Chicago Reader review:
Sam Peckinpah's notorious western depicted an outlaw gang, made obsolete by encroaching civilization, in its last burst of violent, ambiguous glory. By 1969, when the film was made, the western was experiencing its last burst as well, and in retrospect Peckinpah's film seems a eulogy for the genre (there is even a dispassionate audience—Robert Ryan's watchful Pinkerton man—built into the film). The on-screen carnage established a new level in American movies, but few of the films that followed in its wake could duplicate Peckinpah's depth of feeling. With William Holden, Ernest Borgnine, Edmond O'Brien, Warren Oates, Ben Johnson, Strother Martin, and Albert Dekker; scripted by Walon Green and Peckinpah from a story by Green and Roy N. Sickner, and photographed by Lucien Ballard.
Here (and above) is the trailer.