Col. Thomas’ 28th Louisiana Regiment of Infantry was organized at Camp Moore, May 3, 1862 . . .

. . . The regiment at this time, consisting of about 710 men, remained at Camp Moore until May 18th, when they were moved to Vicksburg. We were of course not known at the War Department until our first monthly return was made, June 10, 1862. We had been organized under orders from department headquarters as the “28th Louisiana Infantry,” some time in the latter part of May, 1862. A regiment of infantry had been organized at Monroe by Col. Henry Gray, and which also took the name of the 28th Louisiana, but as it served altogether on the west side of the Mississippi river, continued to carry the same name until the close of the war. We were known at the War Department as the “29th Louisiana,” but elsewhere as “28th Louisiana.”

Our regiment was engaged in all the battles at Vicksburg, losing Sergeant John Johnson and several others on the “Ram Arkansas” on the 15th of August, and about 50 killed and wounded at “Chickasaw Bayou” on the 28th and 29th of December, 1862. . .

. . . .The investment of Vicksburg was completed on the 17th of May, 1863, and we were constantly under fire until the surrender on the morning of July 4th.

http://thesouthsdefender.blogspot.com/2010/03/reminiscence-of-28th-louisiana-infantry.html