Galeazzo II became co-ruler of Milan with his brothers Bernabò and Matteo II through a statute forged by the Milanese General Council. During his time as signore, Galeazzo II was focused on increasing the prestige and influence of the Visconti. He forged ties with Holy Roman emperor Charles IV, who granted him and his two brothers, the shared title of imperial vicar. Although Visconti military activities in North Italy allowed Galeazzo II to set up his base of operations in Pavia, it also drew him into conflict with the Papacy. His death on August 4, 1378 allowed his son Gian Galeazzo Visconti to expand the influence of the family as signore.