COSMO I., duke of Florence, and afterwards grand-duke of Tuscany, was the son of Giovanni de Medici, a celebrated condottiere of the 15th century, who was descended in a direct line from Lorenzo, the younger brother of the elder Coamo. This line formed a collateral branch of the first house of Medici, and its members remained iu a private station as wealthy citizens of Florence during the lives of Como, Pietro, Lorenzo the Magnificent, and Leo X., taking little part in the civil broils which agitated the republic under the administration or ininence of tha elder branch. That branch became extinct by the death In 1510 of Lorenzo de 'Medici. duke of Urbino, the only legitimate grandson of Lorenzo the Magnificent, which was followed woo after by the death of his uncle, Pope Leo X. The Duke of Urbino left an illegitimate son, Alessandro, who was made Duke of Florence after the surrender of that city to the allied arms of Charles V. and of Pope Clement VII., In 1530. Alessandro was a proilizate prince, mid after several yaws of tyranny was murdered by his relative Lorenzino, who belonged to the junior branch of the Medici, in 1537. Upon perpetrating thin murder, Lorenxino fled to Venice. The Meads and councillors of the late duke, with Guieciar. dini the historian at their head, proposed to appoint young Cosino, of the younger branch of the Medici, as successor to Alessandro. Coemo had against him a number of emigrants, some of the first families cf Floreuce, who were hostile to the Medici. some through jealousy and rival ambition, and othere because they wished to re-establish the republic. These emigrants were scattered about the eliffereut Italian cities, and were encouraged and supported by Pope Paul Ill., by Count Pepoli of Bologna, and others. They also relied on the protection of Francis L of France, while Cosmo on his aide was protected by the emperor Charles V., who ackuowlodged him as Duke of Florence. The emigrants, having collected a few thousand men. invaded the Florentine territory, but were defeated by the troops of Coins° at Montetuurlo ; and their leaders Albizzi, Valori, and Filippo Strozzi, were taken prisoners and put to death. From that time Coseno reigned absolute lord of Florence. He extinguished ell remains of popular liberty, and he established a system of inquisitorial pollee by means of numerous informers. Persons accused of any designs against the government were tortured, and often put to death. lie had agents also in various parts of Italy to watch the conduct of the Florentine emigrants, and in some instances to get rid of the most dangerous by assassination or poison, as in the case of Lorenzino, who was murdered at Venice by his order, in 1518. He effected a striking change in the simmers of the Florentine people, who were before noted for their garruldy and lightness of convereatien; they became henceforth taciturn and cautious, and spoke in half eentences. In other respects the adminiatnition of Cosmo was orderly and wise ; he was attentive to business, and looked himself into all public affairs Ile had considerable abilities; and If ho rendered Florence and Tuscany entirely dependent on his will, he at the same time sue.
corded by consummate political skill in keeping hie state independent of all foreign powers. Determined to be master at home, he freed his towns from the imperial garrisons, and resisted several attempts at soeroa•Lmcot from the court of Rome. lie was the first to establish the unity and independence of Tuscany as a political state. He formed a native militia of the peassutry, well exercised mid disciplined by experienced officers, so that at three days' notice ho could collect 12.000 men in any particular point, besides the regular regiment., which lie kept in the toeus. Ills finances were in good condition, and Lis treasury always well supplied with money.
Como possessed at first the territories of the two republics of Floreece and Pisa, the latter of which had been conquered by the Florentines before his time. In 1552 lie added to his dominions, by an 'wean/eat with Jacopo d'Appiano, lord of Piombono, that princi pality, end also the island of Elba, when be fortified Porto Ferrejn, and improved its harbour. But a more Important acquisition was that of Siena. That republic had survived the freedom of Floreoce, and had retaioel its independence under tho protection of Charles V. But in 1552 civil factious having broken out among the citizens, who were excited also by the Florentine refugees, they drove away the Spanish garrison and admitted a French auxIliery force. In the fob lowing year Charles V. cent troops to reduce Siena, and Cosmo joined furies to those of the emperor. Not succeeding that year, the emperor withdrew most of his troops; but at the beginning of 1554 Cosecs brought together a larger form, attacked Siena, and Its territory. At the battle of Marciano, in August of that year, the Siennese and their French allies were defeated. After a long and obstinate resistance, In which the women took part, Siena was com pelled by famine to surrender to Camino In April 1555. The conditions I were net harsh. Siena retained her municipal institutions under the protection of the emperor, who was to keep a garrison in it ; but in the meantime Cosmo pieced a garrison In it himself. All those citi• Leos who chum to etnierate were at liberty to do so. A great many availed themeelvm of this stipulation, and retired to the town of Monteleino, where they kept up the semblance of a republic a little longer. Of 40,000 inhabitants which Siena had Kellett+ to the siege, only 6000 remained ; the rest had either died or emigrated. In July 1557, Comm received of Philip II., who had succeeded Charles V., the formal possession of Siena and Its territory, exclusive of the coast near Monte Arrataro, with the pores of Grbitollo, Telamone, Beet(' Stereo°, and Port' Eraola, which remained as a depend.eacy of Spain, and were afterwards annexed to the crown of Naples under the name of 'Sudo Preeldj. The Sienna.o ewer. allegiance to Cosmo, who left to them their municipal laws and magistrates. In August 1559 the small raldne of the Sienna's reptiblie at Montaleino surrendered to Coemo. All Tuscany was now, for the first time since the fall of the Roman empire, nult-d under one government.