Who is Cuff from Behind Rebel Lines: The Incredible Story of Emma Edmonds, Civil War Spy and what is their importance?

Emma's first espionage mission found her taking on the identity of a black male slave she named "Cuff". Her disguise included patched overalls, a red bandanna and a curly black minstrel wig. As Cuff, she was able to blend in at the enemy camp and cellect valuable information about the Confederate's plans and equipment.