GUICCIARDPNI, FRANCESCO, born at Florence, in 1482, of a noble family, distinguished himself early in the study of the law, of which science he was made professor in his native city. In 1512 he was sent by his countrymen aa ambassador to Ferdinand of Aragon, whose arms had become formidable in Italy. Guicciardini appears to have fulfilled his mission in such a manner as to establish a high opinion of his diplomatic abilities. In the following year he was sent on a mission to Leo X., who, being pleased with him, took him into his service, employed him in various important affairs, and finally appointed him governor of Modena, and afterwards of Parma, both which countries were then in the possession of the pope. After the death of Leo, and the abort pontificate of Adrian VL, Clement VII., who succeeded to tho papal chair, retained Guicciardini in his service, and trusted implicitly to him as his chief adviser, especially on the affairs of Florence. After the surrender of that city to the imperial and papal arms, in 1530, Guicciardini, as the agent of the pope and the Medici, had a considerable share in the changes that took place in the government of the republic; and he is reproached with having advised the proscription of the popular leaders. Afterwards he and the other adherents of the Medici resorted to the old expedient used in turns by the various factions, of calling together a parliament, or geneml assembly of the people, in the great square, which assembly voted the appointment of a belie, or dictatorial commission, which appointed a senate of forty-eight members, and this senate in its turn appointed all the subordinate magistrates, both administrative and judicial. It also established a commission of twelve, with the name of reformers of the state.' Tho members of this commission wero chosen from among the adherents of the Medici, and Guicciardini was one, and the most infiuental of the number. The twelve began by abolishing the old authorities of the republic, tho Gonfalouicre and the Priori, and proclaiming Alessandro de' Medici duke of Florence. The new duke had a foreign guard at tho public palace, or town-hall, where he fixed his residence, and he began building a citadel to overawe the people. Filippo Stroazi, one of the twelve, who afterwards became the leader of the disaffected, furnished him with money to complete the work. Strozzi and others being soon disgusted at the haughtiness and licentiousness of the duke, left Florence and went to Naples to lay their complaints before the emperor Charles V., who had been a party to the capitulation of 1530, by which the liberties of Florence were guaranteed. The Duke Alessandro also repaired thither with Guicciardini, who had remained attached to him, and when the emperor communicated to him the accusations of the refugees, and asked for his reply, the duko entrusted Guicciardiui with his defence.
Guicciardini's answer was sophistically though cleverly written. He contended that the changes made in the government of Florence had been effected by the parliament, or sovereign assembly of the people, according to the old practice of the republic, and at the instigation of those very refugees, Strozzi, Valori, Salviati, Ridolfi, and others, whose ambition not being satisfied, because the duke did not choose to give all his authority into their hands, made them now assume the language of popular discontent. But he slurred over the serious charges of cruelty, licentiousness, and other abuses of power, which were sub stantiated against the duke. The emperor, engrossed by his numerous state affairs, dismissed the Florentine question by stipulating with the duke that the refugees should have a full amnesty, and be allowed to return to Florence, and be restored to their property. He tried at the same time to make the duke acknowledge himself his feudatory : but Guicciardini prevented this, for although hostile to a popular form of government, he was anxious to maintain the political inde pendence of his country under a native ruler. When the Duke Ales sandro was murdered by his cousin and companion in debauch, Lorenzino de' Medici, in January 1537, Guicciardini by his timely measures prevented a popular explosion, and by his influence in the council obtained the appointment of Cosmo de Medici as governor of the Florentine republic, with a fixed Income of 12,000 golden florins a-year, and under the express condition that he should do nothing without the advice of his council. Here however Guicciardini miscal culated, and ho was told so at the time by his brother-councillor Vettori : he wished to establish something like the government of Genoa or Venice ; but the circumstances of those states were very different from those of Florence, where the Medici had been for a century past the hereditary leaders of a powerful party, and were sup ported by foreign powers. The event soon undeceived Guicciardini. Cosmo, aspiring, and clever, with more self-command than his prede cessor Alessandro, soon exchanged his title of governor for that of duke, and established himself as absolute lord not only of Florence, but of all Tuscany. [Cosmo Guicciardini remained for some time attached to him ; but finding his advice disregarded, he resigned his office, and withdrew to his country-house at Arcetri, where he employed himself in writing the contemporary history of Italy, which was not published till more than twenty years after his death. He died in his retirement, in May 1540, at the age of 58, and his death was said to have been hastened by disappointment at the untoward result of his political exertions.