 In 945 or 946 Bishop Giseprando (943–after 963) added the name of S. Martianus to the list of patrons of the cathedral.The cathedral was severely damaged and pillaged after the siege of Tortona by Frederick Barbarossa in 1155, and again in 1163.The plight of Tortona was made greater due to the firm support of Bishop Oberto for the legitimate Pope Alexander III rather than the Emperor's antipope Victor IV.