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. The Marines grew to a field strength of six divisions during World War II, including the 5th Marine Division and the 6th Marine Division. Both were disbanded after the war.
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. Chapter 7, The Marines' Push Button 113-119
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).Action Officer: Staff Writing, Action Officer (Definition), U.S. Army Training and Doctrine Command, Preface. 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 Naval 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: I Marine Expeditionary Force located at Camp Pendleton, California II Marine Expeditionary Force located at Camp Lejeune, North Carolina III Marine Expeditionary Force located at Camp Courtney, Okinawa, Japan
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 an 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 , , and a ), 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 Expeditionary Strike Group (ESG) in its entirety or detach units as needed, though the MEU usually remains aboard the ships of the ESG to use those 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".
A fire team, is the basic element of the GCE. It consists of four Marines: 1x team leader, corporal (E-4) (M4/M16 with attached M203) 1x rifleman, rank of Pvt/E-1 (M4/M16) 1x assistant automatic rifleman, rank of PFC/E-2 (M4/M16) 1x 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: 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).