United States Marine Corps Chain of Command and Mission

What Is the Mission of the USMC?

General Neller
Commandant Of Marines.


The Marine Corps is organized as a “force in readiness” to support national defense or humanitarian needs all over the world. Deploying for combat as a combined-arms Marine Air/Ground Task Force (MAGTF), the Marine Corps provides the National Command Authority with a military force with a multitude of operational options.

The USMC Mission

The primary mission of the Marine Corps is to provide Fleet Marine Forces of combined arms together with supporting air components, for service with the fleet. The USMC is organized as a “rule of three”. The Marine Corps minimum peacetime structure shall consist of not less than three combat divisions and three aircraft wings, and land combat, aviation, and other services as needed. The Marine Corps maintains a fourth Marine division and aircraft wing in reserve.

The rule of three is passed down the chain of command as well. Basically, each Marine has three things to worry about. Three men to a fire team commanded by a Corporal (so there are actually a total of four on the team when you count the team leader). Three fire teams to a rifle squad commanded by a sergeant. Three rifle squads to a platoon commanded by a Lt. Three rifle platoons to a company commanded by a Capt. Three companies to a battalion commanded by a Lt Colonel and so on as listed below:

  • Team: Four individual Marines assigned to a specific team (Three team members, plus the team leader).
  • Squad: Three Teams are assigned to a specific squad.
  • Platoon: Three squads are usually assigned to a specific platoon.
  • Company (or Battery): Three platoons are assigned to a Company (sometimes called a battery). The Company/battery is the lowest level of command with a headquarters element (for example, a Company Commander, or Company First Sergeant).
  • Battalion: Three companies/batteries are assigned to form a battery a battalion.
  • Regiment: Three battalions form a Regiment (Sometimes called a Brigade).
  • Division: Three Brigades are assigned to make up a Division.
  • Marine Corps: Three or more divisions make up the Marine Corps.


In addition to the above, there are also MEUs (Marine Expeditionary Unit). With a strength of about 2,200 personnel, the MEU is normally built around a reinforced battalion, a composite aircraft squadron, and by a MEU Service Support group. Commanded by a colonel, the MEU is employed to fulfill routine forward deployments with fleets in the Mediterranean, the Western Pacific, and periodically, the Atlantic and Indian Oceans. The MEU is deployed on up to four Naval amphibious ships. The ground combat element (GCE) is the battalion landing team (BLT), an infantry battalion reinforced with artillery, amphibious assault vehicles, light armored reconnaissance assets and other units as the mission and circumstances require. The aviation combat element (ACE) is a Marine Medium Helicopter Squadron augmented with four types of helicopters into a composite squadron. These units include CH-53E "Super Stallions," CH-46E "Sea Knights," UH-1N "Hueys," and AH-1W "Super Cobras." Ace assets may also include the fixed-wing aircraft such as the AV-8B "Harrier" jet. The combat service support element is the MEU Service Support Group (MSSG) formed primarily from force service support groups assets. The MSSG contains all the logistics specialists necessary to keep the GCE, ACE and organic equipment functioning. Included within the MSSG are medical, dental, maintenance, engineering, and other technical experts. The command element (CE) provides command and control of the other three elements. In addition to the MEU commander and his supporting staff, the CE includes specialized detachments providing a direct action capability, naval gunfire liaison capability, reconnaissance, and surveillance and specialized communications and electronics warfare capabilities.

Marine Aviation

The Marines structure their aviation commands a little differently. The structure for aviation commands are:

  • Squadron: (applied to flying & non-flying units). In aircraft squadrons, the number of aircraft varies from 4 - 24, depending on the type of squadron. Non-flying squadrons include Marine Aviation Logistics Sqns (supply), Marine Wing Support Sqns (construction), Marine Air Control Sqns (air defense), Marine Air Support Sqns (Airfield control), Marine Tactical Air Command Sqns, Marine Wing Communications Sqns, Marine Wing Headquarters Sqns (Admin).
  • Group: (3 or more squadrons) Includes Marine Aircraft Group (MAG), Marine Wing Support Group (MWSG), Marine Air Control Group (MACG). The MAGs are usually all helo or all fixed-wing (MAG-36 in Okinawa has a KC-130 sqn attached)
  • Wing: 3+ Groups. 2 or more MAGs + MWSG, MACG.

The Actual Chain of Command

There are two parallel chains of command within the Marine Corps: Service and Operational. The Service Chain of Command is used for things that are specifically inherent to the Marine Corps. The top portion of the service chain is listed below:

Service Chain of Command

President / Secretary of Defense / Secretary of the Navy / Commandant of the Marine Corps

The Operational Chain of Command is used to direct forces in conjunction with operational or functional missions. Often times this involves other services outside the Marine Corps. The Operational Chain of command break down is listed below:

Operational Chain of Command

President - Secretary of Defense - Commanders of Combatant commands

Four Major Commands of the USMC

The Marine Corps is divided into four broad categories and overseen by Headquarters, U.S. Marine Corps (HQMC). HQMC consists of the Commandant of the Marine Corps and his command staff agencies that assist him in the operational and administrative capabilities. The Commandant is directly responsible to the Secretary of the Navy for the following subordinate commands within the USMC.

U.S. Marine Corps Forces Command (MARFORCOM) commands all Marines in CONUS as well as in charge of all Marine forces in the Southern and European theater (MARFORSOUTH and MARFOREUR) – located in Norfolk Va.

U.S. Marine Corps Forces, Pacific (MARFORPAC) Commands all Marine Corps operational and shore-based commands in the Pacific theater – located in Hawaii.

The United States Marine Corps Reserve (MARFORRES) is responsible for providing trained units in a reserve status that can be activated in time of war, national emergency, contingency operations and relieve active duty Marines in high op tempo situations / long deployment cycles.

The Marine Corps supporting establishments consists of Marine Corps Recruiting Command - Marine Corps Combat Development Command - Marine Corps Systems Command - Training activities and formal schools.