UNSC Military Organization

The Organization of the UNSC Military is the way in which the UNSC Navy and UNSC Marine Corps organize their fighting forces into manageable sizes of manpower for use in combat operations. Though there have been many UNSC military units named in the books and games, the exact specifications of the UNSC armed forces organization remains unclear. For a complete list of all known UNSC Military units, see List of UNSC Military Units.
==UNSC Marine Corps==
The large-unit structure of the UNSC Marine Corps appears to mirror the organizational structure of the United States Marine Corps in most distinguishable ways, however the small-unit structure is more unique and in some ways still unclear. A nearly complete chart showing the sourced known structure of the UNSC Marine Corps units can be seen below. As in the case of the United States Marine Corps, the UNSC Marines appear to have a very flexible organization depending on the needs of the mission. The Expeditionary force is listed as the largest deployable unit above a division, but marines also deploy in Marine Expeditionary Brigades (MEB: commanded by a brigadier general and about 16,000 marines and sailors strong) and Marine Expeditionary Units (MEU: commanded by a colonel and about 2,200 marines and sailors strong).
Similarly to the expeditionary force, they each contain a ground combat element, an air combat element, a logistics element, and a command element. The Marine Expeditionary Brigade's Ground Combat Element consists of an infantry regiment reinforced by an artillery battalion, a tank company, a combat engineer company, and reconnaissance company. Its Air Combat Element is a composite air group (the level below air wing) commanded by a colonel and a combat logistics regiment (the level below logistics group) commanded by a colonel. The Marine Expeditionary Unit's Ground Combat Element consists of an infantry battalion reinforced by an artillery battery (the equivalent of a company), a tank platoon, a combat engineer platoon, and a reconnaissance platoon. Its Air Combat Element consists of a composite air squadron (level below air group) commanded by a lt. col. Its Logistics Combat Element consists of a composite logistics battalion (level below logistics regiment) commanded by a lt. col.
To be clear, Divisions, Regiments, Battalions, and corresponding air and logistics units are not permanently assigned to marine expeditionary forces, brigades, and units, but rather formed for specific task forces for a mission. For example, say the UNSC wanted to establish a base on a moon or asteroid but a force or brigade was too large for the job. It would detach an infantry battalion, tank platoon, etc. from its mother infantry division and assign these units to the MEU HQ. After the mission was over they could possibly remain with the MEU or it could be disbanded. Another possibility would be to rotate units out of the MEU back to their parent unit after some time and replace it with a fresh unit. The flexibility and adaptability of the system clearly shown here helps to explain why it has survived for centuries.
Current Halo canon focuses heavily on small unit interactions, with units at any strength higher than a Battalion being only occasionally mentioned and never elaborated upon. This has caused a lack of information regarding the specifics of larger UNSC Marine commands. Small units structure is often referenced indirectly. The below chart shows unit strength and specifics that can be applied to all (as of yet ) known units.
Name 	No. of personnel 	No. of subordinate units 	Unit leader 	Identification Scheme
Expeditionary Force
Halo: Contact Harvest, Page 111	40,000-50,000 	1 Infantry Division, 1 Air Wing (Major Gen), 1 Logistics Group (Brigadier Gen), 1 Headquarters Element	Lieutenant General 	Designated with a number, all Expeditionary Forces in the UNSC are on the same number system. (e.g.- 9th Marine Expeditionary Force)
Division
Halo: Contact Harvest, Page 112	20,000 	
3 Infantry Regiments + 1 Artillery Regiment, 1 Headquarters Battalion, 1 Tank Battalion
1 Reconnaissance Battalion, 1 Combat Engineer Battalion	Major General 	Designated with a number, all Divisions in the UNSC are on the same number system. (e.g.- 21st Marine Division, 105th ODST Division)
Regiment
Halo Graphic Novel	3,200 	3 Infantry Battalions Battalions, 1 Headquarters and Service Company 	Colonel 	Designated with a number, all Regiments in the UNSC are on the same number system. (e.g.- 77th Marine Regiment, 506th Tank Regiment)
Battalion
The Art of Halo	800-1,000 	3 Rifle Companies, 1 Weapons Company, 1 Headquarters and Service Company 	Major
Halo: The Flood, Page 33-Lieutenant ColonelHalo: Contact Harvest, page 112	Receive a numbering within the Regiment, or an independent number for special forces units (e.g.- 7th ODST Battalion)
Company
Halo: First Strike	130Halo: The Flood- 250Halo: Contact Harvest 	3 -6 PlatoonsHalo 3 	Captain
-First Lieutenant 	Designated with a letter from the Phonetic Alphabet. (e.g.- Tango Company, Alpha Company)
Platoon
Halo 2, level Delta Halo (Level)	25Halo-48Halo: Contact Harvest, 	3 - 4 Squads 	Gunnery Sergeant
,Halo 3, level Sierra 117 (Level) Second Lieutenant,Halo: The Flood, page 134 or First LieutenantHalo: The Flood, page 58	Numbered within a Company (e.g.- 1st Platoon)
Combat Team
The Pillar of Autumn (Halo: Combat Evolved level)	16-24Halo: Combat Evolved 	2 Squads 	Sergeant or Staff Sergeant	Designated within Platoon by letter in Phonetic Alphabet
Squad
Halo 3, level Sierra 117	5Halo: Combat Evolved, level The Silent Cartographer, level Truth and Reconciliation-8	3 Fireteams Halo: Combat Evolved, Halo: Contact Harvest 	Corporal
Halo: Combat Evolved, level 343 Guilty Spark-Staff Sergeant	Numbered (using the word, not the number) within a Platoon. (e.g.- 1st Squad, 2nd Squad)
Fireteam	2Halo: Combat Part 2-5 	N/A 	Corporal
Halo: The Fall of Reach, page-Staff Sergeant	Designated with a letter from the phonetic alphabet within a squad, (e.g.- Alpha Team, Fireteam Charlie)
===Exceptions===
The above system seems to fit most stated units of the UNSC armed forces, but not all unit designations are clear. Specifically, the use of unit abbreviation codes make it particularly difficult to properly identify units. An example of this is the unit 3/1 Bravo, seen in Halo: Combat Part 2. "3/1 Bravo" could possibly stand for "Bravo Company, 1st Battalion, 3rd Marine Regiment," however, "Fireteam Bravo, 1st Squad, Third Platoon" is just as reasonable a translation of the code. More complicated codes arose in Halo 3, such as S4/BAG/2/5 and E2-BAG/1/7, which have even more variables.
The only time a unit abbreviation code is translated is page 111 of Halo: Contact Harvest, where M-EDF 9/21/1 is translated as 9th Marine Expeditionary Force, 21st Marine Division, 1st Battalion. This adds further mystery to the scheme, as it apparently skips over the Regimental command and implies that the Battalion is directly subordinate to the Division level headquarters, a fact that no other source has ever stated and does not make sense according to standard military organization.
Unit designations are also deeply convoluted, due to the great use of acronyms which are not used in modern militaries and have not yet been directly spelled out. References have been made to "BAG" units (as seen above) where no modern military designates any type of combat unit with the acronym "BAG," and the many possible meanings of the acronym make it unclear what a "BAG" unit is. Other anomalies include 2BN/3U, where "2BN" is short for 2nd Battalion, but what "3U" stands for is unclear, and only assumed to be "Third Unit." The mentioned 22nd Tactical, (having received no further designation, and could be of virtually any size) and the 105th Drop Jet Platoon (going against the established scheme of not providing permanent designations for Platoons) are even further examples of the confusion caused by clashing sources of information.
==UNSC Navy==
The UNSC Navy command structure has received even less attention than the UNSC Marine Corps. Mentions have been made of Battle Groups containing less than ten vessels being used, but it is unclear if battle groups are permanent assignments for ships or not. Additionally, numbered fleets have been mentioned, but no information about them other than their number designation has been revealed, making it impossible to infer what the UNSC Fleet organization is.
==Sources==