One of the most unknown episodes of the Civil War is known as 'La Bolsa de Biels'. In April 1938, the planes of the nationalist bloc bombed the villages of the Sobrarbe (region of Huesca). The majority of its inhabitants started to flee on foot, with children, old people and food on their backs, crossing the mountains until they reached the top of Puerto Viejo, which is one of the natural passages to France, located at almost 2,500 meters of altitude.