Thanks for the terrific responses guys! I checked out AlphaTea's links, and thought the article was good enough to bear posting here...
"The other day, I gave my mom my new card, and she asked how to read ( 1-186 IN), my National Guard unit. As I explained the terminology to her, I realized that many of the things that I take for granted are not available to people who are not familiar with the military. One of these things is an understanding of the various 'building blocks' that make up all military units. So this article is devoted to an explanation of military unit designations and basic organization. This will be primarily about ground forces, but I'll throw in just enough about the Navy and Air Force to really confuse everyone!
The first thing to remember is that confusion is normal, because every country is slightly different in their use of combat unit designations, though they all apparently use very similar names. Also, names can vary somewhat within the same country, depending on the type of unit. So this is just a guide, to provide general understanding. I'll use the Infantry as the basis for the my explanation, with some branching out to other Arms and Services.
The smallest official formation is the squad, or section. This name appears to vary by country. The infantry squad is made up of from seven to eleven soldiers, and is led by a Non commissioned officer. Tank squads are 4 or 5 men and their vehicle. (The issue of ranks is another confusing area. A squad leader in the British Army is a Corporal, while the U.S. Army authorizes a Staff Sergeant. They do the same job, but one army has maintained pretty much the same rank structure for a century or more, and the other has created more and more ranks, until 30% of its force consists of 'sergeants' of varying levels.)
Ground forces are built, more or less, in pyramids, with three smaller units making up one of the next larger size. Therefore Three squad/sections are the basis for a platoon. As units increase in size, they require extra levels of leadership and more support. A platoon also has a headquarters, consisting of the platoon officer, the platoon sergeant, and one or two radio telephone operators. An additional infantry squad is sometimes added, or a weapons squad made up of machine gun and mortar crews, and anti tank specialists. Total strength of around 40 soldiers. A platoon is normally commanded by a Lieutenant, the least experienced of the officer ranks. He is advised and assisted by his platoon sergeant, who normally is well experienced. Armored units will have a vehicle per squad, plus one for the platoon leader and one for the platoon sergeant.
Three platoons make up a company (or troop, if you're cavalry). An additional platoon may include more crew served weapons, and the company headquarters has a few specialists in supply, maintenance, administration and communications. A company usually has between 100 and 150 men and is commanded by a Captain or a Major.
A Battalion (or Cavalry Squadron) breaks the mold by having 4 or 5 companies. Three are the basic type for the Battalion, one is, again, extra crew served weapons. Mortars, anti tank systems or heavy automatic weapons may be included. This company may also have a scout or reconnaissance platoon. The Headquarters company provides support to the rest of the companies with its platoons of communications, medical, transportation, and maintenance specialists. Battalions can run anywhere from 500 to 1000 men. The commander is a Lieutenant Colonel.
The Regimental and Brigade levels are where it really gets confusing. Check
www.regiments.org for an excellent treatment of British terminology and regimental history. This is the best site I've found for explanations, as so many countries use the British model as a basis for their organizations.
The Regiment is not 'really' a combat unit. (except in those cases where, maybe it is...) In the past, regiments were the basic combat formation and consisted of about a thousand men, in theory. Since regiments were raised by their colonels, they didn't always reach full strength, and once they lost strength in combat, it might not be replaced unless the Regiment returned home for recruiting.
Today, the Regiment is more the repository of unit history, morale and soldier esprit de corps. Since it is not a discrete tactical formation, a regiment may have any number of battalions. These battalions all get assigned to Brigades and Divisions, and are not under 'Regimental' control. A Regiment has a Colonel commanding, except that his position is usually honorary and he is retired.
A Brigade comes in two basic flavors, Divisional and Separate. A Divisional Brigade is really a Regiment in disguise. It is commanded by a Colonel and controls, usually, three Battalions, for a total strength of almost 2000. Rather than having extra units to provide specialized functions, the Brigade depends on the Division to provide any services it can't on its own.
A Separate Brigade is one that is not a part of a Division. Besides its Battalions, it also controls extra support units that would normally be under Division control. These may include an artillery Battalion, a Support Battalion (with transport, maintenance and medical companies), and separate Companies or platoons of Cavalry scouts, Military Police, Air Defense, Intelligence or others. Total size is around 4500 soldiers. The Separate Brigade is commanded by, what else, a Brigadier General.
A Division is the next step up from Brigade, and is the highest level that is, nominally, one type of combat formation (Infantry, Armor, etc.) A U.S. Division is almost 15,000 soldiers and includes virtually every combat branch of the Army. The three Brigades may all be one branch, or they may be any mix of Infantry, Armor, Cavalry, or Aviation. Some Divisions have only two Brigades, some may have more than three. A Major General is usually the commander.
Every level above Division is somewhat amorphous. The Corps is commanded by a Lieutenant General and controls anywhere from two to five divisions. It's tailored for whatever task is at hand and may look completely different from one operation to the next. There is no telling how many soldiers may be assigned to a Corps.
An Army (as distinct from THE Army) is a grouping of Corps, again in whatever number meets the current situation. The last time that Corps or Army operations took place was probably during the Gulf War. Army Groups are just that. Lump all the 'Armies' in one geographic area together for command purposes and you get a group. Lump everything together for, say, the Pacific, and you have a theater, commanded by someone like Eisenhower, MacArthur, Zhukov or Mountbatten.
Units are frequently spoken of in abbreviations, such as "First of the Ninth Cav" or, First Battalion, Ninth Cavalry Regiment or "Second of the 1-6-2 Infantry" or Second Battalion, One Hundred Sixty Second Infantry Regiment. The Navy and Air Force don't have regiments. The Air Force is pretty much limited to Squadrons and Wings, as far as units that airmen identify with. People outside the service may not understand the terms fully, but they feel that they do. The Navy is simpler yet. Sailors tend to identify with the individual ship they serve on, and very few people care a great deal about which Carrier Battle Group that ship is a part of.
The different military services use a variety of units other than those I've mentioned. A new unit can be given almost any kind of name. The site at:
http://www.geocities.com/Pentagon/9059/u... gives the entire current U.S. Order of Battle; Army, Navy, Air Force and Marines. He doesn't mention the Coast Guard, but that Service doesn't take its place in that order until a war starts. This exhaustive listing provides names, organization, command relationships, and also links to those units that maintain web sites. Look at this list for an idea of how the U.S. military is put together."
Bruise