Calendar Considerations
We live in a world in which most official dates are recorded on a common calendar. It wasn't always so. If your families' history is confined to Europe and America, you must be aware of the change from Julian to the Gregorian calendar. If you're working with Jewish records, be aware the some European Jewish records will use the Hebrew calendar. If your genealogical ramblings take you farther afield, you need to be cognicient that other calenders were, and still are, used in other parts of the world. Wikipedia has a list of calendars and where and when they were used. You can use the Fourmilab Calendar Converter to convert dates to and from other calendars
The Gregorian Calendar
Julius Caesar implemented the Julian calendar in 45 BC, realigning the Roman calendar with the equinoxes. His calendar assumed that a solar year was 365.25 and compensated for the annual extra quarter day by adding an extra day every fourth year. The Julian calendar also moved the start of the year from March to January.
Since the actual solar year (the time for the earth to complete one orbit of the sun) is 365.2422 days, not 365.25, that .0088 difference accumulated. After a thousand years, this impacted the relationship between the calendar and the Spring equinox, important because the date for Easter is related to that equinox.
In 1545, the Council of Trent authorised Pope Paul III to reset the calendar so the alignment of Easter and the Spring Equinox would be restored to that held at the First Council of Nicaea in 325 A.D and to reform the calendar to continue that proper alignment.
On 24 Feb 1582, six popes later, Pope Gregory XIII issued the papal bull "Inter gravissimas". The bull deleted the 10 days of accumulated error by having Thursday, 4 Oct1582 be followed by Friday, 15 Oct 1582. It also changed the leap year rule to be:
- Every year that is exactly divisible by four is a leap year,
except for years that are exactly divisible by 100. - Years that are exactly divisible by 100 are only leap years
if they are also exactly divisible by 400.
Wikipedia has more information on the Gregorian Calendar.
New Year's Day
Most early civilizations designated some time around the Spring Equinox as the start of the year. The early Roman calendar started the year on March 1st. When Julius Caesar reformed the claendar, he added 67 days to 46 B.C. by making 45 B.C. begin on January 1st. After the fall of the Roman Empire, various areas used differant dates (Christmas, March 1st, March 25th, Easter). In 567 AD, the Council of Tours abolished January 1st as the beginning of the year.
Starting in 1362, January 1st was slowly re-adopted as the first day of the year.
Genealogical Considerations
When researching your family's history, just be aware that recorded dates may be inconsistent.
The Dates May Vary
It took nearly 300 years before most of Europe adopted the Gregorian calendar, during which time the date of the same day could vary from country to country. Most Catholic countries adopted the new, Gregorian calendar very quickly. Protestant and Eastern Orthodox countries resisted what many perceived as a “Catholic Plot” for many, many years. The Eastern Orthodox Churchs still use the Julian Calendar, with the liturgical year starting on September 1st.
The Year May Vary
Complicating all this, differant countries started the year on differant days. As countries moved to January 1st, it was not uncommon in for old documents to indicate whether a date was Old Style or New Style. Sometimes, both years would be recorded.
Resistance
Even when a country changed to the new calendar, not everyone complied. Organizations, particularly Protestant churches in New England, and individuals often refused to use the new system. For example, it was not uncommon in portions of the American south for some Protestant Scots-Irish settlers to celebrate Christmas on January 6th, referred to as Old Christmas.
For more information on how this shows up in English and colonial records, visit this Connecticut State Library page.
If you want to go deeper, Mike Spathaky has an excellent article Old Style and New Style Dates and the change to the Gregorian Calendar: A summary for genealogists on this subject.
When and Where Calendars Changed
| Adopted January 1st as the Start of the Year | |
| 1362 | Lithuania |
| 1544 | Holy Roman Empire (Catholic states) |
| 1556 | Spain, Poland, Portugal |
| 1559 | Holy Roman Empire (Protestant states) |
| 1559 | Prussia & Sweden |
| 1564 | France |
| 1576 | Southern Netherlands |
| 1579 | Lorraine |
| 1583 | Dutch Republic |
| 1600 | Scotland |
| 1700 | Russia |
| 1750 | Tuscany |
| 1752 | Great Britain (& colonies) |
| 1797 | Venice |
| 1918 | Ottoman Empire |
| 1923 | Greece |
| Adopted the Gregorian Calendar | |
| 1582 | Italy, Spain, France, Portugal, Poland, Catholic Low Countries & Luxembourg (& colonies.) 4 Oct 1582 was followed by 15 Oct 1582 |
| 1583 | Austria, Catholic German states |
| 1584 | Bohemia |
| 1587 | Hungary |
| 1610 | Prussia |
| 1648 | Alsace |
| 1682 | Strasbourg |
| 1700 | Protestant German states, Swiss Cantons, Protestant Low Countries, Norway, & Denmark |
| 1752 | Great Britain (& colonies) 2 Sep 1752 was followed by 14 Sep 1752 |
| 1753 | Sweden & Finland |
| 1872 | Japan |
| 1875 | Egypt |
| 1896 | Korea |
| 1912 | China & Albania |
| 1915 | Latvia & Lithuania |
| 1916 | Bulgaria |
| 1918 | Russia & Estonia |
| 1919 | Romania & Yugoslavia |
| 1923 | Greece |
| 1926 | Turkey |
Contact: Message me via FamilySearch (Member JWGreenley) or Ancestry.com (Member JWGreenleyJr).
