Updated November 16, 2018
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:
Platoon: A platoon—which is led (Army) or commanded
(Marines) by a lieutenant and includes varying numbers of
subordinate squads, teams, or sections—may vary from 16
The Brigade Combat Team (BCT) is the basic combined-arms
to 50 personnel. Heavy platoons also have armored vehicles
building block of the Army. It is a permanent, stand-alone, self-
(such as tanks or infantry fighting vehicles, depending on
sufficient, and standardized tactical force of about 4,000 soldiers.
the type of platoon).
At present, the Army is realigning BCTs to better address the
threat of near-peer competitors and this realignment is planned
Company/Troop/Battery: A company is commanded by a
to be completed by FY2020.
captain and includes two to five subordinate platoons
The Army has three types of BCTs: Infantry BCTs (IBCTs),
(usually three or four). It has about 100-200 personnel.
Armored BCTs (ABCTs), and Stryker BCTs (SBCTs).
Cavalry (air or ground reconnaissance units) companies are
Infantry BCTs (IBCTs) include three infantry battalions, a
called troops (Army only); artillery and air and missile
reconnaissance and surveillance cavalry squadron, a field artillery
defense companies are called batteries.
battalion, a brigade engineer battalion, and a logistics support
battalion. IBCTs also are organized to be airborne or air-assault
Battalion/Squadron: A battalion is commanded by a
capable. By FY2020, the Army plans to have 13 Active
lieutenant colonel and usually includes three to five combat
Component and 20 National Guard IBCTs.
companies and one support company. It has about 500 to
900 personnel. Cavalry battalions are called squadrons.
Armored BCTs (ABCTs) include three armor/mechanized
infantry battalions, an armed reconnaissance cavalry squadron, a
field artillery battalion, a logistics support battalion, and a brigade
Brigade Combat Team/Support
engineer battalion. By FY2020, the Army plans to have 11 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), a functional support brigade
Stryker BCTs (SBCTs) are centered on the Stryker, an eight-
(FSB), or a multifunctional support brigade (MFSB). Each
wheel-drive armored vehicle. SBCTs consist of three infantry
brigade has about 3,900-4,100 personnel. Army cavalry
battalions, a cavalry squadron for reconnaissance and target
brigades are called regiments; some types of support
acquisition, a field artillery battalion, a brigade support battalion,
brigades are called groups. Marine Corps units at this level
a brigade engineer battalion, a military intelligence company, an
also are called regiments. (The term Marine expeditionary
engineer company, a signal company, an antitank company, and a
brigade [MEB] refers to a regimental-size task force, which
headquarters company. By FY2020, the Army plans to have 7
is larger than a standard Army brigade).
Active Component and 2 National Guard SBCTs.
Functional Support Brigades
Division: An Army division is commanded by a major
FSBs are designed to plug into operational formations at the
general and includes two to five BCTs (usually four), an
Army Service Component Command (ASCC), corps, division, or
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
theater level. Once deployed, these brigades conduct operational
Operational Forces
or theater-level support. There are several types of FSBs,
including air defense, artillery, engineers, military police, cyber,
Marine Air-Ground Task Force (MAGTF)
signal, explosive ordinance disposal, medical support, and
The MAGTF is the Marine Corps’ principal organizational
aviation.
construct for conducting missions across the range of
Multifunctional Support Brigades
military operations. MAGTFs consist of command, ground
Similar to FSBs, MFSBs are designed to plug into operational
combat, air combat, and support elements.
formations, but their purpose is to support BCTs. There are five
types of MFSBs: combat aviation, combat support, sustainment,
Ground Combat Element (GCE)
fires and battlefield surveillance, and tactical-level task and
The GCE conducts land-based and amphibious operations,
support.
including offensive, defensive, humanitarian,
reconnaissance, and security operations. Unlike Army
Security Force Assistance Brigades (SFABs)
BCTs, Marine infantry battalions are light-infantry
(For more information on SFABs, see CRS In Focus IF10675,
organizations and are not intended to operate
Army Security Force Assistance Brigades (SFABs), by Andrew
independently. Typical operations include amphibious
Feickert.)
assault and raid, reconnaissance and surveillance, hostage
SFABs are capable of conducting Security Force Assistance at the
recovery, disaster relief, and non-combatant evacuation
tactical (brigade and below) level. In May 2018, the Army
operations.
announced it would establish six SFABs—five in the Active
Component and one in the Army National Guard (ARNG). To
Marine Corps Combat Organizations
date, the Army has activated two Active Component SFABs and
There are four types of MAGTFs: the MEF; the MEB; the
is in beginning stages of activating the ARNG SFAB. SFABs
Marine Expeditionary Unit (MEU); and the Special Purpose
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 fully operational
Marine Expeditionary Force
ABCTs or IBCTs capable of conducting major combat
MEFs are the primary warfighting force for larger
operations. In this case, SFAB personnel would serve as cadres
operations. Consisting of 46,000-90,000 Marines and
who would accept the expansion of personnel and equipment
sailors and commanded by a lieutenant general, MEFs are
required to transform the SFAB into either an ABCT or IBCT.
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 2016, pp. 45-46;
4,000-16,000 Marines and sailors, and are commanded by a
and The U.S. Military’s Force Structure: Fiscal Year 2019
brigadier general. MEBs have a regimental-size ground
Update to Personnel Numbers and Costs, August 15, 2018,
combat element and are embarked aboard amphibious
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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