In a Roman army an optio (Latin: optiō, from optāre, 'to choose', so-called because superior officers chose the optio; pl.: optiones) held a rank in a centuria (century) similar to that of an executive officer. The main function of an optio was as an optio centuriae, the second-in-command of a century, although there were many other roles an optio could fulfil. Optiones carried out vital roles in the Roman military. An optio was stationed at the rear of the ranks to keep the troops in order.
https://en.wikipedia.org/wiki/Optio
In a Roman army an optio (Latin: optiō, from optāre, 'to choose', so-called because superior officers chose the optio; pl.: optiones) held a rank in a centuria (century) similar to that of an executive officer. The main function of an optio was as an optio centuriae, the second-in-command of a century, although there were many other roles an optio could fulfil. Optiones carried out vital roles in the Roman military. An optio was stationed at the rear of the ranks to keep the troops in order.
