Pope Gregory XIII (1502-1585) Namesake of the Gregorian Calendar

Over two thousand years ago, under the reign of Julius Caesar of Rome, a calendar system called the Julian calendar was adopted to better synchronize the year with the sun. The system they adopted around 45 BC replaced the Early Roman calendar, which was a ten-month calendar from about 700 years earlier. The old system began with Martius (March) and continued through Aprilis, Mauis, Junius, Quintilis, Sextilis, September, October, November, and December for a total of 304 days. Soon afterward, two more months called January and February were introduced under the second Roman ruler Numa Pompilius to create a total of 355 days in the year. Furthermore, like the concept of leap year, an additional month was observed after February every other year that was called Mercedonius. It was named in reference to the time of year when Roman workers were paid their “merces,” a Latin word for wages. The month was abolished under Julius Caesar, but if use had continued into the modern day, the name may have evolved linguistically into something like “Merse.” The newer Julian system contained the same month names and number of days as the modern calendar (and Quintilis was renamed “July” to honor the birth month of Julius) but the year’s duration was slightly miscalculated. In practice, there were 325.25 days per year, but the true solar year has 325.2422 days. Over a period of many centuries, the small discrepancy became evident when seasonal events like the solstices and equinoxes had drifted more than a week from their traditional dates. 

By the second half of the 1500s, calendar events were off by about eleven days. Under the jurisdiction of Pope Gregory XIII, he appointed a physician and an astronomer to fix this problem. After several years, in 1582, a new “Gregorian” calendar system was introduced to account for the inaccuracies that had accumulated. However, other countries did not agree with the motive to alter the calendar and the Julian calendar remained in place for those locations. The colonization of North America took place before the modern calendar was adopted by England. As a result, records in Virginia during the 1600s and early 1700s such as land grants, wills, and court documents were written under the Julian calendar. It’s important that researchers analyzing primary resources of the Jamestown settlement records, for example, must account for the discrepancy in time between the calendar systems. 

The British Empire, including the American colonies, finally switched from the Julian to the Gregorian calendar in 1752. People who went to sleep on Wednesday September 2, 1752 woke up the next morning on Thursday September 14, 1752, in the Gregorian calendar. Moreover, the English previously celebrated the new year around the start of Spring on March 25, which they called “Lady Day” (AKA the Feast of the Annunciation of the Blessed Virgin). The Roman Empire recognized the first month as January—named after Janus, the god of beginnings and endings. The change to adopt January 1st as the New Year strongly affected how dates were recorded in colonial Virginia, leading some people to write both dates (dual dating) in documents such as ”1752/53.” Such a major change to the annual cycle surely caused some legal impacts, leading to adjustments, clarifications, and recalculations on contracts and certain deeds. In terms of genealogy research, some of the date discrepancies can be perpetuated if a person does not take into account the calendar change for a date before 1752. 

The modern Gregorian calendar is very accurate, but it still isn’t perfect. There is an error of about twenty-six seconds every year. The unaccounted time will not cause a disturbance in the short term, but after a span of nearly three thousand years the Gregorian calendar will be one day ahead of the solar year. The ancient Julian calendar is still useful, especially to astronomers as a simpler numbering system for understanding grander astrological timelines, reading ancient records, making predictions, and conducting simulations separate from the Earth year. It’s an interesting concept to grasp that throughout all of history and time the calendar system used today has only been widely accepted for less than three hundred years.