Legionary/auxiliary cavalry. 3 riders plus 3 horses
A Roman legion included a small ala or cavalry unit.
Auxiliary cohorts were also divided into centuriae, ranked in order of seniority. The centurion commanding the 1st centuria was known as the centurio princeps (“leading centurion”) and was the 2nd-in-command of the cohort after the praefectus. In the cavalry, the equivalent rank was the decurio (decurion), in command of a turma (squadron) of 30 troopers. Again, the decurion of the 1st turma was designated the decurio princeps.
It appears that many auxiliary centuriones and decuriones were members of native provincial aristocracies who were directly commissioned. Auxiliary centurions risen from the ranks were thus probably less predominant than in the legions. Those rising from the ranks could be promotions from the legions as well as from the regiment’s own ranks. In the Julio-Claudian period, auxiliary centurions and decurions were a roughly equal split between citizens and peregrini, though later citizens became predominant due to the spread of citizenship among military families.