The 1565–66 papal conclave (20 December – 7 January) was convened on the death of Pope Pius IV and ended in the election of Pope Pius V.
Background
Cardinal Vitellozzo Vitelli was Camerlengo; Cardinal Francesco Pisani, the most senior of the cardinals was Dean of the Sacred College. The conclave was made up of several small groups aligned either by family relations, such as those who favored Francesco Gonzaga; and by locale, such as the Florentines. A separate division lay between some of the younger cardinals eager to press the reforms of the Council of Trent, and their senior colleagues whose views of reform leaned towards the Inquisition, which use appeared sometimes to border on the political.[1]
The various factions presented a difficulty for anyone trying to put together a two-thirds majority. Cardinal Farnese had the largest number of commitments, but not the thirty-five needed to elect.[2]Cardinal Borromeo advised Farnese that while he couldn't agree to support him as a candidate, he was willing to work with him to select someone agreeable. Farnese suggested four names, including that of Michele Ghislieri. Ghislieri was also acceptable to the Spanish. (At the emperor's request, Cosimo III of Florence was active behind the scenes, hoping to secure the title of Duke of Tuscany.)[3] Within two hours, they had sufficient votes to elect Ghislieri.
^Setton, Kenneth M., The Papacy and the Levant, 1204-1571 Volume IV. The Sixteenth Century (Philadelphia: American Philosophical Society 1984), p. 885.