An army unit of 120 soldiers is known as what?

The correct answer is a "Cohort." In a Roman military context, a cohort typically consisted of around 480 soldiers, divided into six centuries of 80 soldiers each. However, in various situations, including formations and tactical adaptations, numbers could shift, and there could be variations based on specific historical periods or military reforms.

In ancient Rome, a century represented a unit of roughly 100 soldiers, which would indicate that an army unit of 120 soldiers exceeds the common definition of a century but does not align with the larger structure of a cohort or legion. A maniple was a smaller unit that existed before the cohort system and generally consisted of about 120 soldiers, but it was ultimately replaced by the cohort as the primary unit of the Roman army. Thus, the terminology varies, but the cohort is more representative of military structure in Rome for a larger scale, while the maniple was an earlier formation.

Understanding these distinctions provides clarity on how different units were organized within the Roman Empire and their respective sizes and functions in military tactics.