Lady of Blossholme-H. Rider Haggard

Set during the Tudor period of English history, When Knighthood Was in Flower tells the tribulations of Mary Tudor, a younger sister of Henry VIII of England who has fallen in love with a commoner. However, for political reasons, King Henry has arranged for her to wed King Louis XII of France and demands his sister put the House of Tudor first, threatening, "You will marry France and I will give you a wedding present – Charles Brandon's head!" (Summary adapted from Wikipedia)