Fireteam

Military organization
Typical units	Typical numbers	Typical commander
fireteam	3–4	corporal
squad/ section	8–12	sergeant
platoon	15–30	lieutenant
company	80–150	captain/major
battalion/ cohort	300–800	lieutenant colonel
regiment/ brigade	2,000–4,000	colonel/ brigadier general
division/ legion	10,000–15,000	major general
corps	20,000–40,000	lieutenant general
field army	80,000+	general
army group	2+ field armies	field marshal/ five-star general
region/ theater	4+ army groups	Six-star rank

A fireteam is a small military sub-subunit of infantry designed to optimize "bounding overwatch" and "fire and movement" tactical doctrine in combat. Depending on mission requirements, a typical fireteam consists of 4 or fewer members; an assistant automatic rifleman, an automatic rifleman, a rifleman, and a designated team leader; the role of each fireteam leader is to ensure the fireteam operates as a cohesive unit. Two or three fireteams are organized into a squad or section in coordinated operations, which is led by a squad leader.

Military theorists consider effective fireteams as essential for modern professional militaries as they serve as a primary group. Psychological studies by the United States Army have indicated that a soldier's' survivability and the willingness to fight is more heavily influenced by the desire to both protect and avoid failing to support other members of the fireteam than by abstract concepts or ideologies. Historically, nations with effective fireteam organization have had significantly better performance from their infantry units in combat than those limited to operations by traditionally larger units.

Fireteams are the second smallest organized unit in the militaries that use it; the smallest being three or fewer soldier support or specialist teams (such as anti-tank teams, HMG teams, mortar teams, sniper teams, EOD teams, or military working dog teams) that are designed to operate independently.

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Wikipedia