The legions of the late Republic were, structurally, almost entirely heavy infantry. The legion's main sub-unit was called a cohort and consisted of approximately 480 infantrymen. The cohort was therefore a much larger unit than the earlier maniple sub-unit, and was divided into six centuries of 80 men each. Each century was separated further into 10 "tent groups" of 8 men each. The cavalry troops were used as scouts and dispatch riders rather than battlefield cavalry. Legions also contained a dedicated group of artillery crew of perhaps 60 men. Each legion was normally partnered with an approximately equal number of allied (non-Roman) troops.
What designation of troops was considered to make up the majority of a legion?
cohort