"Un voluntario realista" by Benito Pérez Galdós is a historical novel written and published in 1878. Set entirely in rural Catalonia, the story follows Pepet Armengol, a submissive boy who serves as a convent sacristan, and Sor Teodora de Aransis, a beautiful nun with fanatical views on war and religion. The novel depicts Pepet's transformation from devoted church servant to fierce royalist volunteer during the War of the Agraviados, a brief but significant 1827 uprising that Galdós describes as "repugnant and obscure" yet crucial for understanding Spain's subsequent civil conflicts. (This is an automatically generated summary.)