What makes the novel a classic

The novel has every requirement one could ask for.... war, dissention, mystery, the hero, the heroine, the love story, a perfect backdrop, sacrifice, and a happy ending..... which is sad all at the same time. We care about the novel's characters, become invested in them, cheer for them, and feel sorry for them. We see the characters grow..... and we're never quite sure how things will turn out.