The Greatest Swordfight in Modern Times took months of practice.

Reiner decided early on that the film’s epic duel — simply referred to in the book as “The Greatest Swordfight in Modern Times” — would be shot in close-up, meaning Elwes and Patinkin had to become expert fencers in a short amount of time. So Diamond and Anderson would pull the actors aside any time they were not filming to rehearse, roughly dedicating eight hours a day, every day to training.

Finally, after months of practice, shooting began at 8:30 a.m. on Nov. 10. Originally intended to film over the course of a single day, Elwes wrote that, quickly “one day became two. Two days became three. Three then became four. In all, we ended up spending the better part of a week filming The Greatest Swordfight in Modern Times, which I suppose is appropriate.”