'Sixtus IV' (
July 21,
1414 –
August 12,
1484), born 'Francesco
della Rovere', was
Pope from
1471 to
1484. He founded the
Sistine Chapel where the team of artists he brought together introduced the Early
Renaissance to Rome with the first masterpiece of the city's new artistic age (
Michelangelo's frescoes were added in a later phase).
Biography
He was born to a modest family near
Savona,
Liguria,
Italy: the precise town is variously stated to be
Albisola or, more often,
Celle Ligure, a town near
Savona in the
Republic of Genoa. He joined the
Franciscan Order, an unlikely choice for a political career, and his intellectual qualities were revealed while he was studying
philosophy and
theology at the
University of Pavia. He went on to lecture at many eminent Italian universities. He was elected
Minister General of the Franciscan order in
1464. In
1467, he was made a
Cardinal by
Pope Paul II (1464–1471).
With his election to pope, Sixtus IV declared a renewed
crusade against the
Ottoman Turks in
Smyrna. Fund-raising for the crusade was more successful than the half-hearted attempts to storm Smyrna, with little to show in return. Some fruitless attempts were made in unification with the
Greek Church. For the remainder of his pontificate he turned to temporal issues and dynastic considerations. Sixtus continued the dispute with
Louis XI of France (1461–1483), who upheld the
Pragmatic Sanction of Bourges (
1438), according to which papal decrees needed royal assent before they could be promulgated in France. This was a cornerstone of the privileges claimed for the
Gallican Church and could never be shifted as long as Louis XI maneuvered to replace
Ferdinand I of Naples with a French prince, thus being in conflict with the papacy, which as a princely strategist could not permit it.
Like a number of Popes, Sixtus IV adhered to the system of
nepotism. In the fresco by
Melozzo da Forlì he is accompanied by his
Della Rovere and
Riario nephews, not all of whom were made cardinals: the
protonotary apostolic Raffaele Riario (on his right), the future Pope
Julius II (1503–1513) standing before him, and
Girolamo Riario and
Giovanni della Rovere behind the kneeling
Platina, author of the first
humanist history of the Popes. His nephew
Pietro Riario also benefited of his nepotism, becoming one of the richest men in Rome and being entrusted of Sixtus IV's foreign policy, but died prematurely in 1474, his role passing to Raffaele.
The secular fortunes of the Della Rovere began when Sixtus invested his nephew
Giovanni with the ''signoria'' of
Senigallia and arranged his marriage to the daughter of
Federico III da Montefeltro, duke of Urbino; from the union came a line of Della Rovere dukes of Urbino that lasted until the line expired, in 1631.
[1]
In his territorial aggrandizement of the
Papal States Sixtus IV's niece's son Cardinal
Raffaele Riario, for whom the
Palazzo della Cancelleria was constructed, was a leader in the
1478 failed
"Pazzi conspiracy" to assassinate both
Lorenzo de' Medici and his brother and replace them in
Florence with Sixtus IV's other nephew,
Girolamo Riario.
Francesco Salviati,
archbishop of Pisa and a main organizer of the plot, was hanged on the walls of the Florentine
Palazzo della Signoria. To this Sixtus IV replied with an
interdict and two years' of war with Florence. He also encouraged the
Venetians to attack
Ferrara, which he wished to obtain for another nephew. The angered Italian princes allied to force Sixtus IV to make peace, to his great annoyance.
As a temporal prince who constructed stout fortresses in the
Papal States, Sixtus IV committed himself to
Venice's aggression against
Ercole I d'Este,
Duke of Ferrara, inciting the Venetians to attack in
1482 in the so-called
War of Ferrara. Their combined assault was opposed by an alliance of the
Sforzas of
Milan, the
Medicis of
Florence along with the
King of Naples, normally a hereditary ally and champion of the Papacy. For refusing to desist from the very hostilities that he himself had instigated (and for being a dangerous rival to Della Rovere dynastic ambitions in the
Marche), Sixtus IV placed Venice under interdict in
1483.
Sixtus IV consented to the
Spanish Inquisition and issued a
bull in
1478 that established an
Inquisitor in
Seville, under political pressure from
Ferdinand of Aragon, who threatened to withhold military support from his kingdom of
Sicily. Nevertheless, Sixtus IV quarrelled over protocol and prerogatives of jurisdiction, was unhappy with the excesses of the Inquisition and took measures to condemn the most flagrant abuses in 1482. In ecclesiastical affairs, Sixtus IV instituted the feast (December 8) of the
Immaculate Conception of the
Virgin Mary. He formally annulled (1478) the confusedly reformist decrees of the
Council of Constance.
Princely patronage

Pope Sixtus IV appoints Platina as Prefect of the Library, by Melozzo da Forlì
As a civic patron in Rome, even the anti-papal chronicler
Stefano Infessura agreed that Sixtus IV should be admired. The dedicatory inscription in the fresco by
Melozzo da Forlì in the
Vatican Palace records: "You gave your city temples, streets, squares, fortifications, bridges and restored the
Acqua Vergine as far as the
Trevi..." In addition to restoring the aqueduct that provided Rome an alternative to the river water that had made the city famously unhealthy, he restored or rebuilt over 30 of Rome's dilapidated churches, among them San Vitale (
1475) and Santa Maria del Popolo, and added seven new ones. The
Sistine Chapel was sponsored by Sixtus IV, as was the ''Ponte Sisto'', the Sistine Bridge – the first new bridge across the
Tiber since antiquity – and the building of ''Via Sistina'' (later named ''Borgo Sant'Angelo''), a road leading from
Castel Sant'Angelo to Saint Peter. All this was done to facilitate the integration of the
Vatican Hill and
Borgo with the heart of old Rome. This was part of a broader scheme of
urbanization carried out under Sixtus IV, who swept the long-established markets from the
Campidoglio in
1477 and decreed in a bull of
1480 the widening of streets and the first post-Roman paving, the removal of porticoes and other post-classical impediments to free public passage.

Ponte Sisto, the first bridge built at Rome since Antiquity
At the beginning of his papacy in
1471, Sixtus IV donated several historically important Roman sculptures that founded a papal collection of art that would eventually develop into the collections of the
Capitoline Museums. He also refounded, enriched and enlarged the
Vatican Library. He had
Regiomontanus attempt the first sanctioned reorganization of the
Julian calendar and called
Josquin des Prez to Rome for his music.
His bronze funerary monument, now in the basement Treasury of
St. Peter's Basilica, like a giant casket of goldsmith's work, is by
Antonio Pollaiuolo. The top of the casket is a lifelike depiction of the pope lying in state. Around the sides are bas relief panels, depicting with allegorical female figures the arts and sciences (Grammar, Rhetoric, Arithmetic, Geometry, Music, Painting, Astronomy, Philosophy, and Theology). Each figure incorporates the oak tree ("rovere" in Italian) symbol of Sixtus IV. The overall program of these panels, their beauty, complex symbolism, classical references, and arrangement relative to each other is one of the most compelling and comprehesive illustrations of the Renaissance worldview.
In addition to being a patron of the arts, Sixtus IV was a patron of the sciences. Before becoming Pope, spent time at the then very liberal and cosmopolitan
University of Padua, which maintained considerable independence from the Church and had a very international character. As pope, he issued a papal bull allowing local bishops to give the bodies of executed criminals and unidentified corpses to physicians and artists for dissection. It was this access to corpses which allowed the anatomist
Vesalius along with
Titian's pupil
Jan Stephen van Calcar to complete the revolutionary medical/anatomical text
De humani corporis fabrica.
The cardinals of Sixtus IV
At the death of Sixtus IV, the
conclave of cardinals that met to elect his successor numbered thirty-two surviving cardinals, a greater number than at any time since the close of the
twelfth century, excepting perhaps for the multiplied rival cardinalatial colleges of the
Great Schism (1378–1417). Of the thirty-two, only three cardinals survived from before
Pope Paul II: the two nephews of
Pope Calixtus III (1455–1458), Rodrigo and Luis Borgia, and the nephew of
Pope Pius II (1458–1464), Francesco di Nanni Todeschini de' Piccolomini. Six further cardinals survived from the pontificate of Paul II: Thomas Bourchier,
Oliviero Carafa,
Marco Barbo,
Jean Balue,
Giovanni Battista Zeno and
Giovanni Michiel. The remaining twenty-three had been made cardinals by Sixtus IV, and the roster of the princely houses of Italy, France and Spain echoes the chronicles of Renaissance history:
Giuliano della Rovere,
Stefano Nardini,
Pedro Gonsalvez de Mendoza, Giovanni Battista Cybo (later
Pope Innocent VIII),
Giovanni Arcimboldi,
Philibert Hugonet,
Giorgio da Costa,
Charles de Bourbon l'ancien,
Pierre de Foix le jeune,
Girolamo Basso della Rovere,
Gabriele Rangoni,
Pietro Foscari,
Juan of Aragon,
Raffaele Sansoni Riario,
Domenico della Rovere,
Paolo Fregoso,
Giovanni Battista Savelli,
Giovanni Colonna,
Giovanni Conti,
Juan Moles de Margarit,
Giovanni Giacomo Sclafenati,
Giovanni Battista Orsini, and
Ascanio Maria Sforza-Visconti.
Notes
1. On his premature death (1501), Giovanni entrusted his son Francesco Maria to Federico's successor Guidobaldo (Duke of Urbino 1482–1508) who, without an heir, devised the duchy on the boy.
References
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Short Biography
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Genealogy of Leonardo della Rovere, father of Francesco della Rovere, Pope Sixtus IV