The Calendar and its Reforms

By Edwin C. Dunn

The calendar is a man-made device for reckoning time. Through the centuries calendars have been altered more closely to represent the seasons of the year, the phases of the moon, and the solar year. These changes must be recognized and understood in order to accurately date past events in relation to our own time and calendar.

In Assyria and other areas of the ancient Middle East, the month was based on phases of the moon. This required adjustments of the calendar from time to time. The addition of an extra month in seven of every 19 years is still the basis for the religious calendar of the Jews. Mohammed forbade shifting from a 12-month calendar to a 13-month calendar, so the Islamic religious calendar still consists of a lunar year of 354 days. The result is that Islamic religious festivals shift through all the seasons of the year three times per century.

The Romans were superstitious and believed that even numbers were unlucky, so their months were 29 or 31 days long, except for February which had 28 days. The earliest Latin calendar only had ten months, but even with twelve months, the year would only have had 355 days. The Romans inserted a month called Mercedonius, consisting of 22 or 23 days, every second year.

The first reform of the pagan calendar in Europe was in 45 BC by Julius Caesar, with further reforms in 8 BC by Caesar Augustus, the first Roman emperor and successor of Julius Caesar. Even with Mercedonius, it had been found that the seasons had shifted about two months from where they should be on the calendar. One year was made 445 days long by an imperial decree. Then he made the solar year (365 days and 6 hours) the basis of the calendar, with 12 months consisting of 30 or 31 days, except for February, and an additional day every four years to take care of the six hours. Thus was born the Julian calendar which is still used by the Eastern Orthodox churches.

The year, or the numbering of months, originally began in March, as is evidenced by the terms September (septem, Latin for 7), October (octo, Latin for 8), November (novem, Latin for 9), and December (decem, Latin for 10), names which we still use in our calendar today. Julius Caesar changed the month Quintilis (quinque, Latin for five) to Julius (July) after himself, and Sextilis (sex, Latin for six) became Augustus (August). Sometimes, in our research, September thru December are found written as: 7ber, 8ber, 9ber, 10ber, referring to the old Julian calendar. It should not be confused with the present 7th to 10th months (July to October) of our calendar year.

January and February were added to the old Latin calendar to make twelve months in the solar year. January was named after Janus, protector of the gateway to heaven; February was named after Februalia, a time period when sacrifices were made to atone for sins. March was named after Mars, the god of war, presumably indicating that the campaigns interrupted by winter could resume. April is from the Latin, aperire, to open (buds). May is named after Maia, the goddess of growth of plants, and June is from juvenis, the Latin for youth.

The Romans gave one day of the week to each planet known to them, considering the sun and moon as planets.  The modern names of the days of the week are based either on the Latin names (French, Italian, Spanish), or on the Saxon translations (English, German), with a few exceptions. Thus, in Latin we have: Dies Solis (Sun), Dies Lunae (Moon), Dies Martis (Mars), Dies Mercurii (Mercury), Dies Jovis (Jupiter), Dies Veneris (Venus), Dies Saturni (Saturn). In Spanish, these became domingo, lunes, martes, miercoles, jueves, viernes, and sabado.

In Saxon, Tiw was substituted for Mars, Woden (Wotan) for Mercury, Thor for Jupiter (Jove), Frigg for Venus, and Saterne for Saturn, so in English we have the five weekdays named for Saxon gods, rather than Roman. In German, the days of the week follow the Saxon pattern, except for Mittwoch (Middle of the Week) in place of Woden's Day, and Sonnabend (Sunday's Eve) in place of Seterne's Day.

After 1500 years of using the Julian calendar, people began to realize that the vernal equinox, a fact of nature, had shifted from 21 March to 11 March, and the calculations of Easter had been thrown off. It was determined by that time that the solar year (the time it took for the earth to make one complete circumference of the sun) was, in fact, 365 days, 6 hours, and 11 minutes. This additional 11 minutes added up to 8 days in 1000 years, and the seasons were slowly moving backward relative to the calendar being used. This problem was brought to the attention of Pope Clement IV (1265-1268) but not until Pope Gregory XIII (1572-1585) was anything done about it.

Gregory XIII ordered in 1582 that ten days be dropped from the calendar, whereby 5 October 1582 became 15 October 1582, restoring the vernal equinox to 21 March. Furthermore, he ordered that in every 400 years leap year's extra day should be omitted three times. This was accomplished by omitting it on centennial years of which the first two digits could not be divided by four without a remainder. Thus, it was omitted in 1700, 1800, and 1900, but will not be omitted in 2000. This took care of a discrepancy of 29 seconds in the solar year which would add up to 29 hours every 4000 years. His decree also changed the beginning of the year from 25 March to 1 January. That made obsolete the meaning of the old Latin number-named months on the calendar. This became known as the Gregorian calendar and is the calendar we use today.

It was not so easy to get this calendar adopted by all countries, however. All Roman Catholic countries adopted the new system, but England (remember that the Protestant Queen Elizabeth I was on the throne following all the troubles that her father, Henry VIII, had had with Rome), and its colonies, refused to adopt the new calendar until 1752. Then, by Act of Parliament, eleven days were to be omitted after 2 September 1752, with the following day being 14 September 1752. The year 1751 was shortened by three months due to the change of the beginning of the year from 25 March to 1 January. In other words, 1751 began on 25 March while 1752, the following year, began on 1 January. If you have Russian or Turkish ancestry, those countries did not adopt the Gregorian calendar until the twentieth century.

In spite of the political differences, many people began before 1752 to use the Gregorian system. Between 1582 and 1752, you will frequently find a system of double dates, eg. 3 March 1655/56, which indicated that while it was still officially 1655, some people considered it to be 1656. This double dating, of course, only affected dates between 1 January (the new New Year's) and 25 March (the old New Year's). Thus, when Governor Winthrop wrote a letter to his wife dated 22 March 1629, and another dated 28 March 1630, only six days had passed. George Washington, who was born on 11 February 1732, changed his birthday to 22 February after the calendar change so he could celebrate his birthday at exactly a one year interval.

If the gravestone of your ancestor indicates that he died August 31, 1810, aged 81 years, 6 months, 19 days, you might determine that he was born 12 February 1729, but in fact he was born 1 February 1729 according to the then-used calendar. These differences in dates can be designated as Old Style (O.S.) and New Style (N.S.) without actually making the conversion. If you find that John and Mary Smith had a son born 27 March 1640 and a daughter born 28 February 1640, remember that 28 February 1640 was Old Style and was actually 1641 by our reckoning.

In the 17th century, the Puritans and Quakers would not use the "pagan" names of the months, and so designated the month by a numeral, usually with the day preceding the month, but not always. Thus, 16th, 2nd month, 1644 was 16 April 1644, not 16 February 1644, and 3:12:1639 represents 3 February 1640 (New Style), not 3 December 1639.

Events were often dated in the Middle Ages by the use of the regnal years, or by the number of days before or after the nearest church festival or fast. A regnal year designated the year of a monarch's reign. The regnal year began on the date of his or her accession, which was, of course, different for each sovereign. Thus, in England, you might find a document dated 5 January 3 Henry VI, meaning the third year of the reign of Henry VI, or 5 January 1424 (or 1425 by our reckoning) (his reign began on 1 September 1422). The reign of Charles II (who literally lost his head, but not from unraveling calendrical dates) began on 30 Jan. 1648 (or 1649 N.S.). Often a regnal year was accompanied alongside by the calendar year. After the Restoration of the monarchy in 1660, most documents will bear the Anno Domini year, but even into the present century Acts of Parliament have born the regnal year. Many court records (wills, deeds) in the American colonial period bear the year of the reigning sovereign, along with the calendar date, a fact which we usually ignore.

The church festivals used to date events were extremely numerous, so that almost every day could be related to some church celebration. Fast days often preceded a festival.  Charts are available to coordinate these church festivals to a modern calendar date. Some feasts were movable, however, such as Easter. This date was fixed by the Council of Nicea in 325 AD, as falling on the first Sunday after the full moon which occurs on or next after the vernal equinox (March 21). Charts are available which show on which day of the particular year Easter may have fallen over the past centuries. Other movable feasts, such as Ash Wednesday, Ascension Day, etc., are governed by that of Easter.

If you have oriental ancestry, we'll leave an explanation of the Chinese, Buddhist, and Hindu calendars for experts in those fields.

It should be obvious after this brief history that a date on a document must be interpreted in light of the time period, the religious affiliation, and the country where it was created, before it can be compared to our modern reckoning of time and the Gregorian calendar we use today.

This page was last updated on: January 19, 2020