Petilla de Aragón is a town and municipality of the autonomous community of Navarra, northern Spain. The municipality itself is formed by two enclaves (Petilla de Aragón itself and Los Bastanes) that are entirely surrounded by the neighboring autonomous community of Aragón.In the 15th century, Petilla was the site of a battle between the armies of the País Vasco and Aragón in which the fictional troubadour Manrico and the Conte di Luna, of Verdi's Il trovatore, fought on opposite sides, not knowing that they were brothers; this is recounted by the gipsy Azucena in her famous aria Stride la vampa!Notable peopleSantiago Ramón y Cajal (1852–1934) was born here; Petilla terminology, a neurological nomenclature, is named after the town.