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 12 days, only 11 were skipped, and the day of the week was repeated on successive days, because at the same time the International Date Line was moved, from following Alaska's eastern border with Canada to following its new western border, now with Russia. Many of the countries of eastern Europe were Eastern Orthodox or Islamic and adopted the Gregorian calendar much later than western Christian countries. Roman Catholic countries such as the Polish–Lithuanian Commonwealth adopted the "new style" (N.S.) Gregorian calendar in 1582 (switched back in 1795 after Third Partition of Poland), but the switch to the Gregorian calendar