How Are Army Divisions Numbered?

MSN, explainer Answers to your questions about the news. ^ | march-29-2003 | By Phillip Carter

[green team 1999]

How Are Army Divisions Numbered?

By Phillip Carter
Posted Friday, March 28, 2003, at 3:18 PM PT

Anyone watching Iraq war coverage has seen a stream of numbers go by, identifying particular Army divisions—the 101st Airborne, the 3rd Infantry, etc. What do these numbers mean? And if there's a 101st Airborne, what happened to the 100th and 102nd?

The first thing to know is that the Army's divisions were numbered in the order they were created. So the 1st Division was actually the first division; then came the 2nd, 3rd, etc.

There are, of course, gaps in the sequence. Today's Army has eight infantry divisions: the 1st, 2nd, 3rd, and 4th, along with the 10th, 25th, 82nd, and 101st. What happened to the rest of them? Well, the military has cyclically expanded in wartime, creating lots of new units—during World War II, for example, the Army's had infantry divisions running all the way up to the 106th. But during peacetime, most of the war units are deactivated, which accounts for the holes.

How does the Army pick which divisions to keep? Each unit has its own customs and history, and the Army basically preserves the ones with the most glorious lineage. Take the 101st Airborne Division, which has been part of the Army since 1942. During World War II, the "Screaming Eagles" parachuted into Normandy and fought their way across Europe, making a heroic stand at Bastogne during the Battle of the Bulge. The Army has kept the division on active duty ever since. During the same war, the Army's 100th and 102nd Divisions served no less bravely but somewhat less famously. Both were shuttered for good after the war.

TV coverage of Gulf War II also refers to various Army regiments (notably the 7th Cavalry Regiment, which has already tangled with Iraqi forces); but forget about trying to understand that numbering system. For a while, the Army issued regimental numbers in sequence. But the system gave out during the Civil War, when states raised and numbered their own regiments, and became further muddled during World War I, when newly formed federal regiments tried to reclaim the numbers of their Civil War forebears.

To make things more confusing, the Army has a habit of combining many regiments in the same unit. The 1st Brigade, 3rd Infantry Division, for example, includes parts of the 7th Infantry and 69th Armor regiments. It also includes a number of support units, whose numbers often bear little or no relation to the number of the combat unit they support.

Bonus Explainer: Division, regiment, battalion—what's the difference? Divisions have 10,000-to-15,000 soldiers divided in three-to-five combat regiments and a number of support units. Regiments have 3,000-to-5,000 soldiers and include several combat and support battalions. Each battalion has three-to-five line companies of 100-to-150 soldiers apiece. Companies break down into three-to-five platoons of 20-to-40 people, which in turn break down into squads of eight-to-12.

for information and discusion only,not for profit etc,etc.

[Junior]

and a squad equals a mess of Roman legionnaires.

A maniple.

[TankerKC]

...which reminds me of the mnemonic we learned at Air Force basic training: "How many new airmen will get sore feet". That is how we remembered the hierarchal break down of Air Force units, which is as follows:
Headquarters AF
Major Command
Numbered Air Force
Air Division
Wing
Group
Squadron
Flight

[ko_kyi]

Thanks for the reply. So here is a not-too-closely related question:

Are the modern combat elements (squad, platoon, company, battalion, brigade, division, corp, army..did I miss any?) a product of modern (since rifles, anyway) weaponry, or are they the result of how many people can be dedicated to a specific task or set of tasks, and therefore a product of the nature of leadership and command decision methods that go back however far in history?

I realize that is a run-on question, but I just wonder what the rationale is behind the structure.

[Junior]

You're asking a Navy guy this? Our idea of a division is a grouping of workcenters, with several divisions falling under a department.

However, I think formal platoons are a fairly recent invention, dating back only to the First World War. Before that, the company was the basic maneuver element. There were usually a dozen or so companies in a regiment. Battalions were formed ad hoc for specific operations in the 19th century, but the basic units were the regiment and company.

You must remember, prior to the 20th century, available weapons required maneuver elements to be larger to be effective. As weaponry became more effective, the basic maneuver element got smaller, both because it was more effective and because smaller elements made smaller targets. Also, over time, ad hoc elements became more formalized and eventually became permanent parts of the order of battle.

[No Truce With Kings]

"I realize that is a run-on question, but I just wonder what the rationale is behind the structure."

The rationale is that a commander can only handle a maximum of four to five items under the pressure of combat. Thus a fire team leader manages three or four men. A squad leader manages two fire teams plus his comm guy. A platoon leader handles three or four squads. And so on up the line.

Another factor is two up (engaged), one back (reserve), one support unit.

[ko_kyi]

Thanks for the info. So it seems that literal size is determined by the weaponry and tactics, and logical relationship of elements is determined by cereberal limits of average commanders.

[Kay Soze]

Bump

[XJarhead]

My understanding is that a 1st Lt commands a Platoon

To be technical, a Lt. "leads" a platoon. He doesn't "command" it. "Command" doesn't start until you reach company size.

a Captain commands the Company,a Lt Col commands the Battalion, a full Col commands the Regiment, and a two-star commands the Division.

All true.

I guess a three-star commands an Army?

Nope. A three star commands a Corps, which consists of 2+ divisions.

What does a 2nd Lt command?

A 2ndLt. can lead a platoon -- doesn't have to be a First Lt.

Or a Major??

Generally, majors are staff officers on the Battalion Commander's staff. A major may command some special units such as reconnaissance companies, etc. And of course, there's no rule saying a senior major won't command a battalion for a bit while awaiting promotion.

[No Truce With Kings]

"So it seems that literal size is determined by the weaponry and tactics, and logical relationship of elements is determined by cereberal limits of average commanders."

Yep. Kind of comforting. These guys actually *know* what they are doing.

[rabidralph]

(i.e., a Captain in the Army isn't the same as a Captain in the Navy).

When I was in the Navy, stationed at an Air Force base, working at an all-services radio-TV detachment, one of the AF engineers took a phone call from an irate captain complaining about the weak TV signal. The sergeant got testy and told the the captain that the signal would be fixed when he could see clearer reception on his TV, and he angrily hung up the phone. The rest of us at the stationed giggled and asked him who he was yelling at. He said some captain at Yokosuka (a Navy base in Japan). The rest of us stood there with our mouths agape and explained to the AF guy that a captain in the Navy is an 0-6, one rank below admiral, not an 0-3 captain like the other services, a junior officer. Luckily, the guy never called back.

[gcruse]

I was an E-3 in the Navy when one of my civilian friends
jokingly addressed a letter to me as Admiral Cruse.
I got the letter okay, but with a nasty from the Navy
telling me to advise my correspondents of my correct
address.  LOL

[wideminded]

"Today's Army has eight infantry divisions: the 1st, 2nd, 3rd, and 4th, along with the 10th, 25th, 82nd, and 101st.

" ... "Divisions have 10,000-to-15,000 soldiers divided in three-to-five combat regiments and a number of support units."

O.K. Here's a related question that confuses me. Eight divisions only adds up to 80000-120000 soldiers. On C-SPAN about a week ago they were showing a table that gave the year-to-year populations of the regular services. I noticed that the current number of regular Army was somewhere in the 400,000's. So what do the other 300000 soldiers that are not part of one of the listed divisions do?

[Citizen of the Savage Nation]

Thanks for the info. I was thinking about Patton and his 3rd Army, but then those were much different times.

Is it the case then that one-stars serve as XO's to division commanders or flunkies to higher up generals?

I'm also curious as to what rank the British Group Captain corresponds to.

[ZULU]

A phalanx was a Greek formation of several ranks of men armed with long lances (sarissa) and shields which moved ponderously forwards like an unstoppable iron porcupine, smashing everything in its path. Its disadvantage was the difficulty of manoevereing over rough territory or responding to a flank or rear attack. Alexander used it well with cavalry to cover the flanks and rear.

The phalanx was proved inferior to the Legion at the battle of Cynoscephalae where a Roman Army destroyed a phalanx force.

[jackbill]

O.K. Here's a related question that confuses me. Eight divisions only adds up to 80000-120000 soldiers. On C-SPAN about a week ago they were showing a table that gave the year-to-year populations of the regular services. I noticed that the current number of regular Army was somewhere in the 400,000's. So what do the other 300000 soldiers that are not part of one of the listed divisions do?

Support? Everything from the guys at the Tomb of the Unknown, to recruiters in you home town, to unattached artillery, engineers, graves registration, medical, training cadre, base bureaucrats, etc., etc.. And then there is the Pentagon.

I've seen numbers like 5 to 10 "support" troops for every combat soldier. It takes more than a village to field a fighting army.

[Henchman]

How are they numbered? Try 1 then 2 then 3 etc. When you get to the higher numbers, hold your hands over your head and count higher 11 , 12 etc

[XJarhead]

Is it the case then that one-stars serve as XO's to division commanders or flunkies to higher up generals?

Generally, yes. But those are only their "combat" billets. All officers also have non-combat assignments during their careers. That might include things like recruiting, working as an instructor at a school, attending school, working at a base as a staff officer, etc.

I'm also curious as to what rank the British Group Captain corresponds to.

I'm guessing colonel, but that's just a guess.

[DannyTN]

How Are Army Divisions Numbered? If you are the US, your number is "1". And if you are fighting the US, your number is "up".

[No Truce With Kings]

Some belong to independent regiments or brigades -- such as the 3rd Armored Cavalry Regiment, the 197th Infantry Brigade, or the 173rd Airborne Regiment.

Others belong to artillery units -- typically battalions or brigades. While much artillery is attached to divisions, other units are part of corps or army formations. These independent units are added to divisions on an as-needed basis, to support operations. There are also a lot of aviation units -- both transport and attack -- typically brigades.

Similarly there are combat support units -- Air Defense Artillery (including Patriot units), Combat Engineers, Military Police, Chemical Warfare Units, etc., that operate independently of divisions. These are typically battalions or brigades.

There are also support units -- ordinance, maintenance, transportation -- that support and supply the combat and combat support units. These, too, are typically organized in battalions, or brigades.

There are also training units, like the Ft. Benning Infantry School, Ft. Sill Artillery School or Ft. Bliss Air Defence School, that have training cadres.

Finally there are the Really-REMF units of the Judge Advocate General's Corps, the Army History Units, and Admin warriors of Pentagon, where the basic element of command is a GSD (grey steel desk).

It adds up.

[Dajjal]

BTTT