On this day October 15, 1582
Pope Gregory XIII implements the Gregorian calendar. In Italy, Poland, Portugal, and Spain, October 4 of this year is followed directly by October 15.
The Gregorian calendar is the internationally accepted civil calendar. It was first proposed by the Calabrian doctor Aloysius Lilius, and decreed by Pope Gregory XIII, after whom the calendar was named, on 24 February 1582 by the papal bull Inter gravissimas.
It was adopted later that year by a handful of countries, with other countries adopting it over the following centuries.
Britain and the British Empire (including the eastern part of what is now the United States) adopted the Gregorian calendar in 1752 by which time it was necessary to correct by 11 days. Wednesday, 2 September 1752 was followed by Thursday, 14 September 1752 to account for 29 February 1700 (Julian).
It is a reform of the Julian calendar. Gregory’s bull does not ordain any particular year-numbering system, but uses the Anno Domini system which counts years from the traditional Incarnation of Jesus, and which had spread throughout Europe during the Middle Ages. That is the same year-numbering system that is the de facto international standard today.
Pope Gregory XIII born in the city of Bologna, Italy where he studied law and graduated in 1530. Afterwards, he taught jurisprudence for some years; his students included notable figures such as Alexander Farnese, Reginald Pole and Charles Borromeo.
Unlike some of his predecessors, Gregory XIII was to lead a faultless personal life, becoming a model for his simplicity of life. Additionally, his legal brilliance and management abilities meant that he was able to respond and deal with the major problems quickly and decisively, although not always successfully.