One minor correction --
The number of dead (for both sides) in the Battle of Shiloh on April 6-7, 1862, is stated as 23,746. This is the approximate number of casualties (killed, wounded, missing and captured) during the battle. If there were that many killed during the battle, the total number of casualties would be something like 450-475,000.
The 6th and 9th Texas Cavalry Regiments (dismounted) served with the 3rd Arkansas Cavalry in Col. Phifer's Brigade of Gen. Daniel H. Maury's Division. You should expect to find good information on the activities of this brigade in sources for the two Texas regiments. It certainly seems as if Maury's Division remained in camp near Tupelo MS for most of the summer of 1862.