At this time the French were again, after the battle of Pavia, driven from Italy, and Clement VII., afraid of the overweening power of Charles V., formed a league against him. The duke of Urbino was chief over the army of the league, and Guicciardini was named lieutenant-general of the pontifical army in the ecclesiastical states. The choice that had been made of the duke of Urbino, as chief leader, was injudicious. He had been driven from his states by Leo X.; Lorenzo de' Medici had been gifted with his duchy, and he naturally was inimical to his rival's family. His irresolute, shuffling conduct during the disastrous advance of the constable Bourbon on Rome, was doubtless a principal cause of the sack of that city. Guicciardini, as general of the papal army, exerted himself in vain to induce him to more energetic measures: instead of throwing himself before the advancing army of the imperialists, he slowly followed it. When Bourbon was in the neighbourhood of Arezzo, the duke of Urbino entered Florence. The power of the Medici was odious in that city. A formidable party, whose watchword was liberty, regarded with triumph the dangers to which Clement VII. was exposed. A number of the younger nobility among them took occasion of the alarm excited, to seize on the palace of government. The duke of Urbino prepared to attack it, but first sent Federigo da Bozzole to treat with the party who held it. Full of enthusiasm and courage, the young men refused all terms, and Bozzole left them, enraged at their obstinacy and their personal ill-treatment of himself. Guicciardini perceived the dangers that threatened his country. It was an easy task for the duke of Urbino to attack the palace of government, to destroy it and all those within; but an act of violence and bloodshed was to be avoided. Guicciardini hastened forward to meet Bozzole as he left the palace, and represented to him briefly how displeasing such a contest would be to the pope, and how detrimental to the confederates; and how much better it would be to calm, instead of exasperating, the mind of the duke of Urbino. Bozzole yielded, and gave hope to the duke that quiet might be restored without recourse being had to arms; pacific means were in consequence resorted to, and the insurgents induced to quit the palace. Guicciardini relates this circumstance and his interference with pride, in the belief that he had done his country as well as the pope good service, but he adds, that he got no thanks from either side; the Medici party accusing him of preferring the lives and safety of the citizens to the firm establishment of that family; while the other party declared that he had exaggerated their difficulties, and caused them needlessly to yield their advantages.