Given the following context:

The film begins with a U.S. Army commander dictating a report.  Held prisoner in the commander's office, in a fort that has been almost totally destroyed, is the Arapaho Indian war chief, Hanu.  He says very little.  Within the fort's ruins have been found a single grave and a Colt pistol once owned by a gunman Hanu describes as a "quiet, lonely man..." At this point the action of the movie commences.
A wandering gunman, Chuka, rides into an Arapaho camp. It is winter and everyone in the camp is starving, so he gives them some food. Shortly afterwards Chuka crosses paths with a stagecoach taking Mexican passengers Senora Veronica Kleitz and her niece Senorita Helena Chavez through the territory.  Chuka and Kleitz look hard at each other. Suddenly mounted Arapaho warriors, led by Hanu, surround the coach.  Everyone connected to the stagecoach expects to be killed, but Hanu recognizes Chuka and the braves simply ride on.
Chuka accompanies the coach to a nearby U.S. Army fort.  The outpost's commander, Colonel Stuart Valois, is worried the Arapahos may have ambushed his overdue patrol and refuses to allow the civilians to leave. He sends out his scout Lou Trent to reconnoiter, but the horse returns without the rider.

answer the following question:

Who sees the wandering gunman and leaves? 

Hanu