Organization of the United States Marine Corps

The United States Marine Corps is organized within the Department of the Navy, which is led by the Secretary of the Navy (SECNAV). The most senior Marine commissioned officer is the Commandant of the Marine Corps, responsible for organizing, recruiting, training, and equipping the Marine Corps so that it is ready for operation under the command of the unified combatant commanders. The Marine Corps is organized into four principal subdivisions: Headquarters Marine Corps, the Operating Forces, the Supporting Establishment, and the Marine Forces Reserve.
The Operating Forces are further subdivided into three categories: Marine forces assigned to Unified Combatant Commands, Marine Corps Security Forces guarding naval installations, and Marine Security Guard detachments at American embassies. Under the "Forces for Unified Commands" memo, Marine forces are assigned to each of the regional unified combatant commands at the discretion of the Secretary of Defense and with the approval of the President. Since 1991, the Marine Corps has maintained component headquarters at each of the regional unified combatant commands.
Marine Corps Forces are further divided into Marine Forces Command (consisting of II Marine Expeditionary Force) and Marine Forces Pacific (I Marine Expeditionary Force and III Marine Expeditionary Force). The commander of the former also serves as commanding general for Fleet Marine Force, Atlantic, Marine Corps Forces, Europe, Marine Corps Forces, South, Marine Corps Forces, Strategic, and Marine Corps Installations East; while the latter serves as commander of Fleet Marine Force, Pacific, Marine Forces Central Command, and Marine Corps Installations West.
The Supporting Establishment includes Combat Development Command, Recruit Depots, Marine Corps Logistics Command, Marine Bases & Air Stations, Marine Corps Recruiting Command, and the United States Marine Band.
Relationship with other uniformed services.
Since the U.S. Marine Corps and the U.S. Army both believe that their combat capabilities overlap each other, they have both historically viewed the other branch as encroaching on their capabilities and have competed for money, missions, and fame. Most significantly, in the aftermath of World War II, Army efforts to restructure the American defense establishment involved the dissolution of the Marine Corps and the folding of its capabilities into the other services. Leading this movement were such prominent Army officers as General Dwight Eisenhower, who later became the President of the United States, and Army Chief of Staff George C. Marshall.
The Marine Corps is a branch of the Department of the Navy along with the U.S. Navy. Both the Chief of Naval Operations (CNO) and Commandant of the Marine Corps (CMC), heads of their respective services, report directly to the Secretary of the Navy (SECNAV). As a result, the Navy and Marine Corps have a close relationship, more so than with other branches of the United States Armed Forces. Recent whitepapers and promotional literature have commonly used the phrase "Navy-Marine Corps Team".
 This relationship stems from the Navy providing transport, logistical, medical, and religious service as well as combat support to put Marine units into the fight where they are needed. Conversely, Marines are responsible for conducting land operations to support naval campaigns, including the seizure of naval and air bases. All Marine Aviation programs except for specific command and control and air defense programs are funded by the Navy. Marine Corps officers are assigned to the Office of Chief of Naval Operations (OPNAV) Air Warfare Branch (N98) to represent Marine Aviation interests and serve as "action officers" (viz., staff members). By Congressional mandate, the OPNAV Director, Expeditionary Warfare Branch (N95) is filled by a Marine general.
The Marine Corps cooperates with the Navy on many institutional support services. The corps receives a significant portion of its officers from the United States Naval Academy and Navy Reserve Officer Training Corps (NROTC), which are partially staffed by Marines. Marine Corps drill instructors contribute to training naval officers in Officer Candidate School. Marine aviators are trained in the Naval Aviation training pipeline, and utilize naval-weapons and test-pilot schools. Currently, Navy aircraft carriers deploy with a Marine Hornet squadron alongside Navy squadrons. The Navy's Blue Angels flight team includes at least one Marine pilot and is supported by a Marine C-130 Hercules aircraft and crew.
Since the Marines do not train chaplains or medical personnel, officers and enlisted sailors from the Navy fill these roles. Some of these sailors, particularly Hospital Corpsmen, generally wear Marine uniforms emblazoned with the Marine insignia but US Navy name tags in order to be distinct to compatriots but indistinguishable to enemies. The Marines also operate a network security team in conjunction with the Navy. Marines and sailors share the vast majority of branch-specific awards, with Marines earning the Navy Cross, the highest honor awarded short of the Medal of Honor (which Marines also are awarded, in the Navy version of the Medal of Honor), and other like medals; while an example of the few Marine-only awards is the Good Conduct Medal.
Marine Air-Ground Task Force (MAGTF).
Today, the basic framework for deployable Marine units is the Marine Air-Ground Task Force (MAGTF), a flexible structure that can vary in size. A MAGTF is composed of four elements: the command element (CE), the ground combat element (GCE), the aviation combat element (ACE) and the logistics combat element (LCE). A MAGTF can operate independently or as part of a larger coalition. It is a temporary organization formed for a specific mission and dissolved after completion of that mission.
The MAGTF structure reflects a strong tradition in the Corps towards self-sufficiency and a commitment to combined arms, both essential assets to an expeditionary force often called upon to act independently in discrete, time-sensitive situations. The history of the Marine Corps as well has led to a wariness towards relying too much on its sister services, and towards joint operations in general.
A MAGTF varies in size from the smallest, a Marine Expeditionary Unit (MEU), based around a reinforced infantry battalion and a composite squadron, up to the largest, a Marine Expeditionary Force (MEF), which ties together a Division, an Air Wing, and a Logistics Group under a MEF Headquarters Group.
The three Marine Expeditionary Forces are:
Marine Expeditionary Unit (MEU).
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:
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 , , and an ), 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.
Ground Combat Elements (GCE).
The basic organization of Marine Corps infantry units follows the "rule of threes", which places three subordinates under a commander, not counting support elements. 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".
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:
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.
Aviation combat element (ACE).
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:
The four Marine aircraft wings are: 
Logistics Combat Element (LCE).
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:
Marine Corps Special Operations Components.
Although the notion of a Marine special warfare contribution to the U.S. Special Operations Command (USSOCOM) was considered as early as the founding of USSOCOM in the 1980s, it was resisted by the Marine Corps. Then Commandant Paul X. Kelley expressed the popular belief that Marines should support Marines, and that the Corps should not fund a special warfare capability that would not support Marine operations. However, resistance from within the Marine Corps dissipated when Marine leaders watched the Corps' "crown jewels"—the 15th and 26th MEU (Special Operations Capable) {MEU(SOC)s}—sit on the sidelines during the early stages of Operation Enduring Freedom while other special warfare units led the way. After a three-year development period, the Marine Corps agreed in 2006 to supply a 2,700-strong unit, Marine Forces Special Operations Command (MARSOC), which would answer directly to USSOCOM.
Marine Special Operations Command.
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.
The three Marine Special Operations Battalions (MSOBs) are:
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).
Marine Corps (Special Operations Capable) forces.
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.