Long before St. Patrick’s Day became synonymous with the color green, its namesake saint — and even Ireland as a whole — was more closely associated with various shades of blue. St. Patrick is often credited with spreading Christianity throughout Ireland, and he became known as the patron saint of the country. The earliest known depiction of the saint — found in a 13th-century French manuscript — shows him clad in a blue robe, and he was often associated with the cool hue. 

The color blue was also used to represent Ireland itself, starting with the actions of King Henry VIII in 1541. The English monarch declared himself king of Ireland and presented the Irish kingdom with a new coat of arms featuring a golden harp on a dark blue background — the first link between Ireland and the color blue. Two centuries later, in 1783, England’s King George III established the Order of St. Patrick in Ireland, whose members wore outfits in a shade known as “St. Patrick’s blue.” However, these symbols were imposed upon the Irish people by their English oppressors, and the color blue never reflected the true Irish identity. It wasn’t until the Irish Rebellion of 1798 that the Irish adopted the color green — a shade also embraced by nationalists during an earlier 1642 rebellion — as a symbol of national pride, replacing the old blue colors found in many Irish flags and emblems. Around this time, green was also introduced to St. Patrick’s Day festivities, and it became the standard hue of the holiday shortly after.

February is normally the shortest month of the year, but in 1712, Sweden extended the month all the way to February 30. This calendrical anomaly occurred as the country awkwardly shifted between the Julian and Gregorian calendars, which had about a 10-day gap between them. Pope Gregory XIII had introduced the latter calendar in 1582 to fix large discrepancies between the solar year and calendar date that the Julian calendar had incurred. Nations around the world slowly adopted the new calendar, and Sweden finally opted to do so in 1700.

The year 1700 happened to be a leap year in the Julian calendar, but not in the Gregorian version, widening the gap even further; March 1 in the Julian calendar corresponded to the Gregorian March 12. Sweden planned to gradually switch to the Gregorian calendar by omitting 11 leap days over the course of 40 years, but that plan was derailed when leap years were still mistakenly observed in 1704 and 1708. By 1712, Sweden’s timekeeping was such a mess, the country planned to shift back to the Julian calendar starting on March 1. (It also wanted to ensure that Easter would be celebrated on a Sunday.) To accomplish this, Sweden added February 29 — as 1712 was already a leap year to begin with — plus an extra day, February 30, to make up for the leap day it had omitted back in 1700. The country finally made the permanent shift to the Gregorian calendar in 1753, bridging the 11-day difference by jumping from February 17 to March 1.