I have been asked many times about our Army infantry structure in Vietnam.  Sometimes it appeared confusing so I am going to try to straighten it out.

Our unit was Charlie Company, 1st Battalion, 22nd Infantry Regiment, 4th Infantry Division or C/1/22/4th Inf.

Fireteam A fireteam is a small military unit of infantry. It is the second smallest unit in the militaries that use it (smallest are support teams such as machine gun teams, mortar teams, sniper teams, or military working dog teams) and is the primary unit upon which infantry organization is. Fireteams generally consist of four or fewer soldiers and are usually grouped by two or three teams into a squad. Squad In the United States Army, a squad is composed of two fireteams of four soldiers each, as well as a squad leader who is a Staff Sergeant.

Platoon

A platoon is a military unit typically composed of two to four squads.  In US military organization, the platoon can be from as few as nine (e.g., Communications Platoon, Headquarters and Headquarters Company [HHC], Infantry [Airborne, Air Assault, Light] Battalion) to over 100 members (e.g., Maintenance Platoon, HHC, Infantry [Mechanized] Battalion]. Platoons are normally organized into a company, which typically consists of three, four or five platoons. A platoon is typically the smallest/lowest echelon military unit led by a commissioned officer—the platoon leader usually a lieutenant.

Company

A company is a military unit, typically consisting of 80–250 soldiers and usually commanded by a captain. Most companies are formed of three to six platoons although the exact number may vary by country, unit type, and structure. Several companies are grouped to form a battalion or regiment, the latter of which is sometimes formed by several battalions. In the United States Army, infantry companies are usually made up of three rifle platoons and a heavy weapons platoon; mechanized infantry companies are usually made up of three rifle platoons and a command element; tank companies are usually made up of three tank platoons and a command element; support companies are typically divided into platoons of specialization that may contain additional special sections. A company is usually commanded by an Army captain, although in rare cases they may be commanded by a 1st lieutenant or a major. Unlike its components, platoons, a company typically has additional positions of supporting staff such as an executive officer (XO), a readiness/training NCO, and other positions (e.g. supply sergeant). By tradition, the corresponding unit of artillery is always called a “battery”. Similarly, the term “troop” is used for cavalry units, including both the horse-mounted units of history as well as modern armored cavalry and air cavalry units. Companies which are not separate from their parent battalion are identified by letter—for example, “C Company, 1st Battalion, 22nd Infantry Regiment.” This would commonly be abbreviated as “C/1/22 INF” in writing, but not in speaking. When the regimental headquarters exists as a separate echelon of command (e.g., the 75th Ranger Regiment, the 11th Armored Cavalry Regiment, and the 1st Marine Regiment), as virtually all US Army regiments did until after the Korean War, a slash separates the battalion/squadron number from the regimental number (i.e., B/2/75 Ranger, C/3/11 ACR, E/2/1 Marines). The letters are usually pronounced using the NATO phonetic alphabet or, before that, the Joint Army/Navy Phonetic Alphabet, resulting in names such as “Bravo Company” and “Echo Company” (formerly “Baker” and “Easy” Companies, respectively). Companies with a separate Table of Organization and Equipment are identified by a number, and are able to operate completely independently from any other unit’s support.

Battalion

A battalion is a military unit with 300 to 1,200 soldiers that usually consists of two to seven companies and is commanded by either a lieutenant colonel or a colonel, if in the United States Army. Several battalions form a regiment or brigade. A battalion is generally the smallest military organization capable of independent operations (although it must have a source of re-supply to sustain operations for more than several days) because, in addition to comprising sufficient personnel and equipment (usually at least two primary mission companies and one mission support company) to perform significant operations, as well as a limited self-contained administrative and logistics capability, the commander is provided with a full-time staff whose function is to coordinate current operations and plan future operations. A battalion’s subordinate units (companies and their organic platoons) are dependent upon the battalion headquarters for command, control, communications, and intelligence and the battalion’s organic service and support structure to perform their mission. The battalion is usually part of a regiment, brigade, or group, depending on the organizational model used by that service.

Historical Organization

The United States Army was also once organized into regiments, but in the 20th century the division became the tactical and administrative unit. Industrial management techniques were used to draft, assemble, equip, train and then employ huge masses of conscripted civilians in very short order, starting with minimal resources. Historically, a regiment consisted of three battalions and the regiment headquarters (HQ) company. Training, administration and even tactical employment were centered at divisional level. Many, but not all combat support and logistics was also concentrated at that level. A new system, the Combat Arms Regimental System, or CARS, was adopted in 1957 to replace the old regimental system. CARS uses the Army’s traditional regiments as parent organizations for historical purposes, but the primary building blocks are divisions, brigades, and battalions. Each battalion carries an association with a parent regiment, even though the regimental organization no longer exists. In some brigades several numbered battalions carrying the same regimental association may still serve together, and tend to consider themselves part of the traditional regiment when in fact they are independent battalions serving a brigade, rather than a regimental, headquarters. The CARS was replaced by the United States Army Regimental System (USARS) in 1981.