If you limit the genre to “movies that deal explicitly with combat, or the American presence in Vietnam generally,” you get about two dozen movies (including post-’70s films). Yet, argues Clay Risen, expand those limits somewhat and “the genre spins off into dozens of subcategories, the shape of which say a lot about how America has viewed the war over the decades since it ended.” (Risen includes Rambo, Hair, MAS*H, Bonnie and Clyde, Easy Rider, and even Love Story and Shampoo.)