Fascinating! Mom's grandfather was the first of the 31st Mass to get shot at Bisland on April 13th. He was in the hospital in your home town for a while. There's nothing in his service record to indicate he was taken prisoner when Brashear City was taken so I assume he was moved first. He was hit in hte head so he might have been left and more mobile prisoners taken. No information there.
A friend of mine who recently retired is enjoying tracking the exploits of a forebear in the 4th Mass. who were also involved. He has the time to do extensive research. He has found a couple of Mass. State resources that include collections of correspondence between the regiments and the State. I hope to visit one of these to see if the records include reports about Pat Duggan pvt., A co., 31st Mass. V.I. to add detail to the story.
I will save and use your e-mail as a resource and will share it with my friend researching the relative in the 4th Mass. Thanks for getting in touch.