It’s a date!

Studying the ’45 Uprising we have the joy of being caught in a time before the introduction of the Gregorian calendar. As such, dates can be something of a little nightmare for those who are unaware of how they came about, and the added mystery of two dates on the same document can be confusing.

So, to solve this problem we’ve tried to explain dates in the simplest way we can considering they try to confuse you at every turn.


First things first there are two calendar systems, the Julian Old Style calendar and the Gregorian New Style calendar. Most European countries changed over to the new (Gregorian) style by the time of the ’45 but the protestant countries were reluctant as the new calendar had been initiated by the Vatican which is why we have the confusion of different dates.

The main reason for the change in calendars was a discrepancy between the calendar year and the solar year. (Yes, there is more than one year.)

The calendar Julian year was given as 365.25 days, so every year had 365 days and every fourth year an extra one making it a leap year. But. 365.25 is in fact a slight over estimate of the solar year, or the time taken for the Earth to make one complete revolution around the sun. This slight discrepancy meant that by the sixteenth century a difference of about ten days had accumulated between the calendar year and the solar year. May not seem like a big deal but to keep in line with the seasons it’s best to try and stick with the solar year.


The Gregorian calendar was first introduced in 1582 by Pope Gregory XIII to solve this problem. He corrected the error already accumulated by adding ten days to the year 1582 and changed the calendar to make the last year of every fourth century an additional leap year. This meant that the Gregorian calendar year differs from the solar year by only 26 seconds—accurate enough for most mortals, since this only adds up to one day’s difference every 3,323 years.

In addition to this, just to make things even more exciting, he also decreed that the year start on the 1st January and not the 25th March as it had previously.Before the Gregorian calendar the start of the year was often a day of religious significance and until the introduction of the Gregorian style 25th March was the start of the new year in Britain 25th March was used as this was the Feast of Annunciation or Lady Day, the day that celebrated the Virgin Mary.  Hence, dates would be for example, 24th Mar 1714 followed by 25th Mar 1715.


Many places including Spain, Portugal and Italy adopted the Gregorian calendar very swiftly but others were slow to take up the new system. As a result two calendars were being used across Europe and many historical documents displayed two dates on them to reflect this e.g. 11/21 March 1651 to reflect the Julian and Gregorian styles.

In 1600 Scotland began to change when it made 1st January, New Years Day which resulted in 1599 having only nine months but it did not entirely convert to the Gregorian style which cut ten days out of the year to align with the solar year.

England meanwhile began the change in 1752 by making 1st January, New Years Day and then switched fully to the Gregorian calendar in September 1752 bringing dates forward 11 days which brought it into line with the rest of Europe. Scotland also removed the 11 days at this time bringing it into the Gregorian style. Finally, both England and Scotland were on the Gregorian calendar as we know it today and everyone’s dates were the same!


Hopefully that makes some sense! As always if you’re not too brain tired please share, follow, like, tweet and deliberate over exactly which day it is. All the best.

K & D