I think Lewis was trying a little too hard in The Last Battle to produce the perfect allegory, and couldn't come up with a compelling story to wrap it with. He

I think Lewis was trying a little too hard in The Last Battle to produce the perfect allegory, and couldn't come up with a compelling story to wrap it with. He was working under much higher expectations than when he first started the series, and getting the "apocalyptic stuff" wrong would have been a surefire way to make a lot of Christians angry. It certainly doesn't help that, by this point, the reader expects an epic battle of Tolkienesque proportions. Instead we are given a talk show adaptation of the Book of Revelations.