It was founded under its original name in Cincinnati in 1854 by George Bickley, who also named its members Copperheads.  
The last incarnation of this group was curbed by Indiana governor Oliver Morton.  This group manifested itself in John Hunt Morgan's raid into Kentucky, Indiana, and Ohio, but garnered little support.  This organization's last leader was Clement Vallandigham when it was known as the Order of the Sons of Liberty, prior to which it was called the Order of American Knights.  It was founded under its original name in Cincinnati in 1854 by George Bickley, who also named its members Copperheads.  FTP, identify this secret order of Southern sympathizers in the North during the Civil War.
The last incarnation of this group was curbed by Indiana governor Oliver Morton.  
Knights of the Golden Circle (prompt on early Copperheads)