So I looked at it. I liked the idea of the incompetent wizard. That's very Diskworld. But then just as I'm staring to like the guy, the next chapter has the farm wife staying indoors. You lose me there, because I worked on a farm. Farm wives don't stay indoors, and certainly would not have in a pre-industrial world. There's too much work to do. Monsters coming out of the ground, okay, but who runs toward the monster to get a better look? A hero would, but we've not yet established that this guy is a hero. And then the girl who doesn't want to be pushed into a forced marriage. In those days most women would have accepted that that's how things are. It takes gumption to oppose customs, and I first need to get to know her as a person before I'll accept that she has that kind of gumption. In each chapter we're told thus-and-such, very briefly, with no background or explanation. I think the chapters are way too short to draw me in, convince me of the situation, and keep my interest. You need to make me care about the characters very early.
I think the first chapter needs to build the world, rather than just dropping me into it, and then if you're going to drop the thread and move on to another sub-plot, that next chapter needs to do the same. Either explain why the farmer has the powers he does, or spend a lot more time building the background so that I can believe it.
Getting back to the first chapter: I want to know how the boy wizard ended up there. Do the generals really expect him to be able to help? Why do they seem to think he can? And if they do really think he can help, why are they so curt with him? Have they given him any preparation? A real general, even back then, I think, would have given him the lay of the land and told him what to expect, if they really expected him to do any good. But why would they even bother with a boy wizard when the other side could be expected to have an experienced wizard? I think the chapter has to explain to us what he's doing there and why the generals have dropped an inexperienced and obviously incompetent boy wizard into a battle with no preparation. Or if they don't expect him to do any good, and they have some other reason for putting him there, we need an inkling of that.