How was Joey transformed before going off to war

Chapter 5 begins with a description of Joey's early, uneasy adaptation to cavalry training. The new routines that Joey must fall into are physically demanding, and are made all the harsher by the temperament of Joey's rider, Colonel Samuel Perkins. Though neither violent nor short-tempered, Perkins is determined and demanding. Fortunately, Joey finds solace in the visits of Captain Nicholls, who talks to Joey in a soothing manner and relates his thoughts about the war. The officer also draws Joey's portrait in the course of these sessions.