The information from that microfilm roll is excellent and exactly what I'm looking for. Just one question: it mentions "Parson's brigade" but as far as I know this brigade was not yet formed and when it was it would serve in the Trans-Mississippi theater as it says here "Parsons's Brigade, a Confederate brigade during the Civil War, was organized in the autumn of 1862 to serve as cavalry for the Army of the Trans-Mississippi then forming in Arkansas. For much of the war the brigade was commanded by Col. William Henry Parsons, who had raised the Twelfth Texas Cavalry Regiment in the summer of 1861."

https://tshaonline.org/handbook/online/articles/qkp01

It sounds like they were still a "paper" unit that hadn't been formed yet. So is this a case of units being left on the order of battle east of the Mississippi for a while in anticipation of them being sent east but they actually stayed west of the Mississippi? Because I don't think Parson's brigade was at Corinth in May 1862.