Gregory began to think he should give still greater weight to the anathemas which he launched against the emperor if they were sanctioned by a council. In the year 1241 he convoked at Rome all the prelates of Christendom. Frederick, who had been established at Pisa since the autumn of the year 1239, exerted himself to prevent the meeting of a council which he dreaded. While the two other maritime republics had declared for the Guelfs, Pisa was entirely of the Ghibelline party. The people were enthusiastically attached to the emperor; and among the nobles, a few only, proprietors of fiefs in Sardinia, headed by the Visconti of Gallura, had forsaken him for the Guelfs. The Pisans, further excited by their jealousy of the Genoese, promised Frederick that they would brave for him all the thunders of the church, and assured him they knew well how to hinder the meeting of the council. A considerable number of French prelates had embarked at Nice for Ostia, on board Genoese galleys. Ugolino Buzzacherino de Sismondi, admiral of the Pisans, lay in wait with a powerful fleet before Meloria, attacked them on the 3rd of May, 1241, sunk three vessels, took nineteen, and made prisoners all the French prelates who were to join the council at Pisa. The republic loaded them with chains, but they were chains made of silver, and imprisoned them in the chapter house of the cathedral. Gregory, alarmed at this reverse of fortune, survived only a few months; he died the 21st of August, 1241; and the college of cardinals, reduced to a very small number, passed nearly two years before they could agree on a new choice. At last, on the 24th of June, 1243, Senibaldi de’ Fieschi, of Genoa, who took the name of Innocent IV, was elected to the chair of St. Peter. His family, powerful in Genoa and in the Ligurian Mountains, was also allied to many noble families, who possessed castles on the northern side of the Apennines; and this position gave him great influence in the neighbouring cities of Placentia, Parma, Reggio, and Modena. The elevation of a Fieschi to the pontificate gave courage to the Guelf party in all these cities. [Sidenote: [1243-1245 A.D.]]