This may give a hint. This is from the NPS Soldiers and Sailors website. It is finally back up. I know in May 1862 they were at Corinth. BTW, McNair was my 3xgreat grandmother's cousin.

4th Regiment, Arkansas Infantry

4th (McNair's) Infantry Regiment [also called Southwestern Arkansas Regiment], assembled at Miller's Springs, Lawrence County, Arkansas, recruited its companies in Calhoun, Hempstead, Lafayette, Montgomery, Pike, and Polk counties. After fighting at Elkhorn Tavern, the unit was sent to Kentucky where it was active at Richmond. It then was assigned to General McNair's and D. H. Reynold's Brigade, Army of Tennessee. Soon after the Battle of Murfreesboro, the 4th Arkansas Battalion merged into the regiment and in August, 1863, the 31st Arkansas transferred to the 4th. It was involved at Jackson, participated in the campaigns of the army from Chickamauga to Atlanta, saw action in Tennessee under Hood, and was engaged at Averasboro and Bentonville. This unit was organized with 695 men, and reported 55 casualties at Elkhorn Tavern, 23 at Richmond, and 79 at Murfreesboro. The 4th/31st/4th Battalion lost twenty-four percent of the 385 engaged at Chickamauga. Few surrendered on April 26, 1865. The field officers were Colonels Henry C. Bunn and Evander McNair, Lieutenant Colonels James H. May and Samuel Ogden, and Major Jos. B. McCulloch.