Context: Hachaliah McMath, Jr. is my 3rd great-grandfather on my father's maternal side of the family.
After his capture in Farmville, Virginia following the Battle of Saylor's Creek, McMath was transferred to City Point, VA (Grant's headquarters) and then on to Newport News, Virginia. From what I can determine, the Newport News area was occupied by Union troops for a large portion of the war. Camp Butler was heavily fortified, as seen in the lithograph below - from the "Civil War in Newport News" collection of the Newport News Public Library System:
While this lithograph was created in 1861, it still gives a great overall impression of the look of Camp Butler in 1865. Views possibly similar to those seen by my 3rd great-grandfather during his time as a POW.