A. If you haven't already, obtain the ancestor's compiled military service record (CMSR) from the National Archives. (You can view Confederate records and a few Union records online at the subscription site Footnote.com.) In addition to the standard "envelope," the CMSR may also include an internal jacket of "personal papers," such as any record of the soldier's being a prisoner of war.

For specific prisoner of war records, consult the Archives' record group 249, Records of the Commissary General of Prisoners. The 347 series in this group include records relating to the parole of federal prisoners, prisoners held in Confederate prisons including Andersonville (Ga.), Confederate prisoners of war held in Union prisons, and claims filed by Union prisoners of war. Information on Confederate POWs is also in record group 109 (National Archives microfilm publication M598); these records are available in 145 rolls of microfilm from the Family History Library (FHL). The FHL also has some records of specific prisons, lists of those paroled at particular locations, and memoirs of POWs.