Correspondence, journals, biographical materials, financial records, orders for agricultural equipment and supplies, printed matter, photographs, and other papers relating chiefly to Capron's role as agricultural adviser to the Japanese government in the agricultural development of Hokkaido (1871-1875). Includes material relating to Capron's service as Union Army officer and as U.S. commissioner of agriculture (1867-1871). Includes Capron family correspondence and an manuscript of Capron's autobiography. Correspondents include Horace Greeley, Ulysses S. Grant, and William T. Sherman.