Pope Calixtus III

Pope Calixtus III
December 31, 1378 – August 6, 1458

On December 31, 1378, Pope Calixtus III was born Alonso Borgia in Jativa, Aragon (Spain). The Borgias were an aristocratic family that had gained prestige during the reign of King James I. In 1240, Alonso’s ancestor, Esteban de Borja, had played a role in expelling the Muslims in Valencia. In gratitude, James ennobled the Borgia family. By the time Alonso’s parents, Domingo and Francina, welcomed him into the world, the Bogias had established themselves as a prestigious and respected family.

In 1392, Alonso was sent to Catalan university to study church law at Lerida. While in school, the 14-year-old proved himself to be a brilliant student who excelled in his studies. Alonso’s academic achievements would attract the attention of the Spanish Pope Benedict XIII. Benedict acted as a mentor to Alonso and helped advance his career in the church. In 1408, the pope made Alonso the accessor of a diose, which he performed well. In recognition of his talents, Benedict promoted Alonso to the canon of a cathedral in 1411.

Alfonso V of Aragon

As Alonso gained a reputation for his abilities, King Alfonso V of Aragon began to notice him. In 1417, Alonso visited Alfonso’s court to discuss financial matters. During his stay, Alonso impressed the king so much that he became a royal secretary. During his reign, Alfonso sought to claim the throne of Naples in Italy. However, he needed papal support. When Pope Benedict XIII came into conflict with a rival pope, Martin V, during the Western Schism, Alonso advised the king to switch his support to Martin.

Alfonso V of Aragon
Alfonso V of Aragon

Alfonso V took Alonso’s advice and granted him new church offices in return. In 1420, the king would depart Aragon to press his claim to Naples. In his absence, Alonso became the vice-chancellor of a regency council. Although Alfonso’s campaign ultimately failed in 1423, Alonso would maintain a high position in the king’s government. He went on to act as Alfonso’s trusted advisor and representative.

Rise in the Church

In 1429, Alonso accomplished one of his greatest achievements: helping to end the Western Schism. The schism had originated in 1378 after the French Pope Clement V agreed to move the papal capital from Rome, Italy, to Avignon, France. Clement did so to submit to King Philip IV of France and escape Rome’s factionalism. Philip had previously clashed with Pope Boniface VIII and welcomed Clement’s submission. Although the capital returned to Rome in January 1377, the schism continued.

Over the following decades, a split occurred within the church after rival factions elected multiple popes. By the late 1420s, the anti-pope, Clement VIII, actively opposed the Roman pope, Martin V. On July 26, Alonso succeeded in convincing Clement VIII to surrender, which left Martin V the sole pope. Also, Alonso reconciled Alfonso V with Martin V since the two men’s relationship had cooled. With both men’s backing, Alonso became the Bishop of Valencia, one of Aragon’s most prestigious positions.

Over the next fifteen years, Alonso acted as a mediator between King Alfonso and subsequent popes. The bishop achieved an incredible diplomatic victory after Alfonso took Naple’s throne. In recognition of his new title, Alfonso agreed to recognize Eugene IV as pope. The king would supply the pope with military aid, while his illegitimate son, Ferrante, would be allowed to inherit Naples. As thanks, Eugene made Alonso a cardinal on May 2, 1444.


Upon becoming a cardinal, Alonso Borgia resigned from his positions in Aragon and traveled to Italy. In 1445, he would use his position to gain favors for the Borgias. As a result, Alonso’s nephew, Rodrigo Borgia, moved up the church’s ranks quickly. By 1449, Alonso had gained Pope Nicholas V’s permission to allow Rodrigo to collect income from his many offices. This action allowed the cardinal’s nephew to become a wealthy man quickly.


On March 25, 1445, Nicholas V died in his sleep. Alonso, along with his fellow cardinals, gathered to decide who would be the next pope. By early April, the cardinals had agreed upon a compromise candidate: Alonso Borgia. Due to his advanced age, it was believed that his reign would be short. Despite this, the old cardinal had a respectable career as both a diplomat and lawyer. Upon his coronation on April 20, Alonso became known as Pope Calixtus III.

The Fall of Constantinople
The Fall of Constantinople

On May 29, 1453, the Byzantine Empire collapsed after the fall of Constantinople. The empire had served as a critical eastern barrier between Christian Europe and the Muslim Ottoman Empire. The Ottoman’s new western foothold threatened Europe’s security, and many feared an invasion. Pope Calixtus III viewed the recovery of Constantinople as essential and made it the focus of his pontificate. Upon becoming pope, he called for a crusade against the Ottomans.

Calixtus III’s call for support received a lackluster response from Europe’s rulers. The Hundred Years’ War had unofficially ended between England and France, which had exhausted both countries. Both kingdoms had involved other countries in the conflict and left Europe in a state of division. Despite the lack of support, the pope remained determined. Calixtus raised funds by selling off his predecessor’s more extravagant items, such as silver candles and gold dining ware. Through the sale of these items, the pope assembled soldiers, supplies, and ships.

The Crusade

Calixtus III’s fleet would experience limited success during the crusade. The crusaders would expel Ottoman forces from the Aegean islands and Belgrade. However, they would prove unsuccessful in removing the Ottomans from Constantinople. As the crusade went on, the pope granted his nephew, Rodrigo, a cardinals hat in September 1456. In turn, Calixtus later promoted Rodrigo as vice-chancellor of the church. Through his uncle’s efforts, the cardinal now profited from some of the church’s highest positions.

Final Years

During the last two years of his life, Calixtus III’s health began to decline. As the pope’s health failed, he turned over many day-to-day operations to Rodrigo and trusted associates. By July 1458, Calixtus started suffering from attacks of gout. In early August, his health rapidly declined, and the old pope finally died on August 6.


Calixtus III was the first member of the Borgia family to become pope. Although criticized for promoting his relatives, Calixtus created a path for other Borgias to succeed in the church. His nephew, Rodrigo, benefited the most from his uncle. Due to his early guidance, Rodrigo would become the second Borgia pope, Alexander VI, in 1492.


Hollingsworth, M. (2014). The Borgias: History’s Most Notorious Dynasty. London: Quercus Publishing Plc.

Calixtus III. (2020, December 27). Retrieved February 04, 2021, from https://www.britannica.com/biography/Calixtus-III-pope


Andy Tree

I'm a European history enthusiast who seeks to share his passion with others. I hope to inform and inspire readers with my posts!

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