In 1752, 11 Calendar Days Were Lost Forever: Here’s What Happened

Last Updated September 3, 2018

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If you’ve been studying your family’s history for a while, you’ve probably encountered some dates that have caused a little head scratching. It’s not uncommon at all to come across a date on a record that conflicts with our current research, for instance, or one that’s unreadable, incomplete or confusing.

The further we travel back in time, however, the more and more clear it becomes that dates are not to be taken for granted. Lunar vs solar calendars, shifting new years, double dating (it’s not what you think), missing days…it’s a lot to take in.

One of the most confounding date-related events ever in history, and one that regularly impacts genealogical researchers, is the calendar change of 1752. While we can all be incredibly glad that our ancestors had the foresight to correct calculation errors that would allow for more accurate calendars for generations to come – the change can certainly cause some confusion.

In September 1752, eleven whole days were cut from the calendar, eradicating them forever. For all intents and purposes these days simply never existed – no births, no marriages, no deaths.

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At this same time, the New Year was moved from March 25 to Jan 1st. This alone can be incredibly confusing to those of us used to thinking about a year running from Jan 1st to Dec 31st, rather than March 25th to March 24th. Imagine – a person could have been married on April 26th, 1710 and died on Feb 2nd 1710.

But what caused this change?

To understand how something like this could have happened we have to look all the way back to Julius Caesar who, in 46 BCE, proposed a reformation of the Roman calendar system that was to become known as the Julian calendar.

This refined system created a 365 day calendar year, based on the movement of the earth around the sun, with a leap year every 4 years (an extra day) and a New Year’s date of Jan 1st. The system was widely adopted, but over time the New Year slipped to March 25th to correlate with the Christian holiday, Annunciation Day (March 25th is 9 months prior to Christmas).

Regardless of this change, the Julian system become the primary calendar throughout the Roman Empire (until its fall), as well as in Europe and in European settlements around the world.

Travel quite a number of centuries into the future and Europe begins to wrestle with the fact that the Julian calendar system had not perfectly calculated leap years and has caused the calendar dates to become out of sync with celestial and religious events.

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So, in 1582 Pope Gregory XIII refined the Julian calendar mathematically to fix this mistake and created a new system which we now know as the Gregorian calendar.

Between this time and 1752 BOTH calendars, old and new style, were used in Europe in different locations – causing some rather perplexing dates for future researchers.

For instance, because the old style Julian calendar had a New Year of March 25th and the Gregorian calendar had a New Year of Jan 1st, a date existing between those times would often be written with both years.

Someone born on Jan 26th, 1696, as an example, might have their birth date recorded as Jan 26, 1696/97 or 96-97 to show that, according to the old system, that person was born in 1696 (since the new year had not yet started) but, according to the new style, they were born in 1697 (since the new year started on Jan 1st). This practice is known as double dating. 

So, what about those lost days?

In 1751, following the cue of most other European countries, Britain decided to fully adopt the Gregorian calendar and proposed and passed the Calendar Act. The act took effect in 1751 (Julian) and 1752 (Gregorian) in Great Britain and its colonies, including Colonial America.

But changing calendars left everyone with a problem. Since the Gregorian calendar accounted more accurately for leap years, it was 11 days ahead of the Julian calendar by 1752 (10 days between 1500 and 1700). To correct this discrepancy and align all dates, 11 days had to be dropped when the switch was made.

The Connecticut State Library outlines the steps taken to complete this complex calendar change.

December 31, 1750 was followed by January 1, 1750 (under the “Old Style” calendar, December was the 10th month and January the 11th)March 24, 1750 was followed by March 25, 1751 (March 25 was the first day of the “Old Style” year)December 31, 1751 was followed by January 1, 1752 (the switch from March 25 to January 1 as the first day of the year)September 2, 1752 was followed by September 14, 1752 (drop of 11 days to conform to the Gregorian calendar)

Read more here

This means that Sept 3rd-13th simply never existed for those in the Julian calendar world – including those in Great Britain and Colonial America.

To make it even more confusing, birth dates for notable individuals – like George Washington – are now often presented according to the New Style – even when the Old Style was still in use at the time. Wikipedia lists President Washington’s birth as being on Feb 22, 1732 – although, according to the calendar of the time, he was born on Feb 11, 1731 (which is what he would have likely told you his birth date was).

It is also important to note that some Julian areas in Colonial America starting implementing the Gregorian calendar earlier than the official change, so be aware of this when viewing dates on the edge.

How can you know if a date is in the old or new style when double dating was not used?

You’ll need to educate yourself. Take the time to know what the standard was in the area you are researching and look through a variety of records to orient yourself.

Many European countries adopted the Gregorian calendar much earlier than did Britain and Colonial America so doing some research on your location will help you know what to expect. You can find a table of dates when the Gregorian calendar was adopted in various countries and regions here. Knowing this information is key to knowing what format a date is in.

In some records you may also see abbreviations OS or O.S. to designate that a date was in the Old Style (Julian) or NS or N.S. for New Style (Gregorian).

How does this influence my record keeping and family tree?

Does that mean that you need to go around adjusting all of your pre-1752 ancestors’ dates to account for this calendar change? No. As genealogists we are generally less concerned with exactly how many days a person was alive and are more concerned with recording things as they appeared historically.

For this reason it is correct to record the date exactly as you find it on a record (ie in the Old or New Style) and to make a notation of O.S. or N.S. to clear up any confusion.

If you are curious about what a Julian date translates to in Gregorian, or you need to know for your research, you can use this calculator recommended by Family Tree Magazine.

There you have it – the lost 11 days! To better understand this topic and how it may impact your research you will want to do some additional reading. There are quite a few good articles and guides online that can help – such as this one from FamilySearch or the Wikipedia entry on New and Old Style dates.

By Melanie Mayo, Family History Daily Editor

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