The photographs of Hubbard Pryor were made into woodcuts by an artist at Harpers' Weekly and appeared in the July 2, 1864 issue (almost exactly a year after the even more famous woodcut of "Gordon a Slave" with a whipped back). The note on "The Escaped SLave and the Union Soldier" has some (apparently inaccurate) biographical details, but does not include Pryor's name. See http://www.sonofthesouth.net/leefoundation/civil-war/1864/july/slave-soldier-union.htm