On May 17, 1885 Geronimo and a band of other Apaches escaped into Mexico from the San Carlos Reservation northeast of Tucson.

In the story… John Farrington belongs to the 4th Cavalry and is part of a unit sent to find the renegades.

Geronimo is on horseback at the center of the band
Photo taken March 27, 1886, in the Sierra Madre mountains of Mexico

Over a year later, Geronimo surrendered: