Theoden was certainly fey, or seemed so, as the Riders charged towards the enemy. I would imagine that those following him were similarly "charged" (*groan*). It seems to have been the way of the Rohirrim in battle.
In the book, the coming morning seems to have played its part in inspiring the fear in the Orcish army. I cannot recall whether this was a feature of the film (although the rising sun and Gandalf's dazzling brightness was portrayed as the reason for the Uruks failing to hold firm as Helm's Deep).
Well, we'll just have to agree to disagree on this one,
davem. I think that it's a wonderful moment in the film and it brought (and still brings) tears to my eyes. Enchanting, even. But if you want to bring your book-reading, tactically aware "baggage" to the film, then so be it.
