Sixtus, the name of five popes, of whom the following are the most important.

I. Sixtus IV. (Francesco D'Albescola Della Ro-Vere)

Sixtus IV. (Francesco D'Albescola Della Ro-Vere), born at Celle, near Savona, July 21, 1414, died in Rome, Aug. 13, 1484. He was a Franciscan monk and a protege of Cardinal Bessarion, taught philosophy and theology in the principal schools of Italy, and was chosen general of his order in 1464. He was created cardinal Sept. 18, 1467, and was elected pope Aug. 9, 1471. The efforts which he immediately made to reform the religious orders and general church discipline were thwarted by his endeavor to unite all Christian princes in a crusade against the Turks, for which purpose he vainly tried to reconcile Louis XI. of France and Duke Charles the Bold of Burgundy. He levied tithes on all church property in Christendom to equip a fleet, which, with contingents from Venice and Naples, only succeeded in capturing Smyrna. Louis XL promised assistance in return for an extension of the royal power over benefices and all church revenues, and the abolition of ecclesiastical courts and immunities; but on these points Sixtus refused to yield. He has been justly reproached, however, with a too great facility in granting favors, and an excessive nepotism.

To secure the cooperation of the Spanish and Austrian princes against the Turks, he sanctioned the nomination to the see of Saragossa of a child six years old, an illegitimate son of the house of Aragon; and he raised successively to the cardinalate five of his own nephews. Two of these cardinals, Riario and San Giorgio, were implicated in the conspiracy of the Pazzi in 1478, which caused the pope to be solemnly arraigned by the Florentine clergy as privy to the intended murder of Lorenzo de' Medici and the death of his brother Giuliano. The Florentine magistrates having hanged Archbishop Salviati of Pisa, one of the conspirators, they were excommunicated, and the city was laid under interdict. The republic was sustained by France, Venice, and the duke of Milan; the other Italian sovereigns sided with the pope, and the quarrel ended in 1480. About the same time Sixtus became involved in a war with Ercole d'Este, duke of Ferrara, whom he wished to dispossess in favor of one of his own nephews. He was backed by the Venetians; but the duke of Ferrara being supported by the king of Naples and the emperor, Sixtus was forced to yield in 1484. During these troubles the Turks besieged Rhodes and ravaged the southern coast of Italy, capturing the city of Otranto and massacring 12,000 of the inhabitants.

The pope once more attempted in vain to organize a crusade, but succeeded in driving off the invaders. Among the other acts of his pontificate were the confirmation of the religious order of Minims, May 23, 1474; the bull sanctioning the Spanish inquisition, 1478; the canonization of St. Bonaventura, April 14,1482; the construction, among many other splendid public works, of the Sistine chapel in the Vatican; large additions to the Vatican library; and the sending of the first missionaries to the Canary islands. The Reguloe Cancellaroe Romance are attributed to this pope. He also left several Latin treatises, among which are De Sanguine Christi (fob, Rome, 1473), De Potentia Dei (fob), and several letters.

II. Sixtus V. (Felice Perretti)

Sixtus V. (Felice Perretti), born at Grotte-a-Mare, near Montal-to, Dec. 15, 1521, died in Rome, Aug. 27, 1590. He was a Franciscan, and distinguished himself as a lecturer on ecclesiastical law at Rimini in 1544 and Siena in 1546, as a popular preacher, and as an author by works on mystical theology and on the philosophy of Aristotle. In 1557 he became inquisitor general at Venice, and in 1570 he was created cardinal, when he assumed the name Montalto. He was elected pope by an almost unanimous vote, April 24, 1585. Both as pope and as secular prince he was distinguished for prudence, severity, and energy. He destroyed the power of the banditti and restored order and safety throughout his territory, administered law with the utmost impartiality and with an appalling rigor, built a great aqueduct, enlarged the library of the Vatican, and in many other ways encouraged industry. He fixed the number of cardinals at 70, required the Catholic bishops of all countries to visit Rome at certain intervals, and reorganized the entire administration of ecclesiastical affairs by the appointment of 15 congregations of cardinals and other officers, He founded a new university at Fermo, and new colleges at Rome and Bologna. From the printing press of the Vatican he published the revised edition of the Vulgate, which had been ordered by the council of Trent. He avoided war with the Christian princes as much as possible, though he encouraged and supported Henry III. against the Huguenots, Philip II. against England, and Archduke Maximilian when he was a candidate for the crown of Poland. He hurled his anathemas against the young king of Navarre, and against Elizabeth of England for putting to death Mary Stuart; and he summoned Henry III. to Rome for ordering the assassination of the duke of Guise. He left a vast treasure in the castle of Sant' Angelo, to be used by his successors only in circumstances strictly defined.

His biography by Leti (Vit'a di Sisto V., Lausanne, 1669) is considered untrustworthy, and that by Tempesti (Storia della vita e geste di Sisto V., Rome, 1754) too partisan. - See J. A. von Hubner, Sixte Quint, sa vie et son siecle (2 vols., Paris, 1871; English translation by Jerningham, London, 1872; German, 2 vols., Leipsic, 1874).