Walter Scott 
Betrothed 

The Betrothed is the first of two Tales of the Crusaders. The action takes place in the Welsh Marches during the latter part of the reign of Henry II, after 1187. Eveline, the 16-year-old daughter of Sir Raymond Berenger, is rescued from a Welsh siege by the forces of Damian Lacy. She is betrothed to his uncle, Sir Hugo, who leaves on a crusade. Rebels led by Ranald Lacy attempt to kidnap her, and Damian fights them off, but a confused sequence of events convinces the King that she and her beloved are in league against him. (Goodreads)