Judith
I posted this on the Prisons board as a reply to your original request for information. But I am not sure that you would have read it there.
I did a little searching and as I suspected Ephriam Frye and William Johnson are both listed as being captured at Mazzard Praire, Ark. on July 27th 1864, They are listed as Prisoners of War at Camp Ford, at Tyler, Texas. They were released from Camp Ford May 22nd, 1865.
http://www.kansasheritage.org/research/campford.html