Updated November 22, 2021
Defense Primer: Organization of U.S. Ground Forces
Overview
Division. An Army division is commanded by a major
The Army is the U.S. military’s primary ground force. Title
general and includes two to five BCTs (usually four), an
10, Subtitle B, Part I, Chapter 307 of the U.S. Code
aviation brigade, an artillery brigade, an engineer brigade,
addresses the organization of the Army. The Marine Corps
and a logistics brigade. Army divisions consist of 12,000-
serves as the Navy’s land-based fighting force. Title 10,
16,000 personnel.
Subtitle C, Part I, Chapter 507, Section 5063 addresses
Marine Corps composition and functions. For the National
Corps. Corps are commanded by a lieutenant general and
Guard and Reserves, see CRS In Focus IF10540, Defense
include two to five divisions and numerous support
Primer: Reserve Forces.
brigades and commands. Corps have about 40,000-100,000
personnel. The Marines do not have designated corps,
Organizational Levels of U.S. Ground
although a Marine Expeditionary Force (MEF) is similar in
Forces
size and also is commanded by a lieutenant general.
The Congressional Budget Office’s (CBO’s) The U.S.
Military’s Force Structure: A Primer, 2021 Update notes:
Army. An army is the highest command level in a given
theater of operations and typically has 100,000-300,000
The Army and Marine Corps are generally organized as
personnel. It is an element of a joint command structure,
hierarchies of 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 U.S. Military’s Force Structure: A
Primer, 2021 Update, Army Brigades are organized as
Platoon. A platoon—led (Army) or commanded (Marines)
follows.
by a lieutenant and includes varying numbers of
subordinate squads, teams, or sections—may vary from 16
to 50 personnel. Heavy platoons have four 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 60 BCTs, with 32
Company/Troop/Battery. A company is commanded by a
BCTs in the Regular Army (RA) and 28 BCTs in the Army
captain and includes two to five subordinate platoons
National Guard (ARNG).
(usually three or four). It has about 60-200 personnel.
The Army has three types of BCTs: Infantry BCTs (IBCTs),
Heavy companies have 14 armored vehicles. Cavalry (air or
Armored BCTs (ABCTs), and Stryker BCTs (SBCTs).
ground) companies are called troops (Army only); artillery
Infantry BCTs (IBCTs) include three infantry battalions, a
and air and missile 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. The Army currently has 13 Active Component and 21
companies and one support company. It has about 400-
National Guard IBCTs.
1,000 personnel. Heavy battalions have 58 armored
Armored BCTs (ABCTs)
vehicles. Cavalry battalions are called squadrons.
include three armor/mechanized
infantry battalions, an armed reconnaissance cavalry squadron, a
field artil ery battalion, a logistics support battalion, and a brigade
Brigade Combat Team/Support
engineer battalion. The Army currently has 12 Active
Brigades/Regiment/Group. Army brigades are
Component and 5 National Guard ABCTs.
commanded by a colonel and generally are configured as a
brigade combat team (BCT) or a support brigade. A BCT
Stryker BCTs (SBCTs) are centered on the Stryker, an eight-
has about 4,000-4,700 personnel, depending on type. Army
wheel-drive armored vehicle. SBCTs consist of three infantry
cavalry brigades are called regiments; some types of
battalions, a cavalry squadron for reconnaissance and target
support brigades are called groups. Marine Corps units at
acquisition, a field artil ery battalion, a brigade support battalion,
this level also are called regiments. (The term Marine
a brigade engineer battalion, a military intelligence company, an
Expeditionary Brigade [MEB] refers to a regimental-size
engineer company, a signal company, an antitank company, and a
task force, which is larger than a BCT).
headquarters company. The Army currently has 7 Active
Component and 2 National Guard SBCTs.
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Defense Primer: Organization of U.S. Ground Forces
How the Marine Corps Organizes Its
Functional Support Brigades
Operational Forces
FSBs are designed to plug into operational formations at the
Army Service Component Command (ASCC), corps, division, or
Marine Air-Ground Task Force (MAGTF)
theater level. Once deployed, these brigades conduct operational
The MAGTF is the Marine Corps’ principal organizational
or theater-level support. There are several types of FSBs,
construct for conducting missions across the range of
including air defense, artil ery, engineers, military police, cyber,
military operations. MAGTFs consist of command, ground
signal, explosive ordinance disposal, medical support, and
combat, air combat, and logistics elements.
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
SFABs are capable of conducting Security Force Assistance
MEFs are the primary warfighting force for larger
operations at a variety of levels. The Army has six regionally
operations. Consisting of 46,000-90,000 Marines and
focused SFABs—five in the Active Component and one in the
Sailors and commanded by a lieutenant general, MEFs are
Army National Guard (ARNG).
composed of a Marine division, aircraft wing, and logistics
(For more information on SFABs, see CRS In Focus IF10675,
group.
Army Security Force Assistance Brigades (SFABs), by Andrew
Feickert.)
Marine Expeditionary Brigade
Multi-Domain Task Force (MDTF)
MEBs are task-organized for specific missions, and consist
of a force of 4,000-16,000 Marines and Sailors, and are
MDTFs are brigade-sized units capable of synchronizing precision
commanded by a brigadier general. MEBs have a
effects and precision fires in all domains against adversary anti-
regimental-size ground combat element and are embarked
access/ area denial (A2/AD) networks. The Army plans to build
aboard amphibious assault ships.
five MDTFs: two aligned to the Indo-Pacific region; one aligned to
Europe; one stationed in the Arctic region and oriented on
Marine Littoral Regiments
multiple threats; and a fifth MDTF aligned for global response.
MLRs are intended to operate and survive in a contested
(For more information on MDTFs, see CRS In Focus IF11797,
maritime environment where near-peer countries can
The Army’s Multi-Domain Task Force (MDTF), by Andrew Feickert.)
challenge Marines for supremacy in the air or on sea. The
MLR are to be designed to control local air space, choke
Marine Corps
points or waterways. MLRs are to consist of about 1,800 to
2,000 Marines and Sailors, and comprised of three main
Adapted from the Marine, Air, Ground Task Force
elements: a Littoral Combat Team (LCT), a Littoral Anti-
(MAGTF) and MAGTF Composition websites at
Air Battalion, and a Littoral Logistics Battalion.
https://www.marines.com/about-the-marine-corps/marine-
corps-structure/air-ground-task-force.html; and
Marine Expeditionary Unit
https://www.26thmeu.marines.mil/About/MAGTF/.
MEUs consist of approximately 2,200 Marines and Sailors
and are a forward-deployed crisis-response force. MEUs
deploy as part of an amphibious ready group (ARG) and are
The Marine Corps is a hybrid service, with units that engage in
commanded by a colonel.
combat on the ground and in the air. The Marine Corps
organizes its forces into task forces, each with a command, ground
Special Purpose MAGTF
combat, aviation combat, and logistics combat element. The largest
SPMAGTFs are task-organized to accomplish a specific
such task force, a Marine expeditionary force (MEF), includes a
mission, operation, or exercise and may be of any size, but
ground combat division, an air wing, and a support group. The
usually no larger than a MEU. They can conduct a variety
active component of the Marine Corps has three MEFs, including
of operations ranging from peacetime missions, training
a total of three divisions, three air wings, and three logistics
exercises, and responses to contingencies and crises,
groups. The Marine Corps Reserve contains one division, one air
including disaster response and humanitarian assistance.
wing, and one support group, although they are not organized
Smaller, land-based SPMAGTFs—Crisis Response-Central
into a fourth Marine expeditionary force. The MEFs, divisions, air
Command (SPMAGTF-CR-CC) units—that were dedicated
wings, and logistics groups are not standardized units but instead
to geographic combatant commands and conducted limited
vary in size and composition.
crisis response were utilized until the Marine Corps ended
The Marine Corps currently has 24 Active Component and 8
their rotations in October 2021.
Reserve Component Infantry Battalions.
Barbara Salazar Torreon, Senior Research Librarian
Andrew Feickert, Specialist in Military Ground Forces
IF10571
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Defense Primer: Organization of U.S. Ground Forces


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