Military Unit Nomenclature/Numbering Systems

[BakerMikeRomeo]

Hi, everybody,


My question is sort of simple, but I think it'll have a lengthy answer. Unfortunately, I just don't know what to look for, or I expect I could find the answer straight away on google or wikipedia, so here goes:

How are the various units in our military (and others, if'n y'all know) assigned their numbers and what do they mean, if anything?

Like, why is the 101st Airborne Division the 101? The 173rd Airborne Brigade its number?

I sometimes see a unit's regular number followed by a fraction like "3/4 USMC" or something like that.

I can't think of anymore examples just now, but I hope y'all get the idea and can help me out.

Thanks in advance,
~GnSx

...
'Cause I'm [SPARE]Gunny, yes, I'm the real Gunny, all you other [SPARE]Gunnies are just imitating, so won't the real [SPARE]Gunny please stand up, please stand up, please stand up?

[wingnutx]

"2/24 Marines" would be 2nd Battalion, 24th Marine Regiment.

"2/3 Special Forces" would be 2nd Battalion, 3rd SF.  They refer to it as B2/3 when it's spoken.

A lot of the division designators (like the 101st) were arbitrary to make some attempt to fool enemy analysts, iirc. There were even some fake units in WWII that only existed on paper, but had their own insignia.

NMCB 17 (my unit) is Naval Mobile Construction Battalion 17. IIRC, all the battalions numbered >10 are reserves.

[Perd Hapley]

"2/24 Marines" would be 2nd Battalion, 24th Marine Regiment.

"2/3 Special Forces" would be 2nd Battalion, 3rd SF.  They refer to it as B2/3 when it's spoken.

The special forces might say "B 2 3," but I think all the rest of us just say the 2 3 part.  

The fact that there is a second battalion of the 24th regiment doesn't mean there is a first battalion or a third battalion, though there may have been at one time.  Don't expect to find any rhyme or reason to the numbers.  They have survived through various reorganizations.

[TarpleyG]

Hah, how's this for confusing...

I was in Headquarter's Battalion, 14th Marine Regiment, 4th Marine Division.

I guess now that I look at it, it isn't as bad as some of them I have seen floating around.

Greg

[Moondoggie]

I can't speak for the Army, but the Marine's system is pretty straightforward.

On the active duty side, there are 12 regiments; 9 infantry (1-9) and 3 artillery (10-12).  Each regiment has 3 battalions.  As others have posted, that's where the fractions come into play.  During WWII, when we had 500K active duty folks vs. about 175K today, there were 6 divisions on paper to confuse the Japanese.  In actuality, they were made up of the same folks who were redisignated after surviving each campaign and going through a refit/reorganization session.

The National Security Act of 1947 requires DOD to maintain 3 active duty combat divisions and 3 air wings in the Marine Corps.  This was to prevent the politically ascendent army and navy from budgeting the Marines out of existence in fits of interservice rivalry.

There are 3 reserve infantry regiments and one reserve artillery regiment in the 4th Marine Division....these are the 23rd, 24th, etc.

1st Marine Division (MarDiv) is made up of the 1st, 5th, & 7th Marines.  2nd MarDiv is the 2nd, 6th, and 8th Marines.  3rd MarDiv is the 3rd, 4th, and 9th Marines.   BTW, according to Marine Corps traditions, the 4th Marines is never allowed to be stationed stateside (They've been in Okinawa since WWII) because they burned their regimental colors prior to surrendering at Corregidor in 1942.

The aviation units are a little more complicated.

[roo_ster]

GunnySkox:

The preceding have covered a bit of it.  The current mix of Division-level units in the Army is a legacy from our wars dating way back.

For instance, I was in the 517PIR (Parachute Infantry Regiment) while in jump school at Ft Benning.  I don't think there are 517 PIRs or any other sort of airborne regiments on the planet, let alone in the US Army.

FWIW, below in the CODE is a quick & dirty generic Army unit/size reference.

Code:

Numbers given are approximate.
Organizations can and usually will become mixed starting at the Company/Troop level

Light Infantry/Airborne  *  Light Infantry/Airborne  *  Light Infantry/Airborne
    Number Soldiers      *  Number component units   *      Component Units
           1             *            N/A            *          Soldier
           2             *        2 soldiers         *        Buddy Team
           4             *       2 buddy teams       *         Fire Team
           9             *       2 fire teams        *           Squad
          40             *        3-4 squads         *          Platoon
          120            *       3-4 platoons        *          Company
          400            *       3+ companies        *         Battalion
           ?             *       2+ battalions       *     Brigade/Regiment
           ?             *       2+ bgde/regt        *         Division
           ?             *       2+ divisions        *           Corps
           ?             *         2+ corps          *           Army


Armored (tank/mech inf)  *  Armored (tank/mech inf)  *  Armored (tank/mech inf)
    Number Vehicles      *  Number component units   *      Component Units
           1             *            N/A            *          Vehicle
           2             *        2 vehicles         *          Section
           4             *        2 sections         *          Platoon
          12             *        3+ platoons        *          Company
          40             *       3-4 compnies        *         Battalion
          120            *      3-4 battalions       *         Bgde/Regt
          400            *       2+ bgde/regt        *         Division
           ?             *       2+ divisions        *           Corps
           ?             *         2+ corps          *           Army


Armored Cavalry (Heavy)  *  Armored Cavalry (Heavy)  *  Armored Cavalry (Heavy)
    Number Vehicles      *  Number component units   *      Component Units
           1             *            N/A            *          Vehicle
           2             *        2 vehicles         *          Section
          4+             *       2-3 sections        *          Platoon
          12+            *        3+ platoons        *           Troop
          40             *       3-4 compnies        *         Squadron
          120            *      3-4 battalions       *           Regt


ARMY COMBAT ORGANIZATIONS
Army organizations are inherently built around people and the tasks
they must perform. Major combat organizations are composed of
smaller forces as shown here.
SQUAD
Leader is a sergeant
Smallest unit in Army organization
Size varies depending on type$(OIn(Bfantry (9 men), Armor (4 men),
Engineer (10 men)
Three or four squads make up a platoon
PLATOON
Leader is a lieutenant
Size varies$(HIn(Bfantry (40 men), Armor (4 tanks, 16 men)
Three or four platoons make up a company
COMPANY
Commander is a captain
Usually 150$(H22(B0 men
Artillery unit of this size is called a battery
Armored Cavalry or Air Cavalry unit is called a troop
Basic tactical element of the maneuver battalion or cavalry squadron
Normally five companies make up a battalion
BATTALION
Commanded by a lieutenant colonel
Tactically and administratively self-sufficient
Armored Cavalry and Air Cavalry equivalents called squadrons
Two or more combat battalions make up a brigade
BRIGADE
Commanded by a colonel
May be employed on independent or semi-independent operations
Combat, combat support or service support elements may be
attached to perform specific missions
Normally three combat brigades are in a division
DIVISION
Commanded by a major general
Fully structured division has own brigade-size artillery, aviation,
engineer, combat support and service elements
Two or more divisions make up a corps commanded by a lieutenant
general

[garrettwc]

Thanks for the breakdown Moondoggie. I think I can finally understand my father's unit designation now. He was 1st Div, 5th Marines in Korea.

[doczinn]

Each regiment has 3 battalions.

When I was in, which was until 2003, 4th Marines was split up, and a battalion assigned to each other regiment. Thus, 1st Marines consisted of 1/1, 2/1, 3/1, and 1/4.

With the ongoing troubles in Iraq, 4th Marines may now have been reactivated.

[Matthew Carberry]

Thanks for the breakdown Moondoggie. I think I can finally understand my father's unit designation now. He was 1st Div, 5th Marines in Korea.

Are you sure he wasn't in 1/5?  As was said, that's usually how the units are called.  If so, he was in 1st Battalion, 5th Marines (Regiment).   We don't really mention the Division number (1st MARDIV in this case) much when identifying units.  With the structure as it is, you can tell the Div. by the Reg. so there's no need to say it.

The Marine Corps is very much a "regimental" system due to our history and the expeditionary nature of how we train and deploy.  The geographical separation (East Coast, West Coast and Islands) leads to differences in attitude and personality.  Also noticeable differences in how they train and fight.

For instance West Coast Marines (1st Div) tend to be better looking and do better with the ladies while East Coast Marines (2nd Div) have fleas.

[wingnutx]

Why does the Navy keep Marines on ships?

Because sheep would be too obvious.

Thank you, try the veal.

[garrettwc]

Thanks for the clarification carebear. That sounds right. When he was telling me the stories there were three designations in the number and for sure there was a 1 and a 5 so maybe it was 1st Division, 1st Battalion, 5th Marines. I'll have to ask him again now that I understand the structure.

[Moondoggie]

One dictionairy that I consulted defined Squid as a lower order of Marine life.

Doczinn; since I retired in '99 I wasn't aware of 4th Marines' Bns  being parceled out to other regiments.  A thought occured to me...I'll bet it was a move to make Marine Regiments more closely resemble their Army counterparts since Army Brigades have 4 line Bns and that is their basic unit of employment.  I've been involved in planning operations and I can easily see the Army theater commander stipulating a minimum number of personnel per the basic manuever elements for all subordinate commands.  The Marines are masters of a concept called "Task Organization", and combining units to form appropriate "packages" of capabilities is one of our hallmarks.  Since the Army is undoubtedly running the show on the ground in Iraq, it's no stretch of the imagination to see how this could come about.

Behind the scenes, you have no idea how bitterly the services quarrel over stuff like this.  If the Army top brass had their way, there wouldn't be a single Marine on the ground in Iraq.  Land warfare and occupation duty are not normally part of the Marine Corps' mission, but every service jealously guards their "relavance" as it equates directly to budget $ from Congress.  It's a small step from "We don't need you guys for this one" to "We don't need you guys at all".

[wingnutx]

One dictionairy that I consulted defined Squid as a lower order of Marine life.

Mine defines a squid as a creature that scoots around the ocean, pooping on marine life.

[doczinn]

since I retired in '99 I wasn't aware of 4th Marines' Bns  being parceled out to other regiments.  A thought occured to me...I'll bet it was a move to make Marine Regiments more closely resemble their Army counterparts since Army Brigades have 4 line Bns and that is their basic unit of employment.

I got to 1st Marines in '96, and it was already so. Don't know when it happened. Another theory for why they would do it (based on nothing other than my own thoughts): It's a way to eliminate all the administration crap of a full regiment, yet still have a regiment's worth of grunts ready. Then if you need another, you just pull 'em all in and staff up a HQ Company.

[Moondoggie]

Yeah, Doc...it's called "Cadreing" a unit.

Back in the '70's after the VietNam drawdowns 7th Marines consisted of about 150 folks.  Just enough to keep it "active".  5th Marines wasn't full strength, either.

The Marines have always been the bastard children of DOD, battling for every scrap of $ we can get.  It's gotten a lot better in recent years...geez a Marine General is even Chairman of the JCS.  I'll bet THAT has Curtis LeMay and others rolling in their graves!  A lot of top brass figured that the Marines would cease to exist after WWII, since the Army now had amphibious landing capabilities.  When Adm Nimitz saw the photo of the flag raising on Mt Suribachi he remarked "This picture gaurantees the existence of the Marine Corps for the next 100 years!"

[Matthew Carberry]

I didn't know Marines were interested in ladies.  Thought they liked boys.

No, see you're thinking of the Navy again where the ship's "pursers" (they carry purses right?) take care of the "coxswains".



The Marine's ARE a department/u] of the Navy....

The MEN's Department.

[Moondoggie]

Squids can cast aspersions till the cows come home.....

at least nobody ever referred to us Jarheads as "Semen".

[Perd Hapley]

Well, if you all had some.

[Matthew Carberry]

Well, if you all had some.

We spent it all in Navy wives and girlfriends.

[Moondoggie]

Ain't that the truth!

[Perd Hapley]

Carebear, that is so wrong.

[Moondoggie]

Sometimes, Fistful, the truth just hurts.

I've boffed more than one squid's significant other, but no squid has ever boffed one of mine.

Deal with it.

Another glass of Beaujolais and I promise to be much wittier and charming.

[Al Lowe]

Hi, everybody,


Like, why is the 101st Airborne Division the 101?

The 101st Airborne started out as the 101st Infantry Division.  As did the 82nd "All American" (that's why they have AA on their shoulder patch.  I might be wrong, but I don't believe the US Army had many permanent divisions prior to WWI.  The primary element was the regiment, and they would be moved around as needed.  This pretty much changed around WWI, and became more solidified in WWII.  In WWII, the primary element became the division, which could be moved from one corps to another as needed.

[Perd Hapley]

Sometimes, Fistful, the truth just hurts.

I've boffed more than one squid's significant other, but no squid has ever boffed one of mine.

Deal with it.

Another glass of Beaujolais and I promise to be much wittier and charming.

Don't worry about me, I was in the Army.  We have access to women that the rest of you can only dream of.  Don't tell anybody that I let you jarheads know about that.

[doczinn]

Well, I can tell you who has the best women, and that's the Air Force.

I know, 'cause I've had two of 'em.