AA (or AckAck) anti-aircraft guns

AP                   armor-piercing artillery shell

Arty                  artillery

AT                    anti-tank

Aussie              Australian

AWOL              absent without leave

BAR                 Browning automatic rifle

Bn                    battalion           (See US Army Chain of Command below)

Capt                 captain

Cn or CN           cannon

Co                    company          (See US Army Chain of Command below)

CO                   commanding officer

Col                   colonel

CP                    command post

Cpl or Cp          corporal

CWO                chemical warfare officer

DHQ                 division headquarters

Div                    division             (See US Army Chain of Command below)

DUKW              amphibious landing craft

FA                    field artillery

FO                    forward observer

GI                     soldier (literally, general issue)

GQ                   general quarters, all hands at battle stations

HE                    high explosive artillery shells

HMG                 heavy machine gun

Hq                    headquarters

I&R                  information and reconnaissance

Inf                    infantry

Jap                   Japanese

LCI                   landing craft infantry

LCM                 landing craft mechanized

LCS                  landing craft support

LCT                  landing craft tank

LCVP                landing craft vehicle personnel (Higgins boat)

LMG                 light machine gun

LSD                  landing ship dock

LST                  landing ship tank

Lt                     lieutenant

Lt Col               lieutenant colonel

LVT                  landing vehicle tracked (amphibious tanks)

M1 or M-1         rifle

Maj                   major

MG                   major general (or machine gun) depending on context

NCO                 non-commissioned officer

NG                   national guard (or New Guinea) depending on context

NICA                 Netherlands Indonesian Colonial Administration

Nip, Nipponese Japanese (Nippon is the Japanese term for Japan)

Noncom            non-commissioned officer

OP                   observation post

Ord                   ordnance

Pfc                   private first class

PIB                   Papuan Infantry Battalion

Pl or Pln           platoon             (See US Army Chain of Command below)

QM                   quartermaster

RCT                  regimental combat team

Recon               reconnaissance

RAAF               Royal Australian Air Force

Reg                  regiment           (See US Army Chain of Command below)

S/Sgt                staff sergeant

SBD                 Douglas aircraft dive-bomber

SWPA              Southwest Pacific Area

T/3                    technician, third class

T/4                    technician, fourth class

T/5                    technician, fifth class

T/Sgt                technical sergeant

TD                    tank destroyer

TDY                  temporary duty

Tommie (TSMG) Thompson sub-machine gun

Z-Day               D-Day (assault landing date)




The US Army is organized into Armies (3rd, 6th, 7th, etc.). Armies consist of subordinate units of Corps, Divisions, Regiments, Brigades, Battalions, Companies, Platoons and Squads.  The larger units are organized into Command structures consisting of Commander, Chief of Staff (XO) and Command Staff responsible for various functions.

The basic building block of all Army organizations is the individual soldier. A small group of soldiers organized to maneuver and fire is called a squad. As elements of the Army's organizational structure become larger units, they contain more and more subordinate elements from combat arms, combat support and combat service support units.

A company is typically the smallest Army element to be given a designation and affiliation with higher headquarters at battalion and brigade level. This alphanumeric and branch designation causes an "element" to become a "unit."

Squad - 9 to 10 soldiers. Typically commanded by a sergeant or staff sergeant, a squad or section is the smallest element in the Army structure, and its size is dependent on its function.

Platoon - 16 to 44 soldiers. A platoon is led by a lieutenant with an NCO as second in command, and consists of two to four squads or sections.

Company - 62 to 190 soldiers. Three to five platoons form a company, which is commanded by a captain with a first sergeant as the commander's principle NCO assistant. An artillery unit of equivalent size is called a battery, and a comparable armored or air cavalry unit is called a troop.

Battalion - 300 to 1,000 soldiers. Four to six companies make up a battalion, which is normally commanded by a lieutenant colonel with a command sergeant major as principle NCO assistant. A battalion is capable of independent operations of limited duration and scope. An armored or air cavalry unit of equivalent size is called a squadron.

Brigade - 3,000 to 5,000 solders. A brigade headquarters commands the tactical operation of two to five organic or attached combat battalions. Normally commanded by a colonel with a command sergeant major as senior NCO, brigades are employed on independent or semi-independent operations. Armored cavalry, ranger and special forces units this size are categorized as regiments or groups.

Division - 10,000 to 15,000 soldiers. Usually consisting of three brigade-sized elements and commanded by a major general, divisions are numbered and assigned missions based on their structures. The division performs major tactical operations for the corps and can conduct sustained battles and engagements.

Corps - 20,000 to 45,000 soldiers. Two to five divisions constitute a corps, which is typically commanded by a lieutenant general. As the deployable level of command required to synchronize and sustain combat operations, the corps provides the framework for multi-national operations.

Army - 50,000 + soldiers. Typically commanded by a lieutenant general or higher, an army combines two or more corps. A theater army is the ranking Army component in a unified command, and it has operational and support responsibilities that are assigned by the theater commander in chief. The commander in chief and theater army commander may order formation of a field army to direct operations of assigned corps and divisions. An army group plans and directs campaigns in a theater, and is composed of two or more field armies under a designated commander. The Army has not employed army groups since World War II.

Command Staff Designations: 1-Personnel, 2-Intelligence, 3-Operations, 4-Logistics, 5-Civil/Military Operations, 6-Signals (communications, etc.) "G" designations identify the officer (and corresponding staff) is at the Corps or Division level. "S" designations indicate Regiment, Brigade or Battalion level function.  Therefore An S2 would be the staff officer responsible for all intelligence activities in either a Regiment, Brigade or Battalion unit.  His counterpart at Division or Corps would be designated G4.

Above Information Derived from DA Pamphlet 10-1