does anybody know what is typically found in the war genre of books? o.O

I'm reading "Song of the Dragon" by Tracy Hickman for my study of Fantasy. This is the first novel that I've read with such intense battle scenes, and i don't know if its different from battle found in a traditional war novel. There are different species of beings fighting in this book but I'm interested in the fundamentals of a war novel. in this book the narration is third person with insight into the protagonists mind. There is also a rank system that differs from a traditional one. is rank one of the things ever present in a war book? if so is creating a new system key in making this novel fantasy? Do war novels work in a similar fashion to vampire novels(i.e. vampires have evolved from Bram Stoker's "Dracula" to the objects of lust found in "Twilight")? Does war have to reinvented each time its taken as a subject for writing? Is it the reinventing that makes the book memorable? I'm not looking for answers to each of my questions i just thought i'd throw them out there. i'd greatly appreciate any insight.