I pulled the following list from GERDES, but I still don't really understand who was in command when. I think that a Colonel L. Featherston was the origional commander, followed by J.M. McNeely, who I think was in command at Shiloh, and then Tappan is elected in the reorganziation at Corinth?

Mcneely, J.M. - Col - Resigned 27 May 1862.
Tappan, J.C. - Col
Grayson, A.D. - Ltc - Kia Shiloh 17 Apr 1862.
Pollard, J.M. - Ltc
Brown, A.R. - Lt Col - Dropped 9 Feb 1863
Duncan, R.A. - Lt Col - Enl 28 Apr 1862 At Tellahoma, Tn Dropped 2 Feb 1864.
Hunt, George B. – Maj
Morgan, James E. - Cpt Acs - Age 28. Res: Somerton, Va.
Mercer, William N. - Adjutant
Stephenson, Hammett L. - Adjutant
Eskridge, B. B. - Sgt Major Enl Mound City, Ar Wounded At Chickamauga.
Warren, Nelson F. - Qm Sgt - Captured Oct 1863 At Deer Creek, Ms.
Wimpy, E.T. Hospital Steward Mound City, Ar Disch 28 Oct 1861.
Collins, Robert J. Ensign - Enl At Madison, Ar Pow A Tft Delaware, Del. -Disch 25 Jan 1865. Released17 Jun 1865.
Butler, Jasper F. - Surgeon - Dismissed 1may1863
Cole, A.W. - Asst Surgeon - Resigned 5 Nov 1862.
Casey, A.M. - Chaplain - Awol From 22 Feb 1863. Dropped. Returned 24 May 1863. Returned To Duty 23 Jun 1863. Resigned 25 Jul 1863.