Valperga, by Mary Shelley (novel)

Valperga: or, the Life and Adventures of Castruccio, Prince of Lucca, is an 1823 historical novel by the Romantic novelist Mary Shelley, set amongst the wars of the Guelphs and Ghibellines (the latter of which she spelled "Ghibeline".) Valperga is a historical novel which relates the adventures of the early fourteenth-century despot Castruccio Castracani, a real historical figure who became the lord of Lucca and conquered Florence. In the novel, his armies threaten the fictional fortress of Valperga, governed by Countess Euthanasia, the woman he loves. He forces her to choose between her feelings for him and political liberty. She chooses the latter and sails off to her death