Echo of the High Kings - epic fantasy by Kal Sprigg

Echo of the High Kings was written while I was deployed to Afghanistan with the US Army.  I spent a lot of time working out not just the magic system, but the cultures, economics, and history of the world and how it applied to the characters and their actions.  I think that the world-building pays off in that the characters are products of their world, a world where science and mathematics is as much a part of the world as dragons, god, and demons.