How can you NOT know what year you were born?

"But at my back I always hear
Time's winged chariot hurrying near"
- To his Coy Mistress, by Andrew Marvell

I enjoy doing genealogy, especially now-a-days with so many resources available on the Internet. But one thing always amazes me: the multiplicity of dates listed for the life event of a single person. A relative might be online as born on 15/1/1753 or 1/15/1752 or 15 Jan 1752/3 or 26 Jan 1753 or 1 Feb 1753 and all could be correct to some degree. How can that be?

The answer begins with the year 1582 when the Catholic church took action regarding calendar creep. The Julian calendar used since ancient Rome had a leap year every four years which is very good but still has an error of 11 minutes per year compared to the sun. By the 1580's this had accumulated to 10 days of error. In 1582 Pope Gregory XIII decreed changes:
1. All calendars in October would be advanced by 10 days to sync with the sun
2. Leap year would be skipped in years divisible by 100 (l900 was not a leap year) unless also divisible by 400 (so 2000 is a leap year) to eliminate the small drift.

Now this occurred after the Protestant Reformation so many countries ignored the papal decree which led to more confusion as different countries had different dates. Imagine it's Oct 11 in Italy with a contract to deliver something to Germany on their Oct 2, tomorrow. Eventually all(?) countries updated their calendars to the Gregorian system. This did not occur until 1752 in England by which point they had to skip 11 days to catch up. Wednesday, 2 September 1752 was followed by Thursday, 14 September 1752.

Back to genealogy: John Smith was born Jan 15th, 1752 so this was just before the calendar change in September in England, right? Wrong. Like many murder mystery novels I've held back a vital clue. Gregory also changed the start of the year from March 25 to January 1. Under the old calendar the year went Nov 1752, Dec 1752, Jan 1752, Feb 1752, March 1752, April 1753 (new year).  Jan 15 was very late in the year 1752 under the Julian calendar but would be listed as 1753 under new system. Genealogists recommend writing this as 15 Jan 1752/3.

The change of starting month also affects Quaker dates. [I have a lot of Quakers in my family tree.] Quakers refused to use the days of the week names since this mention foreign gods: Thursday (Thor), Wednesday (Odin or Wodin), Saturday (Saturn). So they would list a birth as the 15th day of the 1st month of the year 1752. But what is the 1st month?  It was March prior to 1752 and January afterwards.

When doing genealogy dates should be written as
day(#) Month(full or 3 letter abbreviation) year(4 digits)
to avoid the confusion of the American 1/15/1752 vs the European 15/1/1752 for the same date. I saw this problem in a British relative last night - some records said  7 Oct and others 10 July - clearly someone was confused over 10/7 vs 7/10.

But the confusion does not stop there. Some people try to be helpful by "correcting" dates from the Julian to Gregorian (especially if the person was born under one calendar and died under the other). They add 11 days to the birthday so John Smith gets a birth date of 26 Jan 1753. The trouble is how do I know if the date was adjusted or not? I don't. Hence the formula  15 Jan 1752/3 to indicate a Julian date between Jan 1 to March 24 without "correction".

Bottom Line

If you follow the rules above will you have the correct date? Maybe not. There's one more common point of confusion. Many dates are taken from old church records which typically record the Christening date (baptism) and the burial date instead of the birth date and date of death. In my example at top, 1 Feb 1753, might be the baptismal date and entered mistakenly as the birth date for John Smith. It's important to know what event the date represents.