Caught between Hollywood's traditional western genre and the revisionist western styles of the late 1960s and 1970s, Duel at Diablo seems both a little behind and ahead of its time. As an old-fashioned western, Duel at Diablo has traditional cavalry vs. Indian story line and well-executed, exciting battle scenes. Beyond this, the film also addresses racism and oppression towards native Americans in a complex and non-sentimental manner, through various inter-linked sub-plots. While the Apaches may be cruel and the instigators of attacks, it is clear that this is only because they have been oppressed to the point where they have no other resort. This is not a battle between "good guys" and "bad guys" and in the end nobody wins. Perhaps, the film could have delved a little deeper into the social and ethical issues it raises. At times, it appears that the movie itself is unsure whether it is primarily an action film or a message film. However, this is also the movie's strength as its messages do not detract from the story and action, and never appear simplistic or preachy as is often the case in westerns that take a sympathetic perspective on the plight of native Americans.
Meanwhile, the excellent, rhythmic and moody musical score by Neil Hefti, while unusual for a western, is well suited to accompanying the unrelenting action sequences and conveying the tragedy and doom of a society and individuals caught in a vicious cycle of conflict and racism. The casting of the film further contributes to making Duel a Diablo a strong, atypical western. James Garner, who up to then had always played amiable leading men, sheds his typical persona to effectively portray a tough and rugged frontier scout, bent on avenging the murder of his Indian wife. Equally effective and very cool-looking in a 3-piece suit, Sidney Poitier is an army sergeant turned businessman, whose color is on the surface only incidental to the story beyond a couple of subtle inuendos (that said, it is really left to the viewer's interpretation whether his race is significant to the story, and it is somewhat ironic to see a black man taking charge among a regiment of white soldiers in shoot-outs against Indians). Europeans Bibi Anderson and Bill Travers also seem strangely out of place, respectively portraying what could be a Scandinivian emigrant and a Scottish-born American officer. And Dennis Weaver, who up to that time was mainly known as a simple good guy in TV's Gunsmoke plays the part of a nuanced villain. Add to this the beautiful cinematography of wide desert landscapes, and Duel at Diablo is a superior, exciting, and socially-conscious western, not a great one, but certainly unique.
