De Oñate a La Granja is a historical novel by Benito Pérez Galdós, first published in 1888. It is the third novel in the third series of his Episodios Nacionales, and is set during the First Carlist War (1833-1840). The novel follows the adventures of Fernando Calpena and Don Pedro Hillo, two Liberal prisoners of war who are held captive in a Carlist prison. While in prison, they receive letters from a mysterious woman who promises to help them escape if they agree to do something for her. The novel explores themes of political intrigue, espionage, war, and adventure.