The Prince and His Precious Vixen

Wendy has to be married before she turns twenty or she goes to prison. She is living in the body of a girl from a much earlier age, one known for throwing herself at a man who treats her badly, and her own plan had been to drop him and live quietly, until she was told about the deadline. She is a weapons expert from the present day, and she ended up here after an accident. She picks Zeller, the heir of a princely house. He is good-looking and easily embarrassed, and a little teasing turns his face and ears red, so she decides he will do. Then Zeller's household comes under threat, with an army of a hundred thousand at the city walls. Fighting wars is what Wendy is good at, so she builds the most powerful weapons she can and helps him cut down his enemies on every side.