A Magazine Guard detachment poses before their guardhouse at the Mare Island Navy Yard, California, 1917. Armed with Springfield M1903 rifles and bayonets held in ceremonial crossed formation, these servicemen were responsible for securing the naval station's ammunition magazine during the period of U.S. mobilization for World War I. Mare Island, established in 1854, served as a critical West Coast Navy shipbuilding and ordnance facility throughout the war. Project: 218551