Sweden Once Had a February 30 in 1712
You've probably never questioned why February ends on the 28th or 29th, but in 1712, Sweden broke this universal rule by adding a February 30th to their calendar. This peculiar date wasn't a mistake or a typo – it was a deliberate decision by King Charles XII to fix Sweden's messy shift between calendar systems. While the rest of Europe had already sorted out their dates, Sweden's unique solution to their calendar crisis would lead to even more fascinating complications.
The Unusual Tale of Sweden's Calendar Switch
While most calendar changes throughout history have been straightforward switches, Sweden's attempt to shift from the Julian to Gregorian calendar stands out as a uniquely complex saga.
You might be surprised to learn that in 1699, Sweden planned a gradual 40-year alteration, intending to skip one leap year every four years. This unusual approach quickly led to calendar confusion when the Great Northern War disrupted their careful plans.
After successfully omitting the leap year in 1700, Sweden accidentally observed leap years in 1704 and 1708, creating a peculiar situation where they were neither aligned with the Julian nor the Gregorian calendar. To resolve this predicament, they created February 30 in 1712.
The country finally made a definitive switch when they jumped from February 18, 1753 to March 1, 1753.
Their unique "Old Style + 1 day" system caused such chaos in international communications that officials had to devise a bold solution.
How a Failed Transition Created an Extra Day
After Sweden's botched attempt at a gradual calendar shift, officials faced an unprecedented dilemma that led to one of history's most peculiar dates. The plan to skip leap days between 1700 and 1740 fell apart when the Great Northern War disrupted the change.
The new calendar created conflict as Protestant nations resisted accepting changes from Rome. You'd be surprised to learn that Sweden accidentally kept two leap days they should've omitted in 1704 and 1708, creating one of history's strangest calendar anomalies.
To fix this mess, Swedish officials made a remarkable decision: they'd add February 30 to the 1712 calendar. This unusual historical adjustment created the only known instance of a 30-day February, making 1712 a 367-day year.
King Charles XII officially declared this correction, known as "tillökningsdagen," to help Sweden return to the Julian calendar. The country would continue using the Julian calendar until finally adopting the Gregorian system in 1753.
The Great Northern War's Impact on Swedish Timekeeping
The Great Northern War dramatically shaped Sweden's calendar confusion during the early 18th century. As Sweden fought against Russia and its allies, military logistics became increasingly complex due to calendar discrepancies between Swedish forces and their European counterparts. The Julian calendar error accumulated over time, making date coordination even more difficult.
The war's strain on resources and manpower forced Sweden to abandon its planned shift to the Gregorian calendar, leading to several complications:
- Military coordination with allies became more challenging due to different date systems
- Supply chains were disrupted by misaligned scheduling
- Battle planning suffered from timing inconsistencies
- Record-keeping became problematic across territories
You can trace the impact of these calendar issues throughout the war, as King Charles XII struggled to maintain Sweden's position in the Baltic. The decisive Battle of Poltava in 1709 marked a turning point that further strained Sweden's ability to manage its military operations effectively.
The conflict not only drained Sweden's resources but also highlighted the urgent need for a standardized timekeeping system, eventually leading to the adoption of the Gregorian calendar in 1753.
Sweden's Final Path to the Gregorian Calendar
Since Sweden's initial attempt to adopt the Gregorian calendar had failed miserably, officials needed a fresh approach to resolve their timekeeping crisis.
The original plan to transition over 40 years failed due to poor administration and inconsistent application of calendar changes.
This unusual situation even created a February 30 date in 1712 during the transition period.
After years of calendar confusion, you'd find Sweden finally making a decisive move in 1753. The change occurred when Wednesday, February 17, suddenly jumped to Thursday, March 1 – effectively skipping 11 days to align with the Gregorian system.
This shift impacted not just Sweden's historical timeline but also Finland's, which was under Swedish rule at the time.
When Russia later conquered Finland in 1809, the change remained intact, though Finnish officials had to date documents in both Julian and Gregorian styles until 1917.
The alteration finally brought both nations in line with Western Europe, ending decades of complicated date-keeping.
