There are two sources: the National Archives in Washington, DC; and, the State of Mississippi Archives in Jackson, MS.

The National Archives in Washington DC
The Compiled Military Service Records for Civil War soldiers are housed at the National Archives, Washington, DC. Procedures are in place whereby individual soldier service records may be mail-ordered from the Archives. (If by chance you are in the DC area, you can search the records yourself on microfilm at the National Archives.)

The first step in a mail-order search at the National Archives requires that you obtain from the National Archives copies of their NATF Form 80, National Archives Order For Copies of Veterans Records. Copies of the NATF Form 80 can be obtained by writing:
          Military Service Branch (NNMS)
          National Archives and Records Service National Archives
          8th and Pennsylvania Avenue, NW
          Washington, DC 20408.

Once NATF Form 80 has been obtained, fill out the form and mail to the address specified in the instructions accompanying the form. Upon receipt of the completed NATF Form 80, a staff person at the National Archives will perform a search of the Civil War records. If they find some records, they will inform you by return mail and tell you the cost associated with reproducing and mailing the records. (Cost is very reasonable, usually less than $10.00.) Upon receipt of your payment, they will produce a copy of the records and mail them to you. It is important to remember that a successful search depends on you providing the searchers with as much information as possible including: the soldier's full name, his military unit (e. g., 16th Mississippi, Company F), dates of service (if known). It will usually take a few weeks to get through this whole process, but it is well worth the effort.

The State of Mississippi Archives
These archives are located in the Old Capital in Jackson. Write to:
          Miss. Dept of Archives and History
          P. O. Box 571
          Jackson, MS 39205

Send the same information as provided to the National Archives. The State of Mississippi Archives works much like the National Archives and will work with you to find the available records.