Adoption of the Gregorian calendar Julian to the Gregorian calendar. For example, in the article "The October (November) Revolution" the "Encyclopædia Britannica" uses the format of "25 October (7 November, New Style)" to describe the date of the start of the revolution. Other countries of eastern Europe, most notably Eastern Orthodox countries, adopted the Gregorian calendar in the 1910s or early 1920s. The last country of Eastern Orthodox Europe to adopt the Gregorian calendar for civil purposes was Greece, at the time under military administration following the 11 September 1922 Revolution, with Wednesday 15 February 1923 being followed by Thursday 1 March 1923. The Soviet
Adoption of the Gregorian calendar confusion, the system was poorly administered, and the leap days that should have been excluded in 1704 and 1708 were not excluded. The Swedish calendar (according to the transition plan) should have been 8 days behind the Gregorian but was 10 days behind. King Charles XII recognised that the gradual change to the new system was not working, and he abandoned it. Rather than proceeding directly to the Gregorian calendar, it was decided to revert to the Julian calendar. This was achieved by introducing the unique date 30 February in 1712, adjusting the discrepancy in the calendars from 10 back