Six and a half million Britons went to bed on September 2, 1752, and woke up on September 14. The reason? The Calendar (New Style) Act of 1750, of course.

Six and a half million Britons went to bed on September 2, 1752, and woke up on September 14. The reason? The Calendar (New Style) Act of 1750, of course.

Now, your average Brit had as much knowledge of Parliament then as we do of day-to-day life in the 1750s, so this might need a little unpacking. You see, it’s all to do with calendars—the way we tabulate time—and how Britain fell out of sync with the world, and felt the need to catch back up. And what’s more, it goes back 170 years prior to 1752.

In 1582, Pope Gregory XIII was 10 years into his reign as leader of the Catholic church. He had a problem with Easter. The Julian calendar that the church (and large swaths of the world) used at the time measured a year as 365 days and 6 hours long.

That’s close, but not quite right. The average length of a year is 365 days, 5 hours and 49 minutes. The 11 minutes difference might not seem like all that much, but compounded over 1300 years, it begins to add up. So on February 24, 1582, Pope Gregory XIII released a papal bull—a declaration from the leader of the Catholic church—decreeing that those under the dominionship of his church would have to skip some days. Spain, large parts of Italy (which was not yet unified), the Netherlands, France, Portugal, Luxembourg, and Poland and Lithuania (who were at the time tied under a commonwealth) all adopted Gregory’s bull that year.

Austria, Switzerland, Germany, Hungary, and Prussia all followed in the next 50 years, so that large parts of Europe were now ticking off days on their shiny new Gregorian calendars.