Doc Campbell's name was John M. Campbell. Source: James Browning in a list he sent me titled: Confederate Guerrillas and Those Who Rode With the James Boys.
Given (G. N./Givens) Horn(e) was born in 1843 in Kentucky to Richard & Mattie F. Horn. Father born in North Carolina; Mother born in Virginia. Another name given for his mother was Irene Lucille "Michelle" Lumford; her parents were Bennie Lee & Irene Lucille Lumford. 1860 Cass County Missouri census shows he had one sister, Sarah F.; and 2 brothers, Thomas M. & Richard C. Horn. Nothing is known of he survived the war or what became of him after the war. Source: Joseph K. Houts, Jr., QUANTRILL'S THIEVES, p. 145.
I hope this helps.
Rose Mary Lankford