Adoption of the Gregorian calendar for secular use occurred in Eastern Orthodox countries as late as the 20th century and some religious groups in some of these countries still use the "old style" (O.S.) Julian calendar for ecclesiastical purposes. The Kingdom of Bulgaria changed from the Julian to the Gregorian calendar during the First World War on 31 March 1916, where the next day was 14 April 1916. The Ottoman Empire's Rumi calendar, used for fiscal purposes, was realigned from a Julian to a Gregorian starting on 16 February/ 1 March 1917. The beginning of the year was reset to 1 January starting in 1918.
Adoption of the Gregorian calendar The numbering of the years, though, remained uniquely Turkish until the Gregorian calendar was introduced for general purposes on 1 January 1927. In Russia, the Gregorian calendar was accepted after the October Revolution. On 24 January 1918 the Council of People's Commissars issued a decree that Wednesday, 31 January 1918, was to be followed by Thursday, 14 February 1918, thus dropping 13 days from the calendar. With the change, the October Revolution itself, once converted, took place on November 7. Articles about the October Revolution which mention this date difference tend to do a full conversion to the dates from