La critique de Roger Ebert
Howard Hawks' "Rio Lobo" is a John Wayne Western. That was a little unusual in 1970, because John Wayne had unaccountably been finding himself in some Westerns that weren't John Wayne Westerns. "Chisum" and "The Undefeated" (1969), for example, didn't quite understand the mythic nature of the Wayne character, and so we got a lot of scenery and very little chemistry. "True Grit" (1969), a very good movie, chose to comment on the Wayne character instead of exploiting it. And so it has been a long time since a John Wayne Western in the classic mold: Not, in fact, since Howard Hawks' last film, "El Dorado" (1967).
Both "El Dorado" and "Rio Lobo" deliberately avoided any innovations in the basic Wayne role, as it was invented and shaped since the 1930s by John Ford, Henry Hathaway, Hawks himself, and minor directors who copied them. Hawks apparently felt that he'd already had his day an an inventor of archetypes, and now that he was in his '70s (and Wayne was in his '60s), it was time to mine the vast deposits of memories, conventions and nostalgia from all those earlier Wayne films.
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In this case, the story itself doesn't matter much. We go to a classic John Wayne Western not to see anything new, but to see the old done again, done well, so that we can sink into the genre and feel confident we won't be betrayed. To some degree Wayne movies are rituals, and so it is fitting that they resemble each other. "El Dorado" was a remake of Hawks' "Rio Bravo" (1958), and "Rio Lobo" draws from both of them. (It is said that when Hawks called Wayne and offered to send over the script, Wayne replied, "Why bother? I've already made the movie twice.")