For this reason, when legionary standards were introduced into Jerusalem under Pontius Pilate a riot ensued and Pilate was forced to remove them. According to the Roman historian Suetonius, when Cestius Gallus and the Twelfth Legion was defeated the Judaeans captured their eagle, an act of utter humiliation for any legion.

   Besides the legions, the Roman Army consisted of auxiliary units, locally organized cohorts that did not necessarily consist of Roman citizens; citizenship was granted after completing 25 years of service. The most important auxiliary units were the armored horsemen of the cavalry. Long experience had taught Rome that the best cavalry were those recruited from the inhabitants of the area where the unit was stationed. Cavalry units were divided into regiments (alae) of about 500 men, and each regiement was in turn divided into smaller units called turmae consisting of 32 men. The commander of a turma was a decurion.

Flavius Josephus Home Page