On Sun, Jul 14, 2024 at 5:25 PM Marc Donner <marc.donner@gmail.com> wrote:

Note that the switch to the Gregorian calendar happened at different times in different countries. In Catholic-dominated countries it happened in October of 1582. The English-speaking world, being Protestant-dominated, waited until September of 1752 to adopt it.

And Russia didn't adopt the Gregorian calendar until 1918. IIRC the Eastern Orthodox churches still use the Julian calendar for scheduling ecclesiastical events such as the date of Easter.

-Paul W.