I am researching my husband's gggrandfather, Daniel Costigan, who enlisted in Battery B, 1st Regiment Artillery on Nov 20, 1861. He was taken prisoner at Shiloh, Tenn on April 6, 1862 and "paroled". He died from "disease" on August 14,1862 in Detroit. I read that these prisoners of war were "traded" in January 1863. Just wondering if anyone has any information as to why Daniel would have been released before the others. I thought it might have been due to illness but read that 33 others died from disease while captive. Thank You for a great website.