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Monarch: Regnal Year: Calculate Christian Year
Since the ecclesiastical calendar is based on lunar rather than solar cycles, certain key holidays (feasts) occur on different days each year. The method of calculating these feasts has also changed since the council of Nicea (325 A.D.). The button labeled "Calculate Holidays" calculates the dates of seven major feasts for the year entered in the field labeled "Year", and displays the results below this field. The only restrictions are that the number entered in the field "Year" must be an integer (no fractions) greater than zero. However, the holidays generated are only valid for dates since 325 A.D. (Early Christian and Roman dating is another story). Also, for purposes of calculation, I have assumed that the ecclesiastical year begins on January first, even though this standard was only gradually accepted. If you are working with early monastic documents you might want to consider that dates from December 25th through March may be "off" by one year. To a Benedictine, for instance (to whom the year began on December 25th), the feast of the Innocents in 1450 would be December 28th, 1450, while to others it might be December 28th, 1449. In fact, before 1582, most calendars did not have the year begin on January 1st, even though the calculation of the moveable feasts acted as if it did. In England, the year "began" either on December 25th, or, more frequently on March 25th (Lady Day), until 1752. These vagaries are not something I wanted to include in the calculations, since they often varied quite a bit. The calculations for the holidays will take into account the days dropped from the calendar when the "New style" was adopted, since these affect the month and day of Easter. Conventions about the beginning of the year are easily corrected for.
Here is a more detailed description of the transition year (in England): 1752.
The area called "Old and New Style Dates" converts the old style date to a new style date and returns an answer.
Remember that these forms assume that the year begins on March 25th. If you want to plug in dates derived from the "Ecclesiastical Holidays" page, be aware that you will have to subtract 1 from the year for all dates between January 1st and March 24th.
Of course to someone on the continent, the day that an as-yet-to-be-completely-reformed English person called Febryart 29,1752 would correspond to March 11, 1752.
Remember that leap years are calculated by the ecclesiastical year and not the civil year.
Double years such as 1324/5 reflect Old Style dating. While the so-called 'Christian year' began on January 1, the legal year began on March 25. For example, January 1 in Elizabeth I's 1st regnal year occurred in the Christian year1559, but legally the year was still 1558, and would be until March 25. From January 1 to March 24, the convention is to note both years with a slash between them, e.g. '1558/9.'
Keep in mind that a monarch's last regnal year is cut short by death or deposition and may not include all dates.
Also, remember that while the so-called "Christian year" began on January 1, the legal year began on March 25. For example, January 1 in Elizabeth I's 1st regnal year occurred in the Christian year1559, but legally the year was still 1558, and would be until March 25. From January 1 to March 24, the convention is to note both years with a slash between them, e.g. "1558/9."
Remember also that from 1582 through 1752, English dates (Old Style) will not correspond with Continental dates.