Photograph of Fort Walla Walla, taken on May 1, 1859. The photograph was originally owned and may have been taken by Frederick Tracy Dent (1820-1892). Dent served as captain of the 9th United States Infantry at Fort Walla Walla. In 1859, Fort Walla Walla was a cavalry outpost for the United States military located in the Washington Territory, now Washington State.