George W. Northup was commissioned captain of the 23rd Kentucky Volunteer Infantry (Union) in September 1861 and rose to lieutenant colonel, commanding the regiment at the Battle of Nashville in December 1864. He mustered out in December 1865 and settled in Louisville, Kentucky, working as a railroad agent and becoming a prominent Freemason. Northup died in 1906 at the National Home for Disabled Volunteer Soldiers in Dayton, Ohio.