This is based on the lucky shot made by Billy Dixon at the Second Battle of Adobe Walls.
This story goes 10 minutes before the opening credits begin.
Wagon Train Tracker: First major backtracking for the Season 7 train. References are made to Raton Pass, New Mexico and "Fort Crowder" (probably a stand-in for Fort Union, NM), and action takes place at Adobe Walls in the Texas Panhandle. The above plus presence of Comanche and Kiowa war parties indicates the train is moving southwest on the Cimarron Cutoff of the Santa Fe Trail, through the westernmost Oklahoma Panhandle.