Pope Gregory XIII

On this day in history: Pope Gregory XIII born

History of Italy News

On 7th January 1502, one of the most influential figures in the history of timekeeping was born – Pope Gregory XIII. His contributions to the world extend beyond the confines of religious leadership, as he played a pivotal role in reforming the calendar system.

Born as Ugo Boncompagni in Bologna, Italy, on 7th January 1502, Gregory XIII belonged to a noble family. His journey towards the papacy was marked by a remarkable academic career, excelling in law and theology.

Before he took holy orders, Ugo had an affair with Maddalena Fulchini, who gave birth to his illegitimate son, Giacomo Boncompagni.

Pope Paul III summoned Ugo to Rome in 1538 to work for him in a judicial capacity. He went on to work for Pope Paul IV and Pope Pius IV. Ugo was made Cardinal Priest of San Sisto Vecchio and sent to the Council of Trent by Pius IV.

He was also sent to be legate to Phillip II of Spain and formed a close relationship with the Spanish King.

Ugo Boncompagni became Pope Gregory XIII in 1572, aged 70, following the death of Pope Pius V.

Pope Gregory is best known for his introduction of the Gregorian calendar, but there was much more to his tenure as pope than the calendar.

Ecclesiastical Reforms

Pope Gregory XIII focused on strengthening the Catholic Church through various ecclesiastical reforms. He worked to enhance the discipline of the clergy and improve the administration of the Church.

His efforts aimed at maintaining the spiritual authority and moral influence of the Catholic Church during a period marked by religious and political challenges.

Missionary Work

Gregory XIII was a strong supporter of missionary activities. He encouraged and sponsored missions to various parts of the world, particularly in newly discovered territories.

The expansion of Catholicism into different regions was a priority for the pope, and he sought to spread the influence of the Church globally.

Support for Education

Understanding the importance of education, Pope Gregory XIII was a patron of learning and sought to promote intellectual pursuits. He supported the establishment of schools and educational institutions, emphasising the need for a well-educated clergy.

One of his notable contributions was the founding of the Roman College (now the Gregorian University) in 1551, which became a significant centre for Jesuit education.

Diplomacy and International Relations

Pope Gregory XIII navigated the complex landscape of European politics during a period marked by religious conflicts. He engaged in diplomatic efforts to maintain the stability and influence of the Papal States. The pope played a role in mediating disputes between Catholic nations and addressing issues related to the Counter-Reformation.

Art and Culture

The patronage of the arts flourished during Gregory XIII’s papacy. He continued the grand architectural projects initiated by his predecessors, contributing to the embellishment of Rome. Gregory XIII supported artists and architects, leaving a lasting impact on the cultural landscape of the Vatican City.

The Inquisition

Pope Gregory XIII, like many popes of his time, was involved in the activities of the Roman Inquisition. The Inquisition aimed to combat heresy and ensure doctrinal orthodoxy within the Catholic Church. While the Inquisition was a controversial institution, Gregory XIII believed it was necessary for maintaining religious purity and unity.

Gregorian Calendar: A Timeless Legacy

One of the first challenges Pope Gregory XIII faced upon assuming the papal throne was the discrepancy in the Julian calendar, which had been in use since 45 BCE. The Julian calendar, established by Julius Caesar, had a minor error in its calculation of the length of the solar year. This miscalculation led to a gradual misalignment between the calendar and the astronomical seasons.

To address this issue, Pope Gregory XIII convened a commission of experts, including astronomers and mathematicians, to propose a solution. The outcome of their work was the Gregorian calendar, introduced in October 1582. The key adjustment was the omission of ten days from the calendar to realign it with the solar year.

The Gregorian calendar also incorporated a leap year rule, which stipulated that a year divisible by 4 is a leap year unless it is divisible by 100 but not by 400. This fine-tuning helped to bring the calendar year more in line with the Earth’s orbit around the sun.

Adoption of the Gregorian Calendar

The Gregorian calendar was introduced on 4th October 1582, with the following day being Friday 15th October.

Initially met with scepticism, the Gregorian calendar faced resistance from some quarters. However, its accuracy and practicality gradually won over most of the Christian world. Catholic countries in Europe, including Italy, Spain, and Portugal, adopted the Gregorian calendar almost immediately. Other countries, such as France and the Catholic parts of the Holy Roman Empire, followed suit in subsequent years.

However, the Protestant regions of Europe were more resistant to the change, viewing it as a Catholic innovation. It took several decades and, in some cases, even centuries for Protestant countries to adopt the Gregorian calendar.

Impact on Society

The Gregorian calendar significantly improved the accuracy of timekeeping and brought about a standardised method for recording dates. Its adoption had far-reaching consequences for various aspects of society, including commerce, agriculture, and cultural events.

The synchronicity provided by the Gregorian calendar facilitated better coordination and communication between nations, fostering a more interconnected global community.

Religious Significance

Pope Gregory XIII’s calendar reform was not solely a secular endeavour. It also had profound implications for the calculation of religious observances, particularly Easter. The timing of Easter had long been a contentious issue, with different Christian communities using different methods to determine the date.

The Gregorian calendar aimed to establish a consistent formula for calculating the date of Easter, bringing greater unity to Christian celebrations.


Pope Gregory XIII’s legacy is enduring, marked by the widespread adoption and continued use of the Gregorian calendar. His contribution to the field of timekeeping has transcended religious boundaries, becoming a fundamental aspect of our daily lives.

However, his papacy was also multifaceted, encompassing not only the reform of the calendar but also a broad range of activities aimed at strengthening the Catholic Church, promoting education, fostering cultural development, and navigating the intricate political landscape of his time.

His legacy endures as a pope who left a lasting impact on both the religious and cultural aspects of the Catholic Church and the Papal States.

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