Books: The Tyranny of the Night, Lord of the Silent Kingdom
Author: Glen Cook
Purchase: Book 1 , Book 2
Glen Cook uses his unparalleled world building skills to showcase a version of Crusades era western Europe where magic exists and the gods are all too real. Else Tage, slave soldier turned infiltrator, represents a threat in the mind of hoary powers, sorcerers and warrior emperors, even if he isn't aware of it. A heresy rages, a crusade stutters and stumbles and the old gods rise.
The mix of complexity, politics, war and realism that Cook creates is a pretty unique blend. There are dozens of non fantasy war authors who would kill their kids to achieve a similar level of grit and grime in their work, but Cook will never achieve the same level of commercial success because A) he writes fantasy and B) as far as I can tell, he is an ornery cuss.
The heresy in the books is a pretty accurate representation of the Albigensian heresy in the south of France, which the Catholic Church put down in typically brutal fashion - the contention was that, as the world is such a shitty place to live, it seems more reasonable to assume it was made by the Devil than God. Cook even gets some of the famous lines of the era into the lips of his characters.
For readers of:
Glen Cook, Robert Jordan, David Eddings, Pat Rothfuss, Joe Abercrombie, Steven Erikson