William Starke Rosecrans (1819-1898) commanded the Army of the Cumberland during the Tullahoma campaign and at the battles of Stone's river and Chickamauga during the U.S. Civil War. After the war, he moved to Los Angeles, California and became an advocate for railroad building and Mexican trade in the West before being appointed as the U.S. Minister to Mexico (1868). He later served in the U.S. Congress (1881-85), and as the Register of the U.S. Treasury (1885-93). The collection consists of correspondence, papers, diaries, accounts, photographs, maps, realia, and related printed material of Major General William S. Rosecrans and his family. The papers cover nearly a century of American history and are comprised of materials from three generations of the Rosecrans family.