Harry Turtledove 
Prince of the North 

Sometimes, the enlightened thing to do is… FIGHT LIKE A DEMON A younger son, Gerin the Fox has been raised not to lead but to read and study magic. But Fate stepped in, leaving him ruler at a young age. Quaintly, he intends to rule for the welfare and betterment of his people. But many forces combine to make his rule a lively, as well as enlightened, one:His son is kidnapped…Wildmen raid his lands and threaten his boarders…A neighbouring baron with almost as much land as Gerin wants more… And, most menacing of all: Gerin is having prophetic dreams of monsters rampaging over the northlands, with Gerin and his men in desperate, losing struggle to drive them back… As Gerin and his liegemen fight to keep some semblance of civilization in the Northlands, the forces of Chaos conspire to tumble Gerin’s world into a very dark age indeed.