Paul III died on November 10, 1549, his last days embittered by dissension with his family, whose advancement had been his chief thought, and for whom he had sacrificed the friendship of the Emperor and the interests of the Church. His last act was to sign an order to place Parma in Ottavio's hands; but the Orsini, who were holding the town, refused compliance.
The Conclave which followed was unusually prolonged. The imperial party, with whom the Farnese party made common cause in the hopes of winning Parma at least, if not Piacenza, for the family, were in a majority, and aimed at the election of Pole or the Cardinal Juan de Toledo, both known to be well disposed towards ecclesiastical reform. But the French party, though not able to elect any of their own candidates, were fully able to prevent the election of any other; and, after the Conclave had lasted more than two months, the two parties agreed to elect the Cardinal del Monte, who took the name of Julius III (February 7, 1550). Although his sympathies on the whole had been French, although he had been associated with the removal of the Council to Bologna, although he had the reputation of frivolity and vice, the imperial party accepted him as likely to choose tranquillity rather than war and intrigue. Tranquillity meant the continued domination of Spain. His good disposition towards the Emperor soon became evident in a number of matters, trifling in themselves, but important in the aggregate. More important still was the intention which he soon announced of reopening the Council at Trent. In fact, on November 14, 1550, he published a Bull summoning the Council to meet at Trent in the following May, notwithstanding the opposition of France, and the impossibility of settling the conditions in accordance with the wishes of the Emperor, the demands of the German Diets, and the interests of the Curia.
Julius had restored Ottavio Farnese to Parma in fulfilment of promises made in the Conclave, but he could not effectually protect him against the hostilities of Gonzaga from Milan. Nor could he persuade Charles to restore to his son-in-law Piacenza also. On the contrary the pressure of Gonzaga on the borders of Parma and his intrigues within the Duchy drove Farnese to apply for aid from France (December, 1550). Terms were arranged with France and Ottavio passed into the service of Henry. The King assembled troops at Mirandola. The Emperor pressed for a sentence of confiscation against Ottavio, and offered a loan to enable Julius to carry it out. Gonzaga seized Brescello (to the north-east of Parma) from the Cardinal d'Esté. The Pope hesitated, but finally decided that it was more dangerous to offend the Emperor, and (May, 1551) declared Ottavio deprived of his fief. It then became necessary to resort to force, and Giambattista del Monte, the Pope's nephew in command of the papal troops, received orders to co-operate with Gonzaga in the occupation of the Parmesan (June).