SIXTUS IV, POPE. — Born at Celle near Savona in 1414 to Leonardo della Rovere and Luchina Monleone, of very modest circumstances. He became a Franciscan friar at a young age, studied at Pavia and Bologna, and completed his studies at Padua, where he obtained a doctorate in theology on 14 April 1444 and later taught philosophy and theology to great acclaim (cf. G. Brotto – G. Zonta, *La Facoltà teologica dell’Università di Padova*, Padua 1922, pp. 170 sq.). He then taught at Bologna, Pavia, Siena, Florence, and Perugia. He subsequently served as procurator of the Order in Rome, vicar general for all Italy, provincial of Liguria, and in 1462 participated in the debate on the Blood of Christ before Pius II. In 1464, he was elected Minister General of the Order at Perugia, and in 1467 presided over the General Chapter in Florence. On 18 September 1467, Paul II created him cardinal of S. Pietro in Vincoli. Upon the death of Paul II, after a conclave lasting only three days, Cardinal della Rovere was elected pope on 9 August 1471, taking the name Sixtus IV, and was crowned on 25 August.
Generous and free in his spending, Sixtus left the papal finances in disarray at his death; but he particularly demonstrated his liberality toward his relatives, who hastened to fill the court, bringing with them many fellow countrymen. Ecclesiastical and civil offices and prebends were widely distributed among them. Of Bartolomeo, the Pope’s brother, was born Leonardo, the “little prefect” of Rome, who soon disappeared; the other brother, Raffaello, had a much larger family: Giuliano, who later became Julius II; Giovanni, who became lord of Sinigaglia and later prefect of Rome; Luchinetta, first married into the Gara family and then into the Francotti; Bartolomeo, a Franciscan friar who later became bishop of Massa and held high offices. The Pope also had two sisters: Bianca, married into the Riario family (q.v.), and Luchina, married into the Basso family, from whom came Girolamo Antonio, a cardinal. In the brief time he lived, it was Cardinal Pietro Riario (d. 5 January 1474) who “held both keys” to the Pope’s heart, while Cardinal Giuliano della Rovere, due to his frequent absences, exercised no predominant influence. Instead, Girolamo, brother of Cardinal Pietro, dominated the scene to such an extent that he could be called the “Ecclesiae imperator”; in 1473, Pietro had secured for him the lordship of Imola and the hand of Caterina Sforza in marriage.
Sixtus IV’s first intention was war against the Turks, who were becoming ever more threatening; he initially thought of convening a council for this purpose, then sent five cardinal legates to the princes of the West on 23 December 1471; thereafter, together with Naples and Venice, he equipped a fleet that operated in the East under Cardinal Oliviero Carafa and later under Archbishop Lorenzo Zane (1472–73).
Paul II’s policy had been to maintain peace in Italy by overcoming the ambitions and jealousies of the princes and to keep Rome tranquil amid the ever-renewed discord. Sixtus IV, at first, aligned himself with Naples and Siena (1476) in the face of the Milan–Venice–Florence alliance, which led to the Pazzi conspiracy against Lorenzo de’ Medici, fostered by Girolamo Riario (26 April 1478), the excommunication of Lorenzo, and the
SIXTUS IV, POPE — Gabriele Zerbi presents to Sixtus IV his *Quaestiones Metaphysicae*. Miniature adorning the dedicatory copy printed on parchment in Bologna by Giov. Valbocchi and Endrico van Haarlem, 1 December 1482 — Vatican Library, memb. II, 19.
pp. 119–29, 152–56; R. Valentini – G. Zucchetti, *Codice topografico della città di Roma*, II, ibid. 1942, pp. 22, 63; M. Combet-Farnoux, s.V. in *DACL*, XV, cols. 1501–15.