9th Regiment, Mississippi Infantry
9th Infantry Regiment, organized at Corinth, Mississippi, in March, 1861, recruited its men in Tate, De Soto, Marshall, Tishomingo, Quitman, Lafayette, and Panola counties. After serving in Florida and fighting at Shiloh, the unit saw action in Kentucky. Later it was placed in General J.P. Anderson's, Tucker's, and Sharp's Brigade, Army of Tennessee, and fought at North Carolina. It was organized with 930 men, sustained 53 casualties at Munfordville, and lost 8 killed, 71 wounded, and 5 missing at Murfreesboro. Of the 332 engaged at Chickamauga, more than thirty percent were disabled. The regiment was briefly consolidated with the 7th Mississippi Regiment and in December, 1863, totalled 468 men and 252 arms. It surrendered with 43 officers and men. The field officers were Colonels James L. Autry, James R. Chalmers, W.C. Richards, and Thomas W. White; Lieutenant Colonels S.S. Calhoun, Thomas H. Lynam, William A. Rankin, and F. Eugene Whitfield; and Majors Albert R. Bowdre, J.M. Hicks, Andrew G. Mills, and J.E. White. 
The 9th Mississippi Infantry Internet site has a longer history taken from Dunbar Rowland's Military History of Mississippi, 1803-1898.
Regiment Companies with the County of Origin
Men often enlisted in a company recruited in the counties where they lived though not always. After many battles, companies might be combined because so many men were killed or wounded. However if you are unsure which company your ancestor was in, try the company recruited in his county first.
Companies Comprising the Original ["old"] 9th Mississippi Infantry:
Company A - [also listed as Co. C] - (Corinth Rifles) - raised in Tishomingo County
Company B - (Home Guards) - raised in Marshall County
Company C - (Lafayette Guards) - raised in Lafayette County also listed as Co. H
Company D - (Jeff Davis Rifles) - raised in Marshall County
Company E - (Horn Lake Volunteers) - raised in DeSoto County
Company F - (Quitman Rifle Guards) - raised in Marshall County
Company G - (DeSoto Guards) - raised in DeSoto County
Company H - (Panola Guards) - raised in Panola County also listed as Co. K
Company I - (Senatobia Invincibles, aka Invincibles) - raised in Panola County
Company K - [also listed as Co. A] - (Irrepressibles) - raised in DeSoto County
The regiment was reorganized in 1862 and became known as "the new Ninth".
Companies Comprising the ["new"] 9th Mississippi Infantry:
Company A - (Capt. Wallace’s Company) - raised in DeSoto County
Company B - (Capt. Hollohan’s Company) - no county of origin specified
Company C - (Capt. Mills’ Company) - no county of origin specified
Company D - (Capt. Calhoon’s Company) - no county of origin specified
Company E - (Vicksburg Cadets [formerly Hill City Cadets, Co. F, 10th MS Infantry]) - raised in Warren County
Company F - (Capt. Keith’s Company) - raised in Marshall County
Company G - (Capt. Spears’ Company) - county of origin not specified
Company H - (Semmes Rifles) - raised in Madison County
Company I - (Capt. Braden’s Company) - county of origin not specified
Company K - (Capt. Monroe’s Company) - raised in Marshall County
Information from Military Annals of Mississippi: Military Organizations which Entered the Service of the Confederate States of America from the State of Mississippi, by John C. Rietti, Spartanburg, South Carolina: Reprint Company Publishers, 1976, p. 69, FHL book 976.2 M2r. includes roster.
- Beginning United States Civil War Research gives steps for finding information about a Civil War soldier. It covers the major records that should be used. Additional records are described in ‘Mississippi in the Civil War’ and ‘United States Civil War, 1861 to 1865’ (see below).
- National Park Service, The Civil War Soldiers and Sailors System, is searchable by soldier's name and state. It contains basic facts about soldiers on both sides of the Civil War, a list of regiments, descriptions of significant battles, sources of the information, and suggestions for where to find additional information.
- Mississippi in the Civil War describes many Confederate and Union sources, specifically for Mississippi, and how to find them.. These include compiled service records, pension records, rosters, cemetery records, Internet databases, published books, etc.
- United States Civil War, 1861 to 1865 describes and explains United States and Confederate States records, rather than state records, and how to find them. These include veterans’ censuses, compiled service records, pension records, rosters, cemetery records, Internet databases, published books, etc.
- Howell, H. Grady. For Dixie Land, I’ll Take My Stand!: A Muster Listing of All Known Mississippi Confederate Soldiers, Sailors, and Marines. (Chickasaw Bayou Press, 1998), FHL book 976.2 M2
- Rowland, Dunbar. Military History of Mississippi, 1803-1898: taken from the Official and Statistical Register of the State of Mississippi, 1908. (Spartanburg, South Carolina: Reprint Company), FHL book 976.2 H2
- National Park Service, The Civil War Soldiers and Sailors System (accessed 11 January 2011)