George Stevens was originally slated to direct but bowed out because of script problems. His replacement, Robert Mulligan, had directed Gregory Peck to an Oscar in Du silence et des ombres... (1962).
A casting director for Pakula-Mulligan Productions discovered Peck's young co-star, 11-year-old Apache Indian Noland Clay, on the White River Reservation in Arizona. Clay was one of several Apache boys who were flown to Los Angeles, CA, for screen testing. The estimate for his salary was at least $1,000 per week. As part of his salary, a trust fund was established for Clay's education. National General also promised funds to improve a recreation center on the White River Reservation, and the company made a donation in the reservation's name to the Save the Children Federation.
Clay was also the focus of a seven-minute short film, shot by photographer Dennis Stock, which featured behind-the-scenes footage, and was offered to national television outlets as a promotional item.
In Les grands espaces (1958)--starring and produced by Gregory Peck -the foreman (played by Charlton Heston) Steve Leech rides a very striking and beautiful black and white paint horse. Ten years later in this film--also starring Peck--the same horse is ridden by the Apache chief Salvaje, played by Nathaniel Narcisco.
After Patricia Neal recovered from her stroke, she had a choice of either this film or Trois étrangers (1968) as her comeback vehicle. Although she opted for the latter, she said she would like to have done this film also.
Although this was Gregory Peck's only film in 1968, he should also have appeared in the Mirisch production "The Bells of Hell Go Ting-a-Ling-a-Ling." Scripted by Roald Dahl, this production was shut down after just six weeks shooting due to "poor weather conditions", a popular euphemism for a troubled shoot.