Found out more information about these prints. I spoke with Jan Hinshaw, a relation of the two men discussed in the letter. Jan emailed me this information:
They managed to get to Indiana by the fall of 1863. When Mary Barker
Hinshaw and her cousin Elizabeth Barker Hinshaw learned that their
husbands were alive and in Indiana, they loaded some provisions and
their four children into a covered wagon and headed westward six hundred
miles across the mountains in the early fall of 1864, during the
darkest days of the war. They arrived in Indiana in the spring of 1865.
The story of Thomas & Jacob Hinshaw has been published in "Retreat
from Gettysburg: Lee, Logistics, and the Pennsylvania Campaign" by Kent
Masterson Brown (UNC Press, 2005), and in "Mary Barker Hinshaw, Quaker",
by Seth Bennett Hinshaw (Whittier College library). There's a briefer
version of their story that I included on Thomas Hinshaw's page (above)."
I took to the internet and discovered the Civil War Talk website and forum. I joined and posted a short summary of my finding. Relatively quickly, I was informed that the photo was probably one of the most famous Civil War photos and is knows as "The Three Prisoners at Gettysburg." According to the author of the post and verified through multiple online resources, the photo was "taken near the Lutheran seminary and across the
street from Robert E. Lee's headquarters around July 5/6 1863."
If you do a search online for "The Three Prisoners at Gettysburg," you will find plenty of information about the photo. That appears to confirm that the photo has nothing to do with the letter, even though they are both from the Battle of Gettysburg period of the Civil War.
At this point, I have multiple inquiries to different people, including the Hinshaws about whether or not they have any interest in obtaining the framed prints. Even though they are copies, they both tell awesome stories...perhaps worth of a movie. Two brothers torn from their home forced into military service, dealing with issues of faith and war, present at Gettysburg, escaping only to be arrested and sent to jail, excused by the President of the United States, moving across country to be with their family! Exciting stuff.