The great expansion in the Mediterranean and the prominence of the merchant class urged a modification in the city's institutes. The system with consuls was abandoned, and in 1230, the new city rulers named a "capitano del popolo" ("people's chieftain") as civil and military leader. Despite these reforms, the conquered lands and the city itself were harassed by the rivalry between the two families of Della Gherardesca and Visconti. In 1237 the archbishop and the Emperor Frederick II intervened to reconcile the two rivals, but the strains continued. In 1254, the people rebelled and imposed 12 ("People's Elders") as their political representatives in the commune. They also supplemented the legislative councils, formed of noblemen, with new People's Councils, composed by the main guilds and by the chiefs of the People's Companies. These had the power to ratify the laws of the Major General Council and the Senate.