Are there records for POWs captured at Arkansas Post?

Until now, I have been unable to learn anything about James J Shoemaker's service, or about him. I believe he was born in MS, 1839, the oldest of the Shoemaker brothers.

He and his brother, Ambrose M Shoemaker/A M Shoemaker, are on the roster of Dallas Artillery, Hart's Battery, or Second AR Field Battery, when that was reconstituted August 1, 1862. Listed I found: Shoemaker, Ambrose M--Private. Enlisted at Napoleon, August 1, 1862 and, Shoemaker, James J--Private. Enlisted at Napoleon, August 1, 1862, captured at Arkansas Post.

Ambrose (A M) is not identified as "captured" -- then, what happened to him when the unit surrendered Jan 1863? Other records indicate he served later in the Co A, 37th Arkansas Infantry.

I have not found record of either man after the War.

Any help or direction will be much appreciated.