[sci.military] A Quick and Dirty Guide to US Unit Numbering

graham@cs.washington.edu (Stephen Graham) (03/07/91)

From: graham@cs.washington.edu (Stephen Graham)

A Quick and Dirty Guide to the Numbering of US Army Units
(and really brief comments on the Marines and Air Force)

Corps, Armies, and Army Groups

These units are raised and numbered in sequence as necessary. The 1st
through 5th Armies are administrative units within the Continental
US. Corps currently active are derived from WWII units, which were
numbered as they were raised. Army Groups are now multi-national
units (usually NATO) and are named.

Divisions

Divisions are numbered in sequence within the general divisions
Infantry, Armor, and Cavalry. The numbering sequence derives from
WWI and WWII. Regular Army (RA) divisions are numbered 1-25. National
Guard divisions fall within 26-50 and Divisions to be raised from
draftees are numbered 51 and above. In practice, Training Divisions
are numbered 70 and above, since the original pattern had WWI draftee
divisions numbered 76 and above. Very few National Guard divisions exist
any more. Recently active RA divisions include: 1st Mech, 2d Infantry,
3d Mech, 4th Mech, 5th Mech, 6th Light Infantry, 7th Light Infantry,
8th Mech, 9th Motorised, 10th Mountain, 24th Mech, 25th Light Infantry,
82d Airborne, 101st Air Assault, 1st Armored, 2d Armored, 3d Armored,
1st Cavalry (armored). The 82d and 101st started out as draftee divisions
in WWI, and were converted to RA when they became airborne in WWII

Brigades.

Brigades are stranger. If they are part of a division, they are numbered
as the 1st, 2d, 3d or 4th Brigade of the Xth Division. If independent,
Regular Army brigades are numbered 196-199 (a relic from Vietnam, hard to
say why). National Guard brigades derive their numbers from one of two
places: 1) The number of the WWII National Guard division they derive
from; or 2) The National Guard brigade in their area from before WWII.
(Prior to WWII, US Army Divisions had two brigades of two regiments each,
numbered in sequence according to divisional number: 1st Infantry Division
had 1st and 2d Infantry Brigades. The Washington National Guard contributed
the 81st Infantry Brigade to the 41st Division, it now provides the 81st
Infantry Brigade as a separate unit).

Regiments

Regiments are now administrative and honorary organizations. Prior to
the 1960's, they were the primary combat unit. They are numbered in sequence
in each branch (Infantry, Armor/Cavalry, Artillery, Engineer). The numbering
sequence is thus: 1-100 Regular Army and Reserves, 101-300 National Guard, 301-
draftees. Airborne units are numbered 501 and above. A couple of exceptions:
the 187th and 325th Infantry are RA Airborne units, but out of the normal
sequence. The 442d is a Reserve unit. I can explain this, but it'd take a
while. It makes sense if you know unit histories. Armor and Cavalry regiments
are numbered in sequence, as Armor was raised from Cavalry. However, it is
possible to have an Armor and a Cavalry regiment with the same number,
usually in the National Guard. It's just the way things are.

Smaller units (Battalions, Companies, whatever).

A mess. Theoretically, they follow the same numbering system as regiments,
but not really. Number sequences are unique within each branch, so that you
can have the 125th MP Company, 125th Intelligence Co, 125th Quartermaster
Co., etc. Sometimes it seems numbers are picked completely at random
for a unit.

Marines.

The Marines still have regiments as combat units. They, however, number
all regiments in sequence. So, the 1st Marines are infantry, but the 11th
Marines are artillery, etc. Their rational is that everyone's a Marine.

Air Force.

Air Force unit numbering is very odd. It's more or less random as far
as I can tell.

major@uunet.UU.NET (Mike Schmitt) (03/08/91)

From: bcstec!shuksan!major@uunet.UU.NET (Mike Schmitt)

> From: graham@cs.washington.edu (Stephen Graham)
> 
> A Quick and Dirty Guide to the Numbering of US Army Units
> (and really brief comments on the Marines and Air Force)

  Well done, well done.  (applause, applause).

> Brigades.................
> Regiments................

  Just an addendum to the difference between a Brigade and a Regiment.

  Basically, a Regiment can sustain itself on the battlefield and has
  organic combat arms, combat support, and combat service support units. 
  (ie the 3rd Armored Cavalry Regiment can operate independently and 
  requires no support from a higher organization.)

  A Brigade is a 'tactical command headquarters' - the division task 
  organization 'gives' the brigade commander x number of tank battalions,
  and x number of infantry battaions to fight with.  The brigade has no
  organic combat support nor combat service support units.  The division
  'slices' up his own support units and sends them to the brigade to form
  a brigade task force.   A Brigade cannot operate independently without
  support from its division.


  mike schmitt


       

millerjl@stolaf.edu (Jeffrey Miller) (03/13/91)

From: millerjl@stolaf.edu (Jeffrey Miller)
In article <1991Mar7.014546.2986@cbnews.att.com> graham@cs.washington.edu (Stephen Graham) writes:
>
>Very few National Guard divisions exist
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>any more.
 ^^^^^^^^


Excuse me, quite a few National Guard Divisions exist today.  The facts
I have are prior to troop reductions, but I have not heard of many full 
NG divisions being axed to warrent this statement (if any at all for
that matter.)  As of 1988 the NG divisions I know about are:

26th Infantry Division :elements in Massachusetts, Conniticut, and
	Rhode Island
28th Infantry Division :elements in Pennsylvania
29th Infantry Division :elements in Virginia and Maryland.
34th Infantry Division :(Until 10 FEB 91 this was the 47th INF DIV) elements
	in Minnesota, Iowa, Illinois, and a detachment in New Mexico
35th Infantry Division :elements in Kansas, Nebraska, Kentucky, Missouri,
	and Colorado.
38th Infantry Division :elements in Indiana and Michigan.
40th Infantry Division :elements in California and Nevada.
42nd Infantry Division :elements in the state of New York.
49th Armored Division :elements in the state of Texas.
50th Armored Division :elements in New Jersey.

These are just the divisions that I know of, and these are full 100% 
National Guard Divisions.  I do not have facts in front of me on how many
Regular Army divisions conatin National Guard augmentations, but I know
that there are some that do.  The latter category will increase as the
troop reductions start to occur on a wider scale.

In addition I know of at least 18 unattached NG Brigades, and 4
Armored Calvary Regiments that are NG:

	107th ACR: Ohio and West Virginia
	116th ACR: Idaho, Oregon, and Mississippi
	163rd ACD: Montana and Texas 
	278th ACR: Tennesse

Plus 16 Field Artillery Brigades, 4 Engineer Brigades, 3 Medical Brigades,
3 Military Police Brigades, 3 Signal Brigades, 2 Special Forces Groups,
a Transportation Brigade, the I Corps Artillery, and an Air Defense
Artillery Brigade.  All in all, the NG (and Army Reserve, but I do not
know as much about their units except that they only augment RA units and
divisions, support brigades, etc.) constitute 51% of the total United
States Army. (Percentage as of 1988, this will increase in the coming
years.)  So beware about making statements about how insignificant the
NG is in the total army.  Without us, the Regular Army is not a very
effective fighting force.

==============================================================================
"You killed my father. Prepare to die."  Inigo Montoya. _The Princess Bride_
"I choose the danger."  Bones. ST:TSFS
"I never lie when I have sand in my shoes."  LaForge.  ST:TNG

Jeffrey L. Miller  e-mail: millerjl@stolaf.edu

All opinions are my own and do not reflect the true nature of me.
==============================================================================

stuart@rennet.cs.wisc.edu (Stuart Friedberg) (03/13/91)

From: stuart@rennet.cs.wisc.edu (Stuart Friedberg)
In article <1991Mar7.014546.2986@cbnews.att.com> graham@cs.washington.edu (Stephen Graham) writes:
>Air Force unit numbering is very odd. It's more or less random as far
>as I can tell.

Well, that's a matter of perspective.  *Every* unit I can think of in
the Electronic Security Command has a number beginning 69, and the
numbers of smaller units are quite logically related to those of
larger ones.  E.g, 6940th ES Wing, 6941st through 6944th ES Squadron,
all belonging to the 6940 ESW.

Most, if not all AF training/school squadrons have numbers beginning
72 or 67.

Stu Friedberg (stuart@cs.wisc.edu, former member 6913 ESS & 6941 ESS)