Updated December 29, 2023
Defense Primer: Organization of U.S. Ground Forces
Overview
aviation brigade, an artillery brigade, an engineer brigade,
The Army is the U.S. military’s primary ground force. Title
and a logistics brigade. Army divisions consist of 12,000-
10, Subtitle B, Part I, Chapter 307 of the U.S. Code
16,000 personnel. Marine divisions, also commanded by
addresses the organization of the Army. The Marine Corps
major generals, consist of three regiments and supporting
serves as the Navy’s ground-focused fighting force. Title
units, and consist of about 6,600 personnel.
10, Subtitle C, Part I, Chapter 507, Section 5063 addresses
Marine Corps composition and functions.
Corps. Corps are commanded by a lieutenant general and
include two to five divisions and numerous support
Organizational Levels of U.S. Ground
brigades and commands. Corps have about 40,000-100,000
Forces
personnel. The Marines do not have designated corps,
The Congressional Budget Office’s (CBO’s), The U.S.
although a Marine Expeditionary Force (MEF) is similar in
Military’s Force Structure: A Primer, 2021 Update, notes:
size and also is commanded by a lieutenant general.
The Army and Marine Corps are generally
Army. An army is the highest command level in a given
organized as hierarchies of units, with each type of
theater of operations and typically has 100,000-300,000
unit commanded by a noncommissioned or
personnel. It is an element of a joint command structure,
commissioned officer of a specific rank. These units
with the Army’s component commanded by a general. An
are described from smallest to largest.
Army’s operational theater is established to support one or
Squad/Team/Section. A squad is led by a sergeant and
more corps and includes numerous support brigades and
consists of 4-12 personnel. Squads can be further divided
support commands.
into teams or sections.
Army Brigades
Platoon. A platoon—led (Army) or commanded (Marines)
According to the CBO’s U.S. Military’s Force Structure:
by a lieutenant and includes varying numbers of
Fiscal Year 2024 Update to Personnel Numbers and Costs,
subordinate squads, teams, or sections—may vary from 16
November 2023, and its Interactive Force Structure Tool,
to 50 personnel. Heavy platoons have armored vehicles,
Army brigades are organized as follows.
such as tanks or infantry fighting vehicles, depending on
platoon type.
The Brigade Combat Team (BCT) is the basic combined-
arms building block of the Army. It is a permanent, stand-alone,
Company/Troop/Battery. A company is commanded by a
self-sufficient, and standardized tactical force of about 4,000
captain and includes two to five subordinate platoons
soldiers. Accord to a 2023 CBO Interactive Force Structure
(usually three or four). It has about 60-200 personnel.
Tool, the Army presently has 59 BCTs, with 32 BCTs in the
Cavalry (air or ground) companies are called troops (Army
Regular Army (RA) and 27 BCTs in the Army National Guard
only); artillery and air and missile defense companies are
(ARNG).
called batteries.
The Army has three types of BCTs: Infantry BCTs (IBCTs),
Battalion/Squadron. A battalion is commanded by a
Armored BCTs (ABCTs), and Stryker BCTs (SBCTs).
lieutenant colonel and usually includes three to five combat
Infantry BCTs (IBCTs) include three infantry battalions, a
companies and a support company. It has about 400-1,000
reconnaissance and surveillance cavalry squadron, a field artil ery
personnel. Cavalry battalions are called squadrons.
battalion, a brigade engineer battalion, and a logistics support
battalion. IBCTs also are organized to be airborne or air-assault
Brigade Combat Team/Support
capable. The Army currently has 14 Active Component and 20
Brigades/Regiment/Group. Army brigades are
National Guard IBCTs.
commanded by a colonel and generally are configured as a
Armored BCTs (ABCTs) include three armor/mechanized
brigade combat team (BCT) or a support brigade. A BCT
infantry battalions, an armed reconnaissance cavalry squadron, a
has about 4,000-4,700 personnel, depending on type. Army
field artil ery battalion, a logistics support battalion, and a brigade
cavalry brigades are called regiments; some types of
engineer battalion. The Army currently has 11 Active
support brigades are called groups. Marine Corps units at
Component and 5 National Guard ABCTs.
this level also are called regiments. (The term Marine
Stryker BCTs (SBCTs) are equipped with the Stryker, an
Expeditionary Brigade [MEB] refers to a regimental-size
eight-wheel-drive armored vehicle. SBCTs consist of three
task force, which is larger than an Army Brigade Combat
infantry battalions, a cavalry squadron for reconnaissance and
Team [BCT]).
target acquisition, a field artil ery battalion, a brigade support
battalion, a brigade engineer battalion, a military intelligence
Division. An Army division is commanded by a major
company, an engineer company, a signal company, an antitank
general and includes two to five BCTs (usually four), an
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Defense Primer: Organization of U.S. Ground Forces
How the Marine Corps Organizes Its
company, and a headquarters company. The Army currently has
Operational Forces
7 Active Component and 2 National Guard SBCTs.
Functional Support Brigades
Marine Air-Ground Task Force
FSBs are designed to plug into operational formations at the
(MAGTF)
Army Service Component Command (ASCC), corps, division, or
The MAGTF is the Marine Corps’ principal organizational
theater level. Once deployed, these brigades conduct operational
construct for conducting missions across the range of
or theater-level support. There are several types of FSBs,
military operations. MAGTFs consist of command, ground
including air defense, artil ery, engineers, military police, cyber,
combat, air combat, and logistics elements.
signal, explosive ordinance disposal, medical support, and
aviation.
Types of MAGTFS
Multifunctional Support Brigades
There are three types of MAGTFs: the Marine
Expeditionary Force (MEF), the Marine Expeditionary
Similar to FSBs, MFSBs are designed to plug into operational
Brigade (MEB), and the Marine Expeditionary Unit
formations, but their purpose is to support BCTs. There are five
(MEU).
types of MFSBs: combat aviation, combat support, sustainment,
fires and battlefield surveil ance, and tactical-level task and
Marine Expeditionary Force (MEF)
support.
The MEF is the primary warfighting force for larger
Security Force Assistance Brigades (SFABs)
operations and consists of 46,000-90,000 Marines. There
SFABs are capable of conducting Security Force Assistance
are three active MEFs stationed in California, North
operations at a variety of levels. The Army has six regionally
Carolina, and Japan. Commanded by a Lieutenant General,
focused SFABs—five in the Active Component and one in the
MEFs are composed of a Marine Division, a Marine
Army National Guard (ARNG).
Aircraft Wing, and a Marine Logistics Group. MEFs are
For more information on SFABs, see CRS In Focus IF10675, Army
supplied for 60 days of operations.
Security Force Assistance Brigades (SFABs), by Andrew Feickert.
Marine Expeditionary Brigade (MEB)
Multi-Domain Task Force (MDTF)
MEBs are task organized for specific missions and consist
MDTFs are brigade-sized units capable of synchronizing precision
of 4,000-16,000 Marines. MEBs, commanded by a
effects and precision fires in all domains against adversary anti-
Brigadier General, have increased firepower and aviation
access/ area denial (A2/AD) networks. The Army plans to build
assets and are composed of a regimental-size Ground
five MDTFs.
Combat Element, an Aircraft Group, and a Combat
For more information on MDTFs, see CRS In Focus IF11797, The
Logistics Regiment. MEBs are supplied for 30 days of
Army’s Multi-Domain Task Force (MDTF), by Andrew Feickert.
operations.
Marine Expeditionary Unit (MEU)
Marine Corps
MEUs are forward deployed on Navy ships and are often
Adapted from the Marine, Air, Ground Task Force
first to arrive at a crisis. MEUs consist of 2,200 Marines
(MAGTF) and MAGTF Composition websites at (1)
and are commanded by a Colonel. MEUs are composed of a
https://www.marines.com/about-the-marine-corps/marine-
Battalion Landing Team; a Composite Helicopter
corps-structure/air-ground-task-force.html and (2)
Squadron; and a Combat Logistics Battalion. MEUs are
https://www.marines.mil/News/News-Display/Article/
supplied for 15 days of operations.
2708146/marine-littoral-regiment-mlr/.
Naval Formations
The Marine Corps is a hybrid service, with units that engage in
Marine Littoral Regiments
combat on the ground and in the air. The Marine Corps
MLRs are intended to operate and survive in a contested
organizes its forces into task forces, each with a command, ground
maritime environment where near-peer countries can
combat, aviation combat, and logistics combat element. The largest
challenge Marines for supremacy in the air or on sea. The
such task force, a Marine expeditionary force (MEF), includes a
MLRs are to be designed to control local air space, choke
ground combat division, an air wing, and a support group. The
points, or waterways. MLRs are to consist of about 1,800 to
active component of the Marine Corps has three MEFs, including
2,000 Marines and Sailors, and composed of three main
a total of three divisions, three air wings, and three logistics
elements: a Littoral Combat Team (LCT), a Littoral Anti-
groups. The Marine Corps Reserve contains one division, one air
Air Battalion, and a Combat Logistics Battalion.
wing, and one support group, although they are not organized
into a fourth Marine expeditionary force. The MEFs, divisions, air
For more information on MLRs, see CRS In Focus
wings, and logistics groups are not standardized units but instead
IF12200, The U.S. Marine Corps Marine Littoral Regiment
vary in size and composition.
(MLR), by Andrew Feickert.
According to CBO, the Marine Corps currently has 21 Active
Component and 8 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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https://crsreports.congress.gov | IF10571 · VERSION 8 · UPDATED

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