Confederate and Union both orginized along the same lines....

A Company consists of a group of 100 men, with 4 Sergeants, 8
Corporal's, a First or Orderly Sgt.
A Second Lieutenant, a First Lieutenant, and a Captain. (This Company
can be broken down into platoons, 
of 25 men each, with a Sgt, and 2 Corps. plus an officer....)

a Group of 2 or more Companys can make a battalion.... (Not generally
used in the Civil War, except for
temporary Duties.....

All Ten (or sometimes 12 for Cavalry) Companys form a Regiment.
This regiment is commanded by a Colonel, assisted by a Lt. Col. and a
Major. (if a Battalion is formed, it would be commanded by the Lt. Col. 
and Major)

The orders to create a new Regiment came from the Governor of the State.
He issued orders to raise a Regiment in a certain area, consisting of
several countiess..
(Most states were broken into small departments for this purpose)

He then, (the governor) authorised the raiseing of the troops, and the
call went out.
As the men signed on, they were assigned to a company, and once it hit
its full compliment, 
it was then appointed officers, and sent to a central area, to join with
the rest of the companies.

Early in the War the companies elected the officers that commanded the
company, corps, Sgts, Lt's, and Captains
In some cases this continued well into the war. 


As far as finding out about the different companys, and officers, In
Indiana, and other states, 
there is a set of books called..
"Report of the Adjutant General of the State of Indiana" -1861-1865 
This set has a complete listing of every regiment, and a roster.
In a seperate book, (but same set) is the officer roster.

Also, in Indiana, they have on microfilm copys of all transactions and
letters about a regiment.
Within this film lies letters telling about how the unit was raised, and
information on who was 
chosen for what role, etc. Actually, this can be rather fun reading, as
you read about how the men jockied for
position. Can be really amusing!

Attached to, and unassigned, are simply terms refering to recruits. 
Especially later in the war, (at least in Indiana) when the early
regiments terms expired, they attempted to 
re-sign the veterans. Of Course not all men did rejoin, and also, most
regiments were quite depleted, from
death, desertion, and disabled men. THey often recruited, or drafted in
new recruits. Sometimes these recruits were never offically assigned a
particular company. To be honest, I am not positive why, or what they
did with them, but they were never offically assigned!

I hope this helps explain a bit.....
 



-- 
Your Obedient Servant,
Bart Johnson