Organization of the United States Marine Corps

Each of the seven MEUs are assigned to their respective Navy fleet as components of the Fleet Marine Force: three to the Atlantic Fleet (based at Camp Lejeune), and four to the Pacific Fleet (three based at Camp Pendleton and one in Okinawa). Each is commanded by a colonel with a combat arms background thus, infantry or aviator. The MEU components consist of a command element, ground combat element, aviation combat element, and a logistics combat element each commanded by a lieutenant colonel. MEU rotations are staggered so that while one MEU is on deployment, another is training to deploy, and one is standing down to refit and exchange units. Each MEU is trained during its workup evolution to perform special operations tasks and is then designated as a MEU(SOC) (Special Operations Capable). Each MEU can tailor its equipment to the expected tasking.

MEU Components:

• Command Element
• Aviation Combat Element (a composite squadron organized with a variety of platforms)
• Ground Combat Element (an infantry battalion, known as the "Battalion Landing Team", task-organized and reinforced with other organic elements such as armor, artillery, and engineers)
• Logistics Combat Element (provides the six functional areas of combat service support to the MEU)

Typically, a MEU falls under the operational control of but no longer deploys as part of an Expeditionary Strike Group (which replaced the Amphibious Ready Group), composed of Navy amphibious ("L-class") ships (a LHD or LHA to serve as the flagship of the Amphibious Squadron, LSD(s), and LPD(s) that embark the MEU), escort ships (such as the Arleigh Burke-class destroyer, Ticonderoga-class cruiser, and an Los Angeles-class submarine), and the requisite landing vehicles to transport the MEU ashore, such as the LCAC, LCU surface craft, Amphibious Assault Vehicle (though the MEU can utilize its helicopter lift assets embarked aboard the LHD or LHA). The theater component commander can use the ESG in its entirety or detach units as needed, though the MEU usually remains aboard the ships of the ESG to use it as their principal base of operations. This ability to remain at sea and "over the horizon" until called is a unique capability of the ESG/MEU.

The basic organization of Marine Corps infantry units follows the "rule of threes", which places three subordinates under a commander, not counting support elements.[7] The organization and weapons are from the Marine Corps Table of Organization and Equipment (TOE) standard. Note that these are principles, but according to manpower and mission needs units can deviate from the TOE (e.g. with four subordinate units instead of three, or a commander who is a rank above or below the rank specified). Supporting units will have their own organization and equipment, but generally also follow the "rule of threes".

• A fire team, is the basic element of the GCE. It consists of four Marines: the team leader, corporal (E-4) (M4/M16 with attached M203), one rifleman, rank of Pvt/E-1 (M4/M16), one assistant automatic rifleman, rank of PFC/E-2 (M4/M16), and one automatic rifleman, rank of LCpl/E-3 (M27 Infantry Automatic Rifle or M249 light machine gun).
• A rifle squad, usually led by a sergeant, is made up of three identical fire teams.
• A rifle platoon, commanded by a 2nd or 1st lieutenant, consists of three rifle squads, and a headquarters element made up the platoon commander, a platoon sergeant, a platoon guide, and a messenger. (One or more Navy Medical Corpsman are usually attached to the platoon from the battalion's medical platoon.) The platoon sergeant, usually a staff sergeant, advises the commander and serves as the second-in-command. The platoon guide, usually a sergeant, serves as the assistant platoon sergeant. A rifle platoon is capable of integrating attachments from the weapons platoon (e.g., assault squad or machine gun squad) and may include a two-man mortar forward observer team attached from the battalion's 81-mm mortar platoon.

A weapons platoon, usually commanded by a 1st lieutenant and assisted by a gunnery sergeant as the platoon sergeant, will substitute for the rifle squads:[8][9]

• a 60 mm mortar section, with a staff sergeant as section leader and consisting of three mortar squads, with each squad led by a corporal as squad leader and containing one M224 mortar and three Marines.;
• an assault section, led by a sergeant as section leader and consisting of three assault squads, with each squad led by a corporal and containing two teams, with each team consisting of a SMAW and two Marines; and
• a medium machine gun section, led by a staff sergeant as section leader and consisting of three machine gun squads, with each squad led by a sergeant as squad leader and containing two teams, which each team led by a corporal as team leader and containing one M240G and three Marines).

• A rifle company, commanded by a captain as the commanding officer (CO) and assisted by a 1st lieutenant as the company executive officer (XO) who serves as second-in-command, consists of three rifle platoons, a weapons platoon, and a company headquarters, which, in addition to the two officers, includes the first sergeant, company gunnery sergeant, property NCO, and a messenger/driver.

A weapons company, commanded by a major and assisted by a captain as XO, will substitute for the rifle platoons an 81 mm mortar platoon, an anti-armor platoon, and a heavy machine gun platoon. In deference to the more extensive training requirements and complicated tactical considerations necessitated by the crew-served weapons employed by the weapons company, its platoon commanders are usually 1st lieutenants and the platoon sergeants are gunnery sergeants. The company headquarters includes a master sergeant as the operations chief (in lieu of the company gunnery sergeant) and an additional messenger/driver.

A headquarters and service company, commanded by a captain and assisted by a 2nd or 1st lieutenant as the XO, contains the battalion headquarters, which includes the command section (including the battalion CO, battalion XO, and the sergeant major), the executive staff sections (S-1, S-2, S-3, S-4, & S-6), and the chaplain section. The company consists of a company headquarters section, a scout sniper platoon, a communications platoon, a service platoon, and a medical platoon.

• An infantry battalion, commanded by a lieutenant colonel and assisted by a major as the battalion XO, consists of three rifle companies, a weapons company, and a headquarters and service company.
• An infantry regiment, commanded by a colonel and assisted by a lieutenant colonel as the regimental XO, consists of three battalions, and a regimental headquarters company.
• A Marine division, commanded by a major general as the commanding general (CG) and assisted by a brigadier general as the assistant division commander, usually consists of three infantry regiments, an artillery regiment, several separate battalions (i.e., reconnaissance, assault amphibian, tank, light armored reconnaissance, and combat engineer), and a headquarters battalion.

The unit designation brigade is only used in the Marine Corps in the form of a Marine Expeditionary Brigade (MEB), an intermediate sized Marine Air Ground Task Force (MAGTF). The MEB is usually commanded by a brigadier general as CG, who is assisted by a colonel as the chief of staff (CoS) of the MEBs general staff and who is "dual-hatted" as the MEBs second-in-command. The MEB consists of three regimental equivalent combat elements (ground, air, and logistics) and a battalion-sized headquarters element. The ground combat element (GCE) consists of a Regimental Combat Team (RCT), which is a heavily reinforced infantry regiment (including field artillery, infantry reconnaissance, amphibious assault vehicle, tank, light armored reconnaissance, and combat engineer units), itself roughly equivalent to a US Army Infantry Brigade Combat Team. The air, or aviation, combat element (ACE) consists of a composite Marine Aircraft Group containing several helicopter, tilt rotor, tactical fixed wing, and UAV squadrons and/or detachments, as well as aviation ground support, command and control, and air defense units. The MAG is roughly equivalent in terms of numbers of aircraft and personnel to a US Army Combat Aviation Brigade. The logistics combat element (LCE) consists of a combat logistics regiment (CLR) consisting of combat logistics battalions (CLB), and specialized logistical companies and detachments to support the MAGTF. The headquarters, or command, element (CE) consists of specialized companies and detachments that perform various command, control, communications, surveillance, reconnaissance, intelligence, law enforcement, and liaison functions.

Two unique unit designations to the Marine Corps are Marine Expeditionary Unit (MEU) and Marine Expeditionary Force (MEF) MAGTFs. The MEU is the smallest MAGTF and consists of approximately 2,200 personnel. Commanded by a colonel with a lieutenant colonel as XO, it consists of a battalion landing team (BLT), a reinforced infantry battalion, as its GCE and a Marine Medium Tiltrotor Squadron (VMM), reinforced with detachments of helicopters, tactical fixed wing, and UAV aircraft, as well as aviation ground support, command and control, and air defense detachments, as its ACE. The MEU's LCE consists of a CLB, and its CE is a company-sized version of the MEB's battalion-sized headquarters group. The MEF is the Marine Corps's equivalent tactical command level to an army corps. The MEF has a lieutenant general as CG with a major general as deputy CG. The MEF consists of a Marine Division as its GCE, a Marine Aircraft Wing as its ACE, a Marine Logistics Group as its LCE, and a regimental-sized MEF Headquarters Group (MEF HQG) as its CE.

Battalions, and larger units commanded by a field grade officer, have an executive officer as the second-in-command and an executive staff consisting of: Manpower / Administration & Personnel (S-1), Intelligence (S-2), Operations, Plans & Training (S-3), Logistics (S-4), Civil Affairs (wartime only) (S-5), and Communications (S-6) sections. Units commanded by a general officer have a chief of staff and a general staff in which the staff sections are designated as G-1, G-2, etc. Battalions and larger units replace the company (and battery) first sergeant with a sergeant major, as the senior enlisted advisor to the unit commander.

The four Marine divisions are:

• 1st Marine Division at Camp Pendleton, California
• 2nd Marine Division at Camp Lejeune, North Carolina
• 3rd Marine Division at Camp Courtney in Okinawa, Japan
• 4th Marine Division, a reserve unit headquartered in New Orleans, Louisiana, with units scattered throughout the United States.

In World War II, two more Marine Divisions were formed: the 5th and 6th, which fought in the Pacific War. These divisions were disbanded after the end of the war. The 5th Marine Division was reactivated for service in Vietnam but was disbanded again in the early 1970s.

The mission of Marine Corps aviation is to provide the MAGTF commander with an aviation combat element (ACE) capable of conducting air operations in support of the seizure and defense of advanced naval bases, and conducting such land operations as may be directed by the Joint Force commander.

The ACE supports the MAGTF by providing the six functions of Marine aviation: assault support, anti-air warfare, offensive air support, electronic warfare, control of aircraft and missiles, and aerial reconnaissance.

Aviation units are organized into:

• Squadrons of 5–27 aircraft (depending upon aircraft type), tactically organized into sections of 2–3 aircraft and divisions of 2–3 sections, as needed for mission requirements (squadrons may also be organized with one or more detachments, containing two or more aircraft, for deployment requirements), commanded by a lieutenant colonel
• Groups of 4–12 squadrons (average of 7 squadrons per group) and a group headquarters, commanded by a colonel
• Wings of two or more Marine aircraft groups (MAG), a Marine air control group, and Marine wing headquarters squadron, and a Marine wing headquarters, commanded by a major general as the wing CG with a brigadier general as the assistant wing commander.

The four Marine aircraft wings are:

• 1st Marine Aircraft Wing at Marine Corps Base Camp Smedley D. Butler, Okinawa, Japan
• 2nd Marine Aircraft Wing at Marine Corps Air Station Cherry Point, North Carolina
• 3rd Marine Aircraft Wing at Marine Corps Air Station Miramar, California
• 4th Marine Aircraft Wing, a reserve unit, headquartered in New Orleans, Louisiana, with units scattered throughout the United States

Beyond logistics (i.e., motor transport, supply, and maintenance), the LCE provides engineer support (i.e., heavy equipment, bulk fuel and water, utilities, bridging, explosive ordnance disposal, and reinforcement to combat engineer units), medical and dental personnel, and other specialized units (e.g., aerial delivery and landing support).

The four Marine logistics groups are:

• 1st Marine Logistics Group at Camp Pendleton, California
• 2nd Marine Logistics Group at Camp Lejeune, North Carolina
• 3rd Marine Logistics Group at Camp Kinser, Okinawa, Japan
• 4th Marine Logistics Group, a reserve unit, headquartered in New Orleans, Louisiana, with units scattered throughout the United States.

The Marine Special Operations Command is the Marine Corps's special operations component that reports to United States Special Operations Command (USSOCOM). Currently, MARSOC trains, organizes, equips and, when directed by the Commander, USSOCOM, deploys task organized, scalable, and responsive U.S. Marine Corps special operations forces worldwide in support of combatant commanders and other agencies.

The MSOAG, formerly the FMTU, has been operating since 2005, before MARSOC formally existed. MARSOC was formally activated during a February 24 ceremony at Camp Lejeune, N.C., where MARSOC is now headquartered. Fox Company, 2nd Marine Special Operations Battalion, was the first of the Marine Special Operations Battalions' companies to activate in the Spring of 2006. Drawing its manpower from the core of 2nd Force Reconnaissance Co., Fox Company's creation came at the expense of 2nd Force Reconnaissance Co., which stood down upon the transfer of its platoons to both MARSOC's 2nd Marine Special Operations Battalion, and a new company (Delta) of 2nd Reconnaissance Battalion.

• A fireteam is the basic element of the Marine Special Operations Regiment. Like fireteams in the infantry, MSOR fireteams consist of four Marines; a team leader/grenadier, an automatic rifleman, an assistant automatic rifleman and a rifleman.
• A Marine Special Operations Team (MSOT) is made up of three fireteams, in addition to a captain as a team leader, a radio operator and a Navy corpsman.
• A Marine Special Operations Company (MSOC), made up of four MSOTs and commanded by a major.
• A Marine Special Operations Battalion, made up of four MSOCs and commanded by a lieutenant colonel.

The three Marine Special Operations Battalions (MSOBs) are:

• 1st Marine Special Operations Battalion at Camp Pendleton, California.
• 2nd Marine Special Operations Battalion at Camp Lejeune, North Carolina.
• 3rd Marine Special Operations Battalion at Camp Lejeune, North Carolina.

MARSOC also contains a Marine Special Operations Support Group (SOSG) that trains, equips, structures, and provides specially qualified Marine forces, including operational logistics, intelligence, multipurpose canines, Firepower Control Teams and communications support in order to sustain worldwide special operations missions as directed by Commander, U.S. Marine Corps Forces Special Operations Command (COMMARFORSOC).

The Special Operation Capable forces are the units of the Marine Corps that are fully equipped, and prepared for any hostility, or emergency worldwide. Being very co-dependent of the air-ground task force, they are capable of conducting special operations in conventional warfare, and often overlapping in unconventional methods, comparable to other special operations forces of maritime regions. Many special mission tasks are mostly infantry support units, such as reconnaissance, ANGLICO, and others.