A fun bit of trivia is that it wasn't until the middle of the 18th century that it became standard in Europe to start the new year on January 1. Up until that point many regions used March 25 as the date of the New Year. So, for example the day March 24, 1715 would have been followed by March 25, 1716.
March 25 was the Feast of the Annunciation whereas January 1 was the Feast of the Circumcision, so the two dating methods were called Annunciation Style and Circumcision Style.
Obviously this created some ambiguity since the Circumcision Style date March 24, 1716 would be rendered March 24, 1715 when written Annunciation Style. Around the time of the transition to Annunciation Style dating in Britain you actually see people writing both dates together to avoid confusion, usually with the Circumcision Style date below the Annunciation Style date. (You can see an example here: https://upload.wikimedia.org/wikipedia/commons/3/3b/Memorial...)
Oh, is that why Tolkien had Frodo throw the Ring in the Fire on March 25? And then King Elessar made that day the first day of the New Year. And the tradition held on until the 18th century. Huh.
March 25 was the Feast of the Annunciation whereas January 1 was the Feast of the Circumcision, so the two dating methods were called Annunciation Style and Circumcision Style.
Obviously this created some ambiguity since the Circumcision Style date March 24, 1716 would be rendered March 24, 1715 when written Annunciation Style. Around the time of the transition to Annunciation Style dating in Britain you actually see people writing both dates together to avoid confusion, usually with the Circumcision Style date below the Annunciation Style date. (You can see an example here: https://upload.wikimedia.org/wikipedia/commons/3/3b/Memorial...)