I feel like this would work better as an H manga.
Also, I don't have the contexts, but I'm gonna give my thoughts.
First off, why did he appoint a traumatized civilian as a commander? She doesn't seem that trained and she wants out of her position.
She literally got a bunch of her soldiers killed in her battle.
Secondly, the mc doesn't seem that trained in combat. If the opponent was a little more sneaky, the mc would've just died right then and there.
He seems more suited as a manager, seeing as he somehow knows a whole bunch of things from our world like how to make paper.
Third, why does it seem like the mc only got his position by screwing people in higherup positions?