I'd say the Italian and German fascists, and their various European backers, knew precisely what they were for, i.e. fiercely nationalist, harking back to the 'glory that was...', and so on. You can certainly define them by the groups they opposed, i.e. internationalists, socialists, trade unionists, liberals, etc. That they murdered millions of Jewish people as well can never be ignored, but it was part of the overall corruption of their so-called philosophy, rather than its central plank. (Anyway, I think it's a badly phrased essay title...)