Adoption of the Gregorian calendar begins, eventually leading to near-universal adoption.

The adoption of the Gregorian Calendar has taken place in the history of most cultures and societies around the world, marking a change from one of various traditional dating systems to the contemporary system – the Gregorian Calendar – which is widely used around the world today. Some polities adopted the new calendar in 1582, others not before the early twentieth century, and others at various dates between.

A few have yet to do so, but except for these, the Gregorian Calendar is now the universal civil calendar, yet old style calendars remain in use in religious or traditional contexts. During – and for some time after – the transition between systems, it has been common to use the terms "Old Style" and "New Style" in dating to indicate which calendar was used to reckon them.

Reforma Gregoriana del Calendario Juliano
Reforma Gregoriana del Calendario Juliano (Source: Wikimedia Commons)
William Hogarth 028
William Hogarth 028 (Source: Wikimedia Commons)
Almanacka 1753
Almanacka 1753 (Source: Wikimedia Commons)
Gravestones with Hijri and Gregorian dates Ferikoy Cemetery Istanbul 2024
Gravestones with Hijri and Gregorian dates Ferikoy Cemetery Istanbul 2024 (Source: Wikimedia Commons)

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From the Historical History channel.

Sources and further reading: Wikipedia — Adoption of the Gregorian calendar (CC BY-SA). Images: Wikimedia Commons.