The Catholic countries of Italy, Spain, Portugal and Poland immediately adopted Pope Gregory XIII’s decree, with France and Luxembourg soon following. However, by the 1500’s the Roman Catholic Church’s influence on Europe had waned and some countries were either slow to adopt (such as Hungry in 1587), or were distrustful of the Roman Catholic Church and resisted adopting the new and improved calendar.
The notable standout was England and the English colonies (including America), which continued to use the Julian calendar long after most of Europe had switched to the Gregorian calendar. In fact, England and the colonies did not adopt the Gregorian calendar until 1752, almost 170 years after Pope Gregory XIII’s decree. However, by that time the Julian calendar had slipped 11 days relative to the Gregorian calendar.
When England and the colonies finally adopted the Gregorian calendar, it was necessary for them to omit 11 days to ‘catch up’. As a result, for England and the colonies, Wednesday, 2 September 1752 in the old Julian calendar was immediately followed by Thursday, 14 September 1752 in the newly adopted Gregorian calendar. The days in between these two dates officially do not exist.
What this Means for Genealogy
Using England and the colonies as an example, genealogists need to be aware of two things when interpreting old records after 1752. First, in many countries (including England) the general population continued to use the old Julian calendar long after the country officially adopted the new Gregorian calendar. This is particularly true of dates recorded in personal family records and documents, as opposed to official records, which usually used the Gregorian calendar.
Sometimes it is evident which calendar was used by how the date was written down in an old record. For example, dates recorded by the Julian calendar sometimes had a notation “O.S.” for Old Style, while dates recorded by the Gregorian calendar were marked as “N.S.” for New Style (see A Date Guide to English Genealogy for more information).
Secondly, different countries used different days to mark the beginning of the New Year. Depending on the country (and the region within some countries!), the first day of the New Year could be 25 December (essentially the winter solstice), 1 January, 1 March, 24 or 25 March (essentially the spring equinox). Britain and the colonies prior to 1753 typically used either March 24th or March 25th as the beginning of the New Year. This roughly corresponded to the spring equinox.