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Pinning Down the Date:
New Style/Old Style and the Calendar Question

You may notice, as you are researching the Pilgrims, certain puzzling discrepancies in dates.

For instance, Mourt’s Relation, a primary source account of the landing of the Pilgrims at Plymouth, reads
10th of December. On the Sabbath day we rested; and on Monday we sounded the harbor, and found it a very good harbor for our shipping. We marched also into the land, and found divers cornfields, and little running brooks, a place very good for situation.

This seems straightforward enough: on Sunday, December 10th, 1620, the exploring party rested. On Monday, December 11th, they landed at Plymouth.

And yet, the Pilgrim Society annually celebrates the landing (as Forefathers Day) on December 21st. Why the difference?

The answer lies both in science and in politics. The Julian calendar (established by Julius Caesar) was slightly out of sync with the actual cycle of the physical world. Every year, the Julian calendar was "off" by 11 minutes and 15 seconds. Over the course of centuries, the manmade calendar and the natural calendar grew further apart. By 1582, the difference had grown to 10 days. In that year, Pope Gregory XIII promulgated a new calendar to bring the manmade calendar back into sync with the actual physical progression of time. The Catholic countries of Europe followed Gregory’s lead immediately. For intermingled reasons of politics and religion, England and her colonies did not change their calendar until 1752.

The result of these calendar systems is a dual system of dating, known as "Old Style/New Style." Hence, you may occasionally see a date, such as the date of the Pilgrims landing, referred to as "December 11/21."

And if that alone is not complicated enough, did you know that the Pilgrims regarded March 25th as the beginning of the new calendar year? You will therefore sometimes see dates in January, February and March referred to by two years (such as 1622/23). The first year is the year as computed by the Pilgrims. The second year is the year as computed by the modern calendar.

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