Ooops...........wrong Dennis!  I had Weaver's face in my mind, but Hopper came out on the keyboard.

I should have said that Duel is the film that is generally considered to be Spielberg's directorial debut.  Prior to that, he had directed some shorts and TV episodes.  Technically, his first movie  was a Sci-Fi flick he filmed at the age of 17 [on a budget of $500, using mainly his high-school friends] but it was only shown in a local cinema.  He remembers making a $1 profit on that venture, and from then on he was hooked! 

Phil