By the ninth century, parts of southern Europe began observing first day of the new year on March 25 to coincide with Annunciation Day (the church holiday nine months prior to Christmas celebrating the Angel Gabriel's revelation to the Virgin Mary that she was to be the mother of the Messiah). However, England did not adopt this change in the beginning of the new year until late in the twelfth century.
Because the year began in March, records referring to the "first month" pertain to March; to the second month pertain to April, etc., so that "the 19th of the 12th month" would be February 19.
Today, Americans are used to a calendar with a "year" based the earth's rotation around the sun, with "months" having no relationship to the cycles of the moon and New Years Day falling on January 1.
However, that system was not adopted in England and its colonies until 1752.
In general, double dating was more common in civil than church and ecclesiastical records.
In accordance with a 1750 act of Parliament, England and its colonies changed calendars in 1752.
To avoid misinterpretation, both the "Old Style" and "New Style" year was often used in English and colonial records for dates falling between the new New Year (January 1) and old New Year (March 25), a system known as "double dating." Such dates are usually identified by a slash mark [/] breaking the "Old Style" and "New Style" year, for example, March 19, 1631/2.
Occasionally, writers would express the double date with a hyphen, for example, March 19, 1631-32.
January 1 was established as the first day of the new year.
Protestant countries, including England and its colonies, not recognizing the authority of the Pope, continued to use the Julian Calendar.