The Gregorian calendar was introduced.

Pope Gregory XIII issued the papal bull Inter gravissimas to establish the new calendar in Rome, Papal States (modern-day Italy).

It replaced the Julian calendar to correct inaccuracies in calculating the solar year.

To align the calendar, 10 days were skipped, October 4, 1582, was immediately followed by October 15, 1582.

Catholic countries, including Spain, Portugal, and Italy, adopted the calendar immediately in 1582.

Other countries, such as England, did not adopt the Gregorian calendar until 1752.
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