Another Bishop Pietro was one of those who in 1241 were made prisoners by Emperor Frederick II at the Battle of Giglio, while on their way to attend a council in Rome called by Pope Gregory IX. Bishop Melchiorre Busseto in 1284 was killed by the followers of William VII, Marquess of Montferrat, for which the Marquess lost all his rights of patronage in the Diocese of Tortona, and was compelled, barefoot and clad in a shirt only, to walk from the scene of the bishop's murder to the cathedral.