Medici, a distinguished Florentine family which attained to sovereign power in the 15th century, owed its earliest distinction to the success with which its members pursued various branches of commerce, and the liberality which they showed in devoting their wealth to the public good. Their well-known arms, representing six balls (from whence their war-cry of 'Palle'), were popularly but without reason believed to represent pills, as their name to show that they had been originally apothecaries. In 1465 Louis XI. of France honoured the Medici by conferring on them the right to wear the French fleur-de-lis on one of the balls. From the beginning of the 13th century the Medici took part in the government of their native republic, and from the period (1378) when Salvestro de' Medici was elected gonfaloniere the family rose rapidly in greatness. It was, however, Giovanni (born 1360) who amassed the immense fortune, and by his generosity and affability gained the position of influence hitherto unparalleled in the republic, to which his sons Cosimo and Lorenzo succeeded. With Cosimo (1389-1464), surnamed Il Vecchio ('the Ancient') and 'Pater Patriæ,' began the glorious epoch of the family; while from his brother Lorenzo was descended the collateral branch of the Medici which in the 16th century obtained absolute rule over Tuscany.
Cosimo's life, except during the brief period when the Albizzi and other rival families succeeded in successfully opposing the Medici influence in the government and exiling him from Florence, was one uninterrupted course of prosperity. He was successful in his political alliances, and procured for Florence security abroad and peace from civil dissensions within her walls. He employed his great wealth in encouraging art and literature. He made Florence the most brilliant centre of the revival of classic learning which distinguishes the 15th century, he enriched her with splendid buildings, and gave unrivalled treasures to the great libraries which he founded. Although his all-powerful influence was not explicitly recognised in the state, and the form of government remained republican, Cosimo in reality was entirely master of the town, and filled the public offices with his partisans. He was succeeded by his son Pietro I., surnamed Il Gottoso ('Gouty'), who, feeble in health and in character, was assisted in the government by the precocious talents of his son Lorenzo (1448-92), afterwards famous in history as Lorenzo il Magnifico.
On his father's death (1469) Lorenzo and his brother Giuliano were recognised as 'principi dello stato.' The growing power of the Medici had roused much envy amongst other great Florentine families; and in 1478 these malcontents, headed by the Pazzi and in league with the pope, Sixtus IV. (Della Rovere), who saw in the Medici a powerful obstacle to his schemes of temporal aggrandisement, formed a plot to overthrow their power, known as the conspiracy of the Pazzi. Only Giuliano was victim of the assassins who were to have killed both brothers during service in the cathedral, and the popularity of Lorenzo was increased by the courage and judgment shown by him in this crisis. Lorenzo was a worthy descendant of his famous grandfather, just in his government, magnanimous to his enemies, and not only a munificent patron of art and literature, but himself a man of wide culture and a distinguished lyric poet. To enlarge on the institutions, universities, and schools founded by him, and on the famous names of painters, sculptors, architects, philosophers, and poets who surrounded him would be to write the history of the Renaissance. He was one of the most zealous promoters of the art of printing, and established under Cennini a printing-press in Florence. Although he used his power in the state well, yet he sapped the existing forms of government; and, in seeking only the advancement of his family to more absolute power, he left Florence at his death weakened and ready to be the prey of her enemies during the troubled times which began with the 16th century.
Lorenzo left three sons, Pietro, Giuliano, and Giovanni. His eldest son, Pietro II. (born 1471), possessed neither capacity nor prudence, and showed himself treacherous alike to friend and foe. He allied himself with the king of Naples against Lodovico Sforza of Milan, and the latter in 1492 called to his aid Charles VIII. of France and his army (see ITALY). Pietro, terrified at the advance of the powerful invader, hastened to meet the French troops on their entrance into the Florentine dominions, and surrendered to them Pisa and Leghorn. The magistrates and people, incensed at his cowardice and treachery, drove him from Florence and declared the Medici traitors and rebels, and deposed them from participation in the government. Pietro was drowned (1503) in the Garigliano, near Gaeta, having joined the French army in their attempted conquest of the kingdom of Naples. All efforts of the Medici to regain their power in Florence were vain until in 1512 the pope, Julius II., consented to send the Spanish army to invade Tuscany. Prato, near Florence, was taken and sacked, and the Florentines, helpless and terrified, drove out their gonfaloniere, Piero Soderini, and recalled the Medici, headed by Giuliano II. (born 1478). In 1513 the elevation of Giovanni de' Medici to the papal chair under the name of Leo X. (q.v.) completed the restoration of the family to all their former splendour and reduced Florence to a papal dependency. Giuliano II. at the pope's desire surrendered the government to Lorenzo II., son of his elder brother Pietro II. Giuliano, created Duke of Nemours on his marriage with a relative of Francis I. of France, died in 1516. The young Lorenzo II., born 1492, and the last legitimate male descendant of Cosimo 'Pater Patriæ,' on whom the pope had also conferred the duchy of Urbino, was feeble, arrogant, and licentious. He died in 1519 leaving only one legitimate child, a daughter, Catharine (q.v.), afterwards wife of Henry II. of France, who played a conspicuous rôle as regent during her son's minority. An illegitimate son, Alexander, born 1510, was afterwards duke.
The power now passed into the hands of the Cardinal Giulio de' Medici, a natural son of the elder Giuliano, assassinated in the conspiracy of the Pazzi; and Giulio was created pope in 1523 under the name of Clement VII. During the invasion of Italy by the Emperor Charles V. in 1527, and the consequent weakening of the papal power, Florence rebelled against the regents imposed on her by the pope, and expelled them along with the young Prince Alexander. The pope and emperor, however, soon made peace, and their united forces were directed against Florence, which, during the famous siege lasting ten months, made her last desperate and unsuccessful stand for liberty. After the surrender of the town, August 1530, Alexander de' Medici was proclaimed hereditary Duke of Florence. His reign was one of unparalleled license and tyranny. He was assassinated in 1537 by his cousin Lorenzino, a descendant of the collateral branch which had its origin in Lorenzo, brother of Cosimo 'Pater Patriæ.' To this younger branch belonged also the next ruler of Florence, Cosimo I. (born 1519). He was son of the famous captain of free-lances, Giovanni delle Bande Nere ('of the Black Bands'). Cosimo, sometimes called the Great, possessed the astuteness of character, the love of art and literature, but not the frank and generous spirit of his greater predecessors. He was cruel and relentless in his enmities, but a just ruler. He extended his territories, and in 1570 was created Grand-duke of Tuscany, and crowned by Pope Pius V. He died in 1574, and was succeeded by his son Francesco I. (born 1541). This duke possessed few of his father's abilities and many of his faults. He became a tool in the hands of his mistress, the unscrupulous Bianca Cappello, whom he married in 1578. The almost simultaneous death of Francesco and Bianca (October 1587) raised suspicions that they had been poisoned by the duke's brother and heir, the Cardinal Ferdinando. Maria, daughter of Francesco I., became the second wife of Henry IV. of France. Ferdinando I. and his son Cosimo II. were popular, and contributed to the prosperity of their country. But at the beginning of the 17th century the race rapidly degenerated; and, after several of its representatives had suffered themselves to become mere puppets in the hands of Austria or Spain, the family became extinct in 1737 at the death of its last male representative, Gian Gastone, the seventh grand-duke. His only sister, the Electress Palatine, the last of all the Medici, expired in 1743.
See, besides the works cited at FLORENCE, Roscoe's two works on Lorenzo and Leo X.; Reumont's monograph (trans. 1876); and a work by E. Armstrong (1896).