States Secretary of War In office March 7, 1853 – March 3, 1857 President Franklin Pierce Preceded by Charles Magill Conrad Succeeded by John Buchanan Floyd United States Senator from Mississippi In office August 10, 1847 – September 23, 1851 Preceded by Jesse Speight Succeeded by John J. McRae In office March 4, 1857 – January 21, 1861 [ 1 ] Preceded by Stephen Adams