What happened in France between 9 and 20 December 1852? Literally nothing. Those days were cancelled and people went straight from Sunday 9 December to Monday 20 December. It was all part of King Henry III’s decision to transition from the Julian calendar (established by Julius Caesar himself) to the Gregorian calendar, as set out by Pope Gregory XIII, to iron out a few miscalculations here and there. The change took place on different dates all over the world, which doesn’t sound chaotic at all! Needless to say, those who celebrated their birthdays between 10 and 19 December got a rough deal that year!