The United States Civil War was the first American war to be documented extensively by photographs, and these photographs have had tremendous impact and importance. During the war and immediately following, the cost and difficulty of reproducing photographs limited their appeal. Economic pressures actually caused Matthew Brady, the most famous photographer of the Civil War, to sell his collection to the War Department. The invention of the half-tone process, which enabled mass reproduction of photographs, renewed public interest in photography and gave historians ready access to photographic materials. As Civil War survivors died, photographs became vital records of detail and lent a feeling of timelessness to the works they illustrated. The ease with which photographs may now be edited through digitized methods means that it is increasingly important to establish the history of each photograph and to record any changes made. (Contains 26 references.) (SLD)