Updated January 2, 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 Components.
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-arms
(such as tanks or infantry fighting vehicles, depending on
building block of the Army. It is a permanent, stand-alone, self-
the type of platoon).
sufficient, and standardized tactical force of about 4,000 soldiers.
At present, the Army consists of 58 BCTs, with 31 BCTs in the
Company/Troop/Battery: A company is commanded by a
Regular Army (RA) and 27 BCTs in the Army National Guard
captain and includes two to five subordinate platoons
(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 2020, the Army wil have 13 Active Component
companies and one support company. It has about 500 to
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 2020, the Army wil have 11 Active
commanded by a colonel and generally are configured as a
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 2020, the Army wil have 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 four), an
aviation brigade, an artillery brigade, an engineer brigade,
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Defense Primer: Organization of U.S. Ground Forces
How the Marine Corps Organizes Its
FSBs are designed to plug into operational formations at the
Operational Forces
Army Service Component Command (ASCC), corps, division, or
theater level. Once deployed, these brigades conduct operational
Marine Air-Ground Task Force (MAGTF)
or theater-level support. There are several types of FSBs,
The MAGTF is the Marine Corps’ principal organizational
including air defense, artil ery, engineers, military police, cyber,
construct for conducting missions across the range of
signal, explosive ordinance disposal, medical support, and
military operations. MAGTFs consist of command, ground
aviation.
combat, air combat, and support elements.
Multifunctional Support Brigades
Similar to FSBs, MFSBs are designed to plug into operational
Ground Combat Element (GCE)
formations, but their purpose is to support BCTs. There are five
The GCE conducts land-based and amphibious operations,
types of MFSBs: combat aviation, combat support, sustainment,
including offensive, defensive, humanitarian,
fires and battlefield surveil ance, and tactical-level task and
reconnaissance, and security operations. Unlike Army
support.
BCTs, Marine infantry battalions are light-infantry
organizations and are not intended to operate
Security Force Assistance Brigades (SFABs)
independently. Typical operations include amphibious
(For more information on SFABs, see CRS In Focus IF10675,
assault and raid, reconnaissance and surveillance, hostage
Army Security Force Assistance Brigades (SFABs), by Andrew
recovery, disaster relief, and non-combatant evacuation
Feickert.)
operations.
SFABs are capable of conducting Security Force Assistance at the
tactical (brigade and below) level. In May 2018, the Army
Marine Corps Combat Organizations
announced it would establish six SFABs—five in the Active
There are four types of MAGTFs: the MEF; the MEB; the
Component and one in the Army National Guard (ARNG).
Marine Expeditionary Unit (MEU); and the Special Purpose
SFABs consist of about 500 soldiers, with most being officers and
MAGTF (SPMAGTF).
noncommissioned officers (NCOs). The Army also plans for
SFABs to be expanded, if the need arises, into ful y operational
Marine Expeditionary Force
BCTs capable of conducting major combat operations. In this
MEFs are the primary warfighting force for larger
case, SFAB personnel would serve as cadres who would accept
operations. Consisting of 46,000-90,000 Marines and
the expansion of personnel and equipment required to transform
sailors and commanded by a lieutenant general, MEFs are
the SFAB into a BCT.
composed of a Marine division, aircraft wing, and logistics
group.
Marine Corps
Marine Expeditionary Brigade
Adapted from the Congressional Budget Office’s The U.S.
MEBs are task-organized for specific missions, consist of
Military’s Force Structure: A Primer, July 29, 2016, pp.
4,000-16,000 Marines and sailors, and are commanded by a
45-46; and The U.S. Military’s Force Structure: Fiscal Year
brigadier general. MEBs have a regimental-size ground
2019 Update to Personnel Numbers and Costs, August 15,
combat element and are embarked aboard amphibious
2018, at https://www.cbo.gov/publication/54136.
assault ships.
Marine Expeditionary Unit
The Marine Corps is a hybrid service, with units that engage in
combat on the ground and in the air. The Marine Corps
MEUs consist of 2,200 Marines and sailors and are a
organizes its forces into task forces, each with a command, ground
forward-deployed crisis-response force. MEUs deploy as
combat, air combat, and support element. The largest such task
part of an amphibious ready group (ARG) and are
force, a Marine expeditionary force (MEF), includes a ground
commanded by a colonel.
combat division, an air wing, and a support group. The active
Special Purpose MAGTF
component of the Marine Corps has three MEFs, including a total
of three divisions, three air wings, and three logistics groups. The
SPMAGTFs are task-organized to accomplish a specific
Marine Corps Reserve contains one division, one air wing, and
mission, operation, or exercise. They can conduct a variety
one support group, although they are not organized into a fourth
of operations ranging from peacetime missions, training
Marine expeditionary force. The MEFs, divisions, air wings, and
exercises, and responses to contingencies and crises,
logistics groups are not standardized units but instead vary in size
including disaster response and humanitarian assistance.
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.
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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