As you know General Grant had put a stop on prisoner exchanges in April of 1864 for the most part. However there were exceptions. It would have been a bad time to be captured by the enemy starting in May 1864 or after and the Red River Campagin in Louisiana would begin in May of 1864. I expect there were countless issues to be considered some of which may include a veteran regiment taking the prisoners as compared to a regiment with little war experience. Or in the Red River campaign were Confederate prisoners taken by black regiments treated different than a white Union regiment. The condition of the Confederate prisoners ie sick or wounded. The number of Confederate prisoners taken etc. Any Confederates willingly to take the oath may have been grouped seperately and given a little extra food and attention at best. A physcial description may have been in order ie the following information collected. Age, color of hair and eyes. Unit information, name, height, complexion of skin, rank. The Union soldiers would have seperated the officers from the enlisted as soon as possible. The first few days of capture the prisoners would have been secured well within the Union lines and talking may have been prohibited ie no communication making plans for escape. Depending upon the guards or orders given to the guards perhaps no sudden movement and the prisoners may have been ordered to lay face down or upon their backs.

Whenever I have a question I sometimes refer it to Dr. Dick Sommers of the Army War College in Carlisle, PA. His phone number at his office is 717-245-3096. Dr. Sommers is easy to talk to and in my opinion probably one of the leading Civil War authorities in America today. That is not to say that people like Hugh Simmons (just to name one) at this site may very well be able to answer your question in greater detail.