Pope Gregory XIII
Pope Gregory XIII reformed the calendar the world still uses, and celebrated a massacre. Born Ugo Boncompagni in Bologna in 1502, he taught law at its university for years — his students included Charles Borromeo and future cardinals — and fathered a son before taking orders. He served at the Council of Trent, was sent as legate to Spain, and was elected pope in 1572. He was an energetic administrator of the Counter-Reformation. He founded or endowed a large number of seminaries and colleges across Europe, including the Roman College, refounded as the Gregorian University, and national colleges for English, German and Hungarian students intended to train missionary priests for territories lost to Protestantism. He regularised the system of permanent nunciatures, which is the origin of modern Vatican diplomacy. His reputation is permanently marked by his response to the St Bartholomew's Day massacre of French Protestants in August 1572, in which thousands were killed. Told that a Huguenot conspiracy had been foiled, he ordered a Te Deum sung, struck a commemorative medal and commissioned frescoes of the killings in the Vatican. The calendar reform is the lasting achievement. The Julian calendar assumed a year of 365.25 days, about eleven minutes too long, and by the sixteenth century the accumulated error had shifted the equinox ten days from where the Church had fixed it for calculating Easter. Working from a scheme by the physician Aloysius Lilius and refined by the Jesuit mathematician Christopher Clavius, the bull Inter gravissimas of February 1582 dropped ten days — 4 October was followed by 15 October — and dropped three leap days every four centuries. Catholic states adopted it at once; Britain waited until 1752, Russia until 1918. He died in 1585.
- Lived: 1502 CE – 1585 CE
- Nationality: Italian
- Roles: pope, reformer
