Pope Gregory XIII Deleted Ten Days in 1582
In October 1582, the day after Thursday the 4th was Friday the 15th. The calendar had drifted and the Vatican snipped out the difference.
On Thursday, October 4, 1582, people in Spain, Portugal, Poland, and the Italian states went to bed. They woke up on Friday, October 15. Ten days had vanished by papal decree.
The Julian calendar, built under Caesar in 46 BC, assumed the solar year was exactly 365.25 days. It isn't. It's about 11 minutes shorter. Over sixteen centuries, those minutes had compounded into a ten-day drift between the calendar and the seasons. The spring equinox, set by the Council of Nicaea at March 21 for the purpose of dating Easter, was falling on March 11.
Pope Gregory XIII issued the bull Inter gravissimas in February 1582. It did two things: it dropped ten days to realign the equinox, and it tightened the leap-year rule. Years divisible by 100 would no longer be leap years — unless they were also divisible by 400. That's why 2000 was a leap year and 1900 wasn't.
Protestant states refused to take orders from Rome and kept the old system for decades. Britain and its American colonies switched in 1752, by which time the drift had grown to eleven days. Diarist Samuel Pepys's successor generation saw newspaper headlines about mobs shouting 'Give us our eleven days.' The shout was probably apocryphal, but the anxiety was not: taxes, rents, and saints' days all snapped.
Russia held out until 1918. Greece was the last Orthodox country in Europe to civil-switch, in 1923.
Make Recess yours.
Sign in to save the ones you loved, never see the same thing twice, and tell us what you want more of.