Gregorian calendar It also specifies its epact relative to 1 January, in contrast with the Julian calendar, which specified it relative to 22 March. The old date was derived from the Greek system: the earlier "Supputatio Romana" specified it relative to 1 January. During the period between 1582, when the first countries adopted the Gregorian calendar, and 1923, when the last European country adopted it, it was often necessary to indicate the date of some event in both the Julian calendar and in the Gregorian calendar, for example, "10/21 February 1750/51", where the dual year accounts for some countries already beginning their
Adoption of the Gregorian calendar Japan decided to officially replace its traditional lunisolar calendar with the Gregorian calendar in 1872, so the day following the second day of the twelfth month of the fifth year of the Meiji emperor's rule, became . (The Japanese rendering of the Western months is simply "ichi-gatsu" or "One-month" for January, "ni-gatsu" or "Two-month" for February, etc.) This brought Japan's calendar in alignment with that of the major Western powers (excluding Russia). To this day, however, it is common to use Nengo, reign names instead of the Common Era or Anno Domini system, especially for official documents; for instance, "Meiji"