Roman soldiers were divided into two main types — legionaries (citizens of Rome) and auxiliaries from auxiliary troops. In the late Republic era, eight legionnaires made up the Contubernium led by a Decanus and occupied one tent in the camp. 10 Contubernium (80 legionaries) united into a centuria with their signifier — standard bearer, the tesserarius, who had the duties of the chief of the guard, the centurion commander and his assistant- “option”. Six centuriae (6 × 80) created a cohort, and 10 cohorts with a cavalry of equites riders of 120 people formed a legion, the largest military formation in the army of Rome.
Each legion received an aquila symbol in the form of an eagle, for which the aquilifer (bearer) was responsible. The cohorts in the legion were numbered from 1 to 10 and the 1st cohort had actually doubled the composition of five centuriae each of 160 people. The centurions of the 1st cohort were given a higher status than in other cohorts, and primipilus — the centurion of the 1st centurium of the 1st cohort — was the senior among other centurions and the actual assistant of the legion commander. Also there was a non-command post of the prefect of the camp in the legion, who usually was promoted from the centurion and who was responsible for the rear services.
There were seven people in the Legion’s command: the legate commander, as well as six tribunes — the Tribunus laticlavius, who was the second after the legate in the hierarchy, and five military tribunes — angusticlavia. The post of laticlavius, in fact, was not military — this representative of the Senate of Rome underwent a military internship, necessary for a further political career. Unlike the Angusticlavia, he did not command in the battle. The total combat strength of the legion was approximately 6,000.
The auxiliary cohorts and alae of archers, slingers, cavalry were recruited from representatives of the peoples conquered by Rome, taking into account their traditional strengths and could have different numbers. The cohorts of auxiliary infantry had the same organization as in the legion — there were 480 soldiers excluding commanders, but the similarities ended here — they did not group into legions and did not have a legate, but were led by the prefect. Having properly served in the auxiliary cohort for 25 years, the warrior could count on land allotment, retirement and Roman citizenship for himself and his descendants.