When I look for the origin of this phrase, all I get are claims that it’s from old western movies, but nobody ever givens an actual cite. I’m not a big fan of westerns, but I don’t recall anyone ever saying this in a western. (Unless you count Blazing Saddles, but it was already a cliche by then, and that’s the reason they used it there, as the script makes clear. That’s also why Telly Savalas as Ernst Stavro Blofeld says “We’ll head him off at the precipice” in the James Bond film On Her Majesty’s Secret Service. For that line alone Blofeld deserves to die.)
Did anyone ever say this is a western movie?
A search online reveals one claim for its use in a western, by Tim McCoy as “Trigger” Tim Rand in the 1940 movie Arizona Gangbusters, but I can’t find corroboration for this, and have never seen the film myself. The same discussion board claims that William Boyd (playing “Hopalong Cassidy”) must have said it in one of his films, which is a pretty weak claim.
https://groups.google.com/g/rec.arts.movies.past-films/c/m3Ig5gRRbjU?pli=1
Anybody got anything better?
(The phrase makes sense, of course. If you want to set an ambush for someone, you go for the one place you’ll know they have to be. If a narrow pass is the only or by far the shortest way through, you can bet the party you want will be there. By that logic, the stand of the 300 Spartans at Thermopylae is one of the places where this cliche would have been appropriate. But I can’t picture Leonidas saying “We’ll head the Spartans off at the Pass!” about the situation.).