Timothy O’Sullivan was first exposed to photography as an apprentice in the New York gallery of Mathew Brady, later moving to Brady’s Washington, D.C. studio managed by Alexander Gardner. During the Civil War, O’Sullivan worked for both of these iconic American photographers, documenting the devastating toll of modern warfare in the United States. At war’s end he struck out for something new, traveling with Clarence King’s 1867 expedition to survey the western frontier. He continued to work with expeditions documenting parts unknown, cementing his reputation as photographer of the American frontier as well as a chronicler of war.