Editing Anno Domini (section)

===New year===
{{Further|New Year}}

When the reckoning from Jesus' incarnation began replacing the previous dating systems in western Europe, various people chose different Christian feast days to begin the year: Christmas, [[Annunciation]], or Easter. Thus, depending on the time and place, the year number changed on different days in the year, which created slightly different styles in chronology:<ref>[[C. R. Cheney]], [http://catdir.loc.gov/catdir/samples/cam032/99027383.pdf ''A Handbook of Dates, for students of British history''] {{Webarchive|url=https://web.archive.org/web/20151205104025/http://catdir.loc.gov/catdir/samples/cam032/99027383.pdf |date=5 December 2015 }}, Cambridge University Press, 1945–2000, pp. 8–14.</ref>
* From 25 March 753 [[Ab urbe condita|AUC]] (1 BC), i.e., notionally from the incarnation of Jesus. That first "Annunciation style" appeared in [[Arles]] at the end of the 9th century then spread to Burgundy and northern Italy. It was not commonly used and was called ''calculus pisanus'' since it was adopted in [[Pisa]] and survived there until 1750.
* From 25 December 753 AUC (1 BC), i.e., notionally from the birth of Jesus. It was called "Nativity style" and had been spread by Bede together with the ''anno Domini'' in the early Middle Ages. That reckoning of the Year of Grace from Christmas was used in France, England and most of western Europe (except Spain) until the 12th century (when it was replaced by Annunciation style) and in Germany until the second quarter of the 13th century.
* From 25 March 754 AUC (AD 1). That second "Annunciation style" may have originated in [[Fleury Abbey]] in the early 11th century, but it was spread by the Cistercians. [[Florence]] adopted that style in opposition to that of Pisa, so it got the name of ''calculus florentinus''. It soon spread in France and also in England where it became common in the late 12th century and lasted until 1752.
* From Easter. That ''mos gallicanus'' (French custom) bound to a [[moveable feast]] was introduced in France by king [[Philip II of France|Philip Augustus]] (r. 1180–1223), maybe to establish a new style in the provinces reconquered from England. However, it never spread beyond the ruling élite.
With these various styles, the same day could, in some cases, be dated in 1099, 1100 or 1101.