I'm Done Guarding

The demon clan sits on the far side of Demonwall Pass and does not cross it. For thirty years that has been down to one man. Julian Cross broke through to the rank of war god at the age of ten, which nobody believed at the time, and he held the pass by himself, killing enough of them that they stopped trying. Thirty years of quiet changes what people think. The Federation's leadership and its citizens come around to the view that the demons have kept the peace because they are decent and want to live alongside humans. The leadership has its own reason for liking that view. Julian's record has grown larger than the men above him, and they want him gone. He is driven out of the pass with the public cursing him. The demons move as soon as he is off the wall. They kill warriors and ordinary people. The Federation works out what it has done and asks him back, but another power has taken him in by then and there is no getting him to return. The people who drove him out are cut down, and the ones left alive are kept as slaves. What they have taken and the run of victories convince the demons that nobody can stop them, and they go after Julian himself.