“Born on the Fourth of July” is a line by an American composer, but it’s not Sousa: it’s from George M. Cohan’s “The Yankee Doodle Boy“, a.k.a. “(I’m a) Yankee Doodle Dandy”. Maybe Harry’s just trying to push Wally’s buttons by referencing the 1989 Tom Cruise film about the difficulties faced by a returning war vet?