Rebelling against the nineteenth-century compulsory peacetime military service of his fatherland, Bavarian-born Christian Barthelmess demonstrated his independent spirit by migrating to America and spending the greater part of his life in the United States Regular Army. Beginning as an army musician, he soon developed his avocation of photography to such an extent that it gradually supplanted his regular assignments.             Never a man to limit his interest to mundane daily affairs, Barthelmess was keenly aware of the significance of the place and time in which he lived. While serving on the western frontier of the United States during post–Civil War days, he was “catching shadows” in his little black box, as the Indians described photography. His photographs preserved many details of military life on the western plains. Barthelmess captured what the men there looked like, details of their equipment and activities, their actions at ease and under stress, and the historic events of that time and place.   Including more than one hundred of Barthelmess’s fine photographs,
Photographer on an Army Mule
is an important contribution to the history of the nineteenth-century American West.