Pope Gregory XIII: Accomplishments & Legacy

Instructor: Jason Waguespack

Jason has taught Political Science courses for college. He has a doctorate in Political Science.

This lesson takes you through the accomplishments of Pope Gregory XIII. You'll learn about his service to the Catholic Church, ascension to the papacy, and his creation of the Gregorian calendar, which is still in use to this day.

Pushing the Clock Forward

In September of 1752, Benjamin Franklin wrote, 'It is pleasant for an old man to be able to go to bed on September 2, and not have to get up until September 14.' Did Franklin mean he slept for twelve days? Or did he travel ahead to the future? As inventive as Franklin was, he didn't create time travel. Actually, England and her colonies were adopting the Gregorian calendar, which had to jump 11 days ahead to correct for problems in the old calendar. Franklin and the British had one man to thank for the new calendar, Pope Gregory XIII.

Early Life

Painting of the Council of Trent
Council of Trent

Gregory XIII was born Ugo Boncompagni in Bologna, Italy, on January 1, 1502. He received his education in canon and civil law at the University of Bologna, then taught jurisprudence at the same university from 1531 up to 1539, when he departed for Rome. At the age of forty, Boncompagni was ordained a priest. Boncompagni's knowledge and expertise of canon law drew the attention of the current Pope, Pius IV, who sent him on various diplomatic missions. Boncompagni continued to move up in the ranks of the church, becoming Bishop of Viesti in 1558, and by 1565, he was a cardinal. Boncompagni also attended the final and most troubled meeting of the Council of Trent in Italy, lasting from 1562 to 1563. The Council of Trent worked to deal with the Protestant Reformation and clarify Catholic doctrine.

Becoming Pope

Pope Gregory XIII
Gregory XIII

Upon the death of Pope Pius V, the cardinals met, and on May 14, 1572, elected Boncompagni as Pope. Boncompagni decided to take the name Gregory XIII. The new pope pledged to carry out the reforming decrees made by the Council of Trent. He told bishops to make their residence in their sees and to meet the obligations of their office. A strong believer in education, Gregory XIII established a number of seminaries and colleges, including the Gregorian University, to train missionaries and priests.

Gregorian Calendar

Engraving of Gregory XIII
Gregory XIII

At the time of Gregory XIII's papacy, the main calendar of the European world was the Julian calendar. However, the Julian calendar miscalculated the measurement of the solar year, which was actually longer than the Julian calendar, meaning the Julian calendar was losing a day per century. By Gregory XIII's time, the calendar was ten days behind the actual solar year.

The Pope enlisted the aid of Luigi Lilio Ghiraldi, a Neapolitan astronomer and Christopher Clavius, a German Jesuit, to correct the calendar. On February 24, 1582, Gregory XIII issued a bull, or a papal decree, that announced the new Gregorian calendar. This new calendar would push the date up ten days, so October 4th of 1582 would be immediately followed by the 15th. The method of calculating leap years was also revised. The calendar was initially binding on the papal states but quickly became adopted by countries under Catholic rule, and was welcomed by the astronomers Johannes Kepler and Tycho Brahe.

Further Actions as Pope

Gregory XIII was active in foreign affairs, backing the League in France and Mary Stuart in England, as well as recognizing Stephen Báthory as Poland's rightful king. However, the pope's reaction to the slaughter of Huguenots, or French Protestants, in France in August of 1572 would prove very controversial. Gregory had held a Te Deum, or a hymn of praise to God, in Rome in celebration of the massacre. While historians condemn Gregory for the Te Deum, others claim he believed the Huguenots were attempting to overthrow the French royal family and was not actually celebrating the bloodshed but the act of putting down a political and religious rebellion. Gregory's Te Deum remains controversial to this day.

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