Squad
From Halopedia, the Halo wiki
A squad is a military unit used by the UNSC Marine Corps in the organisation of its combat personnel. In the UNSC Marine Corps, a squad can consist of anywhere between eight to thirteen members[1][2], and can be further divided into Fireteams for combat operations.
Composition
The UNSC Marine Corps does follow the general structure used by the 20th and 21st Century US Marine Corps, although exact numbers differ. Normally, a squad is composed of three Fireteams of four or five Marines under the command of a non-commissioned officer, usually a Corporal. A Sergeant[3] commands the squad as a whole.
The UNSC may use a smaller system for Special Forces groups[4] such as the ODST and Naval Special Warfare units.
Squads within a platoon are numbered i.e. First Squad, Second Squad, and so forth, with a Platoon normally composed of at least two Squads, often three or four.
