On a snowy day at the end of February 1712, a young couple named Svven and Elena Hall got married in the Swedish town of Ystad. The wedding, though completely unremarkable in all other aspects, was unusual in that it took place on a date that has never existed in any other country at any time before or since—the 30th of February.
This extension of February by an extra day was just one of the unusual consequences of Europe’s adoption of the Gregorian calendar, the familiar system of twelve months still in use today. It was introduced by Pope Gregory XIII in 1582 as a correction to the Julian calendar, set out by Julius Caesar in 45 BC, which after sixteen centuries years of use had fallen eleven days behind the solar cycle.
While simply eliminating those extra days would provide a temporary fix, Gregory also wanted to make sure that his new calendar would be self-correcting in the long term. Thanks to the work of the Italian astronomer Aloysius Lilius, this was done by treating every fourth year as a leap year with the exception of those century years such as 1700 or 1800 that did not divide by 400. Those that did – such as 1600 and 2000 – would remain leap years and continue to have 29-day-long Februaries. With these modifications, the new calendar year would divert from the solar year by a mere 26 seconds – an improvement in accuracy of nearly 11 minutes.
Before the new calendar could take off, each country needed to be persuaded to wipe out eleven days from its history. Catholic countries such as France, Spain, Portugal, Italy and the Netherlands were easy enough to convince, but Protestant countries such as England and Germany strongly resisted this command from the Vatican. While half the world had leapt ten days into the future, the other half was both figuratively and literally stuck in the past.
Britain and its Empire eventually caught up in 1752, when the days between September 2nd and 14th were famously stricken from the calendars. The only major power to successfully resist the change beyond the 18th Century was the Russian Empire, which retained the old style dating convention until the Communist Revolutions of 1917. This means that the famous October Revolution outside the Winter Palace actually took place in November, and the February Revolution was really held in March.
As confusing as these changes may initially have been, most people got used to the new calendar soon enough. The one country that really made things difficult for itself, however, was Sweden—which by 1700 also contained much of modern-day Finland. Instead of skipping eleven days all in one go the 18-year-old King Charles XII decided to phase the change in slowly, by canceling the leap days scheduled over the coming forty years.
The plan worked well enough in the first year, 1700, but the outbreak of war soon pushed calendrical reform to the bottom of Charles’ agenda. In the fog of conflict, nobody bothered to cancel the next two leap days—which meant that by March 1708 the country was on its own unique time zone.
Rather than make the sweeping reform he’d refused to consider twelve years earlier and eliminate ten days with the stroke of a pen, Charles thought it easier to bring his country back in line with the Julian calendar by compensating for the one day they had skipped over. The year 1712 therefore had two leap days, February 29th and February 30th, which kept the country in line with the Julian calendar until it eventually reformed in 1753.
If the creation of February 30th strikes us as pointless now, we can at least reflect it must have been a happy day for Svven and Elena Hall. Of all the blessings heaped on the newlyweds that morning, the most treasured must have been the knowledge there would be no wedding anniversaries for either one of them to forget.
Image of King Charles XII of Sweden: Public Domain via Wikimedia Commons
