Responding to Jamie's input: In the context presented, Camp Allen was probably at Shreveport. The surrender of the Confederate Trans-Mississippi Department is dated May 26, 1865 at New Orleans (not signed by General E. Kirby Smith until June 3rd at Galveston). The Confederate army, those still in the ranks, were at various post scattered around the T-M Department. Covered by the "New Orleans" surrender, they would have been released on parole from their duty stations. However, most of the soldiers had gone home before the surrender and were required by the surrender protocols to report into a Federal parole center nearest their homes to be accounted for and released on parole.
I think I have read in some Arkansas or Missouri CMSR's about men being paroled at Camp Allen in Shreveport at the end of the war, but I wouldn't want to bet the farm on it without having one of these records in hand.