Defense Primer: Organization of U.S. Ground Forces

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Updated October 10, 2024

Defense Primer: Organization of U.S. Ground Forces

Overview

The Army is the U.S. military’s primary ground force. Title 10, Subtitle B, Part I, Chapter 307 of the U.S. Code addresses the organization of the Army. The Marine Corps serves as the Navy’s ground-focused fighting force. Title 10, Subtitle C, Part I, Chapter 507, Section 5063 addresses Marine Corps composition and functions.

Organizational Levels of U.S. Ground Forces

The Congressional Budget Office’s (CBO’s), The U.S. Military’s Force Structure: A Primer, 2021 Update, notes

The Army and Marine Corps are generally organized as hierarchies of units, with each type of unit commanded by a noncommissioned or commissioned officer of a specific rank. These units are described from smallest to largest.

Squad/Team/Section. A squad is led by a sergeant and consists of 4-12 personnel. Squads can be further divided into teams or sections.

Platoon. A platoon—led (Army) or commanded (Marines) by a lieutenant and includes varying numbers of subordinate squads, teams, or sections—may vary from 16 to 50 personnel. Heavy platoons have armored vehicles, such as tanks or infantry fighting vehicles, depending on platoon type.

Company/Troop/Battery. A company is commanded by a captain and includes two to five subordinate platoons (usually three or four). It has about 60-200 personnel. Cavalry (air or ground) companies are called troops (Army only); artillery and air and missile defense companies are called batteries.

Battalion/Squadron. A battalion is commanded by a lieutenant colonel and usually includes three to five combat companies and a support company. It has about 400-1,000 personnel. Cavalry battalions are called squadrons.

Brigade Combat Team/Support Brigades/Regiment/Group. Army brigades are commanded by a colonel and generally are configured as a brigade combat team (BCT) or a support brigade. A BCT has about 4,000-4,700 personnel, depending on type. Army cavalry brigades are called regiments; some types of support brigades are called groups. Marine Corps units at this level also are called regiments. (The term Marine Expeditionary Brigade [MEB] refers to a regimental-size task force, which is larger than an Army Brigade Combat Team [BCT]).

Division. An Army division is commanded by a major general and includes two to five BCTs (usually four), an

aviation brigade, an artillery brigade, an engineer brigade, and a logistics brigade. Army divisions consist of 12,000- 16,000 personnel. Marine divisions, also commanded by major generals. Each division has three infantry regiments and one artillery regiment and consists of about 20,000 personnel.

Corps. Corps are commanded by a lieutenant general and include two to five divisions and numerous support brigades and commands. Army corps have about 40,000- 100,000 personnel. The Marines do not have designated corps, although a Marine Expeditionary Force (MEF) is similar in size and also is commanded by a lieutenant general.

Army. An army is the highest command level in a given theater of operations and typically has 100,000-300,000 personnel. It is an element of a joint command structure, with the Army’s component commanded by a general. An Army’s operational theater is established to support one or more corps and includes numerous support brigades and support commands.

Army Brigades

According to the CBO’s The U.S. Military’s Force Structure: Fiscal Year 2024 Update to Personnel Numbers and Costs, and its Interactive Force Structure Tool (November 2023), Army brigades are organized as follows.

The Brigade Combat Team (BCT) is the basic combined- arms building block of the Army. It is a permanent, stand-alone, self-sufficient, and standardized tactical force of about 4,000 soldiers. The Army presently has 59 BCTs, with 32 BCTs in the Regular Army (RA) and 27 BCTs in the Army National Guard (ARNG). The Army has three types of BCTs: Infantry BCTs (IBCTs), Armored BCTs (ABCTs), and Stryker BCTs (SBCTs). Infantry BCTs (IBCTs) include three infantry battalions, a reconnaissance and surveillance cavalry squadron, a field artillery battalion, a brigade engineer battalion, and a logistics support battalion. IBCTs also are organized to be airborne or air-assault capable. The Army currently has 14 Active Component and 20 National Guard IBCTs. 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 engineer battalion. The Army currently has 11 Active Component and 5 National Guard ABCTs. Stryker BCTs (SBCTs) are equipped with the Stryker, an eight-wheel-drive armored vehicle. SBCTs consist of three infantry battalions, a cavalry squadron for reconnaissance and target acquisition, a field artillery battalion, a brigade support battalion, a brigade engineer battalion, a military intelligence company, an engineer company, a signal company, an antitank

Defense Primer: Organization of U.S. Ground Forces

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company, and a headquarters company. The Army currently has 7 Active Component and 2 National Guard SBCTs. Functional Support Brigades FSBs are designed to plug into operational formations at the Army Service Component Command (ASCC), corps, division, or theater level. Once deployed, these brigades conduct operational or theater-level support. There are several types of FSBs, including air defense, artillery, engineers, military police, cyber, signal, explosive ordinance disposal, medical support, and aviation. Multifunctional Support Brigades Similar to FSBs, MFSBs are designed to plug into operational formations, but their purpose is to support BCTs. There are five types of MFSBs: combat aviation, combat support, sustainment, fires and battlefield surveillance, and tactical-level task and support. Security Force Assistance Brigades (SFABs) SFABs are capable of conducting Security Force Assistance operations at a variety of levels. The Army has six regionally focused SFABs—five in the Active Component and one in the Army National Guard (ARNG). Multi-Domain Task Force (MDTF) MDTFs are brigade-sized units capable of synchronizing precision effects and precision fires in all domains against adversary anti- access/ area denial (A2/AD) networks. The Army plans to build five MDTFs.

Marine Corps

The Marine Corps is a hybrid service, with units that engage in combat on the ground and in the air. The Marine Corps organizes its forces into task forces, each with a command, ground combat, aviation combat, and logistics combat element. The largest such task force, a Marine expeditionary force (MEF), includes a ground combat division, an air wing, and a support group. The active component of the Marine Corps has three MEFs, including a total of three divisions, three air wings, and three logistics groups. The Marine Corps Reserve contains one division, one air wing, and one support group, although they are not organized into a fourth Marine expeditionary force.

According to CBO, the Marine Corps currently has 21 Active Component and eight Reserve Component Infantry Battalions.

How the Marine Corps Organizes Its Operational Forces

The Marines organize operational forces as follows:

Marine Air-Ground Task Force (MAGTF)

The MAGTF is the Marine Corps’ principal organizational construct for conducting missions across the range of military operations. MAGTFs consist of ground, air, logistics, and cyberspace assets under a under a central command.

Types of MAGTFS There are three types of MAGTFs: the Marine Expeditionary Force (MEF), the Marine Expeditionary Brigade (MEB), and the Marine Expeditionary Unit (MEU).

Marine Expeditionary Force (MEF) The MEF is the primary warfighting force for larger operations and consists of 46,000-90,000 Marines. There are three active MEFs stationed in California, North Carolina, and Japan. Commanded by a Lieutenant General, MEFs are composed of a Marine Division, a Marine Aircraft Wing, and a Marine Logistics Group. MEFs are supplied for 60 days of operations.

Marine Expeditionary Brigade (MEB) MEBs are task organized for specific missions and consist of 4,000-16,000 Marines. MEBs, commanded by a Brigadier General, have increased firepower and aviation assets and are composed of a regimental-size Ground Combat Element, an Aircraft Group, and a Combat Logistics Regiment. MEBs are supplied for 30 days of operations.

Marine Expeditionary Unit (MEU) MEUs are forward deployed on Navy ships and are often first to arrive at a crisis. Described as “extremely versatile, quick to respond,” MEUs consist of 2,200 Marines and are commanded by a Colonel. MEUs are composed of a Battalion Landing Team; a Composite Helicopter Squadron; and a Combat Logistics Battalion. MEUs are supplied for 15 days of operations.

Naval Formations

Marine Littoral Regiments MLRs are intended to operate and survive in a contested maritime environment where near-peer countries can challenge Marines for supremacy in the air or on sea. The MLRs are to be designed to control local air space, choke points, or waterways. MLRs are to consist of about 1,800 to 2,000 Marines and Sailors, and composed of three main elements: a Littoral Combat Team (LCT), a Littoral Anti- Air Battalion, and a Combat Logistics Battalion.

Related CRS Products

CRS In Focus IF10675, Army Security Force Assistance Brigades (SFABs), by Andrew Feickert.

CRS In Focus IF11409, Defense Primer: Army Multi- Domain Operations (MDO), by Andrew Feickert.

CRS In Focus IF11797, The Army’s Multi-Domain Task Force (MDTF), by Andrew Feickert.

CRS In Focus IF12200, The U.S. Marine Corps Marine Littoral Regiment (MLR), by Andrew Feickert.

Barbara Salazar Torreon, Senior Research Librarian Andrew Feickert, Specialist in Military Ground Forces

IF10571

Defense Primer: Organization of U.S. Ground Forces

https://crsreports.congress.gov | IF10571 · VERSION 10 · UPDATED

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