She was built in the United Kingdom as Monassir, being later Switzerland. On 1928 she was bought by Naviera Pinillos and renamed Duero.
At the beginning of the Civil War she was under republican control, sailing with the camouflaged name of Urbi. At the end of the war she was recovered by her shipowners. On 1943 she struck an underwater mine at the Strait of Gibraltar, but in spite of serious damage she was towed by a Portuguese ship until being beached close to Tangier. Once the water ingresses were plugged she was refloated and towed by the Tormes to Cadiz, where she was repaired. Unfortunately she sank at the same area on 26/July/1953 due to the collision with a British tanker, fortunately without casualties.