My work is preliminary, but I have some particular information. The woman in question is Margaret Hefferan Reynolds from New Orleans. She left New Orleans for the Confederate haven of Mobile, but some how was arrested in Vicksburg, August 18, 1864. She was sentenced to confinement (I haven't discovered the charge) at Alton Military Prison, where she died March 18, 1865, though there is some inconsistencies in the federal records. She died of typhoid malaria fever, and is buried in one of the city's "Catholic Burying Grounds". A friend named "Nannie D" placed an obituary in the New Orleans Daily Picayune, April 9, 1865, p 4, c5, identifying her as the daughter of the late Charles and Mary Hefferan and the wife of Thomas Reynolds, all at one time residents of New Orleans.
I teach history at Tulane University, School of Professional Advancement.