Florentines great anxiety, and despairing of preserving their liberty, they sent envoys to King Ruberto of Naples, offering him the dominion of their city; and he, knowing of what immense importance the maintenance of the Guelph cause was to him, accepted it. He agreed with the Florentines to receive from them a yearly tribute of two hundred thousand florins, and he sent his son Carlo to Florence with four thousand horsemen.
Shortly after this the Florentines were relieved in some degree of the pressure of Castruccio’s army, owing to his being compelled to leave his positions before Florence and march on Pisa, in order to suppress a conspiracy that had been raised against him by Benedetto Lanfranchi, one of the first men in Pisa, who could not endure that his fatherland should be under the dominion of the Lucchese. He had formed this conspiracy, intending to seize the citadel, kill the partisans of Castruccio, and drive out the garrison. As, however, in a conspiracy paucity of numbers is essential to secrecy, so for its execution a few are not sufficient, and in seeking more adherents to his conspiracy Lanfranchi encountered a person who revealed the design to Castruccio. This betrayal cannot be passed by without severe reproach to Bonifacio Cerchi and Giovanni Guidi, two Florentine exiles who were suffering their banishment in Pisa. Thereupon Castruccio seized Benedetto and put him to death, and beheaded many other noble citizens, and drove their families into exile. It now appeared to Castruccio that both Pisa and Pistoia were thoroughly disaffected; he employed much thought and energy upon securing his position there, and this gave the Florentines their opportunity to reorganize their army, and to await the coming of Carlo, the son of the King of Naples. When Carlo arrived they decided to lose no more time, and assembled a great army of more than thirty thousand infantry and ten thousand cavalry—having called to their aid every Guelph there was in Italy. They consulted whether they should attack Pistoia or Pisa first, and decided that it would be better to march on the latter—a course, owing to the recent conspiracy, more likely to