History Of Gregorian Calendar. Eventually all of europe, as late as 1918 in the case of russia, adopted the gregorian calendar. The gregorian calendar was a further improvement and has been almost universally adopted because it satisfactorily draws into one system the dating of religious festivals based on the phases of the moon and seasonal.
In 1582, pope gregory xiii reformatted the julian calendar. The gregorian calendar was introduced in 1582 by pope gregory xiii to reform the previous julian calendar, which had become misaligned with the seasons.