Primarily Civil War papers of Lieutenant Hinkley, Waupun, Wisconsin, of the 10th Wisconsin Infantry Regiment, Company K, including correspondence relating to his company; a diary; letters to his family, some written from Libby Prison; a program for the 1905 reunion of the 10th Wisconsin Infantry; and a number of essays written by Hinkley in his later years, recounting experiences at Libby Prison and prison escape attempts, a return to Gettysburg in 1888, and battle descriptions of Stone River, Chickamauga, and Chaplin Hills (Perryville). Additional materials, mostly military records of the Waupun rifles (Company K of the Wisconsin 10th regiment) and a school certificate are available in original form at Wisconsin Historical Society.