What calendar reform moved New Year's Day from March 25 to January 1 in England in 1752?

The Gregorian calendar reform moved New Year's Day from March 25 to January 1 in England in 1752.

England and its colonies adopted the Gregorian calendar in 1752, replacing the Julian calendar for civil dating. The change corrected the Julian calendar's accumulated drift against the seasonal year by removing ten calendar dates and adopting a revised leap-year rule.

Before the reform, England traditionally treated March 25, the Feast of the Annunciation, as the start of the legal year, even though January 1 was often observed as a customary new year. The reform made January 1 the official beginning of the year as well.

The change caused apparent date complications in historical records. Dates from January 1 through March 24 can appear with two years in documents written under the old system, which is why historians sometimes use “Old Style” and “New Style” dating.