Updated December 11, 2020
Defense Primer: Organization of U.S. Ground Forces
Overview
and a logistics brigade. Army divisions consist of 12,000-
The Army is the U.S. military’s primary ground force. Title
16,000 personnel.
10, Subtitle B, Part I, Chapter 307 of the U.S. Code
addresses the organization of the Army. The Marine Corps
Corps. Corps are commanded by a lieutenant general and
serves as the Navy’s land-based fighting force. Title 10,
include two to five divisions and numerous support
Subtitle C, Part I, Chapter 507, Section 5063 addresses
brigades and commands. Corps have about 40,000-100,000
Marine Corps composition and functions. For the National
personnel. The Marines do not have designated corps,
Guard and Reserves, see CRS In Focus IF10540, Defense
although a Marine Expeditionary Force (MEF) is similar in
Primer: Reserve Forces.
size and also is commanded by a lieutenant general.
Organizational Levels of U.S. Ground
Army. An army is the highest command level in a given
Forces
theater of operations and typically has 100,000-300,000
The Army and Marine Corps are organized as hierarchies of
personnel. It is an element of a joint command structure,
units, with each type of unit commanded by a
with the Army’s component commanded by a general. An
noncommissioned or commissioned officer of a specific
Army’s operational theater is established to support one or
rank. These units are described from smallest to largest.
more corps and includes numerous support brigades and
support commands.
Squad/Team/Section. A squad is led by a sergeant and
consists of 4-12 personnel. Squads can be further divided
Army Brigades
into teams or sections.
According to the Association of the U.S. Army’s (AUSA)
Profile of the United States Army 2018, Army Brigades are
Platoon. A platoon—which is led (Army) or commanded
organized as follows.
(Marines) by a lieutenant and includes varying numbers of
subordinate squads, teams, or sections—may vary from 16
to 50 personnel. Heavy platoons also have armored vehicles
The Brigade Combat Team (BCT) is the basic combined-
(such as tanks or infantry fighting vehicles, depending on
arms building block of the Army. It is a permanent, stand-alone,
the type of platoon).
self-sufficient, and standardized tactical force of about 4,000
soldiers. At present, the Army consists of 58 BCTs, with 31
Company/Troop/Battery. A company is commanded by a
BCTs in the Regular Army (RA) and 27 BCTs in the Army
captain and includes two to five subordinate platoons
National Guard (ARNG).
(usually three or four). It has about 100-200 personnel.
The Army has three types of BCTs: Infantry BCTs (IBCTs),
Cavalry (air or ground reconnaissance units) companies are
Armored BCTs (ABCTs), and Stryker BCTs (SBCTs).
called troops (Army only); artillery and air and missile
Infantry BCTs (IBCTs) include three infantry battalions, a
defense companies are called batteries.
reconnaissance and surveillance cavalry squadron, a field artil ery
battalion, a brigade engineer battalion, and a logistics support
Battalion/Squadron. A battalion is commanded by a
battalion. IBCTs also are organized to be airborne or air-assault
lieutenant colonel and usually includes three to five combat
capable. As of December 2020, the Army has 13 Active
companies and one support company. It has about 500 to
Component and 20 National Guard IBCTs.
900 personnel. Cavalry battalions are called squadrons.
Armored BCTs (ABCTs) include three armor/mechanized
infantry battalions, an armed reconnaissance cavalry squadron, a
Brigade Combat Team/Support
field artil ery battalion, a logistics support battalion, and a brigade
Brigades/Regiment/Group. Army brigades are
engineer battalion. As of December 2020, the Army has 11
commanded by a colonel and generally are configured as a
Active Component and 5 National Guard ABCTs.
brigade combat team (BCT), a functional support brigade
(FSB), or a multifunctional support brigade (MFSB). Each
Stryker BCTs (SBCTs) are centered on the Stryker, an eight-
brigade has about 3,900-4,100 personnel. Army cavalry
wheel-drive armored vehicle. SBCTs consist of three infantry
brigades are called regiments; some types of support
battalions, a cavalry squadron for reconnaissance and target
brigades are called groups. Marine Corps units at this level
acquisition, a field artil ery battalion, a brigade support battalion,
also are called regiments. (The term Marine Expeditionary
a brigade engineer battalion, a military intelligence company, an
Brigade [MEB] refers to a regimental-size task force, which
engineer company, a signal company, an antitank company, and a
is larger than a standard Army brigade).
headquarters company. As of December 2020, the Army has 7
Active Component and 2 National Guard SBCTs.
Division. An Army division is commanded by a major
Functional Support Brigades
general and includes two to five BCTs (usually three), an
aviation brigade, an artillery brigade, an engineer brigade,
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Defense Primer: Organization of U.S. Ground Forces
military operations. MAGTFs consist of command, ground
FSBs are designed to plug into operational formations at the
combat, air combat, and logistics elements.
Army Service Component Command (ASCC), corps, division, or
theater level. Once deployed, these brigades conduct operational
Ground Combat Element (GCE)
or theater-level support. There are several types of FSBs,
The GCE conducts land-based and amphibious operations,
including air defense, artil ery, engineers, military police, cyber,
including offensive, defensive, humanitarian,
signal, explosive ordinance disposal, medical support, and
reconnaissance, and security operations.
aviation.
Multifunctional Support Brigades
Marine Corps Combat Organizations
Similar to FSBs, MFSBs are designed to plug into operational
There are types of MAGTFs: the Marine Expeditionary
formations, but their purpose is to support BCTs. There are five
Force (MEF); the Marine Expeditionary Brigade (MEB);
types of MFSBs: combat aviation, combat support, sustainment,
the Marine Littoral Regiment (MLR); the Marine
fires and battlefield surveil ance, and tactical-level task and
Expeditionary Unit (MEU); and the Special Purpose
support.
MAGTF (SPMAGTF).
Security Force Assistance Brigades (SFABs)
Marine Expeditionary Force
(For more information on SFABs, see CRS In Focus IF10675,
MEFs are the primary warfighting force for larger
Army Security Force Assistance Brigades (SFABs), by Andrew
operations. Consisting of 20,000 to 90,000 Marines and
Feickert.)
Sailors and commanded by a lieutenant general, MEFs are
SFABs are capable of conducting Security Force Assistance at the
composed of a Marine division, aircraft wing, and logistics
tactical (brigade and below) level. The Army is establishing six
group.
SFABs—five in the Active Component and one in the Army
National Guard (ARNG). SFABs consist of about 800 soldiers,
Marine Expeditionary Brigade
with most being officers and noncommissioned officers (NCOs).
MEBs are task-organized for specific missions, and consist
If required SFABs can be expanded into ful y operational BCTs
of a force of up to 20,000 Marines and Sailors, and are
capable of conducting combat operations. In this case, SFAB
commanded by a brigadier general. MEBs have a
personnel would serve as cadres who would accept the
regimental-size ground combat element and are embarked
expansion of personnel and equipment required to transform the
aboard amphibious assault ships.
SFAB into a BCT.
Marine Littoral Regiments
Marine Corps
MLRs are intended to operate and survive in a contested
maritime environment where near-peer countries can
Adapted from the Marine, Air, Ground Task Force
challenge Marines for supremacy in the air or on sea. The
(MAGTF) and MAGTF Composition websites at
MLR will need to able to control local air space, choke
https://www.candp.marines.mil/Organization/MAGTF/;
points or waterways. MLRs are to consist of about 1,800 to
https://www.candp.marines.mil/Organization/MAGTF/MA
2,000 Marines and Sailors, and be comprised of three main
GTF-Composition/; and Types of MAGTFs at
elements: a Littoral Combat Team (LCT), a Littoral Anti-
https://www.candp.marines.mil/Organization/MAGTF/Typ
Air Battalion, and a Littoral Logistics Battalion.
es-of-MAGTFs/
Marine Expeditionary Unit
The Marine Corps is a hybrid service, with units that engage in
MEUs consist of approximately 2,600 Marines and Sailors
combat on the ground and in the air. The Marine Corps
and are a forward-deployed crisis-response force. MEUs
organizes its forces into task forces, each with a command, ground
deploy as part of an amphibious ready group (ARG) and are
combat, aviation combat, and logistics combat element. The largest
commanded by a colonel.
such task force, a Marine expeditionary force (MEF), includes a
Special Purpose MAGTF
ground combat division, an air wing, and a support group. The
active component of the Marine Corps has three MEFs, including
SPMAGTFs are task-organized to accomplish a specific
a total of three divisions, three air wings, and three logistics
mission, operation, or exercise and may be of any size, but
groups. The Marine Corps Reserve contains one division, one air
usually no larger than a MEU. They can conduct a variety
wing, and one support group, although they are not organized
of operations ranging from peacetime missions, training
into a fourth Marine expeditionary force. The MEFs, divisions, air
exercises, and responses to contingencies and crises,
wings, and logistics groups are not standardized units but instead
including disaster response and humanitarian assistance.
vary in size and composition.
Smaller, land-based SPMAGTFs—Crisis Response
(SPMAGTF-CR) units—are dedicated to geographic
The Marine Corps currently has 24 Active Component and 8
combatant commands and can conduct limited crisis
Reserve Component Infantry Battalions.
response, contingency, theater security cooperation, and
enabling operations.
How the Marine Corps Organizes Its
Operational Forces
Barbara Salazar Torreon, Senior Research Librarian
Andrew Feickert, Specialist in Military Ground Forces
Marine Air-Ground Task Force (MAGTF)
IF10571
The MAGTF is the Marine Corps’ principal organizational
construct for conducting missions across the range of
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Defense Primer: Organization of U.S. Ground Forces


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