The cooperation between United States and Mexican military forces in the final phases of the Apache resistance effectively eliminated the tactical advantage that the border had provided.

Lozen moved across this border repeatedly during the resistance years.

Her familiarity with the terrain on both sides of it — with the Sierra Madre mountains of Sonora and Chihuahua as well as the mountains of Arizona and New Mexico — was part of the comprehensive geographic knowledge that made her effective.

The Tres Castillos massacre, which occurred in Mexico, is one of the central events of the story: it was the catastrophe that Lozen was not present for, the event that killed her brother and most of his band while she was separated from them on the mission to protect the pregnant woman.

Her absence from this event — and the accounts’ attribution of significance to that absence — reflect the real military importance of her specific contribution to the band’s survival.