Reverse of a carte de visite from the field studio of Hall & Judkins, photographers operating near the headquarters of the Union XXIV Army Corps during the 1864-1865 Petersburg-Appomattox Campaign. A period inscription identifies the sitter as Sgt. Silas H. Holbrook of Constantia, Oswego County, New York, a rare instance of a Civil War portrait subject being named directly on the mount. Project: 218701