Adoption of the Gregorian calendar liege lord, the King of Poland, it agreed in 1611 to do so. So 22 August was followed by 2 September 1612. However, this calendar change did not apply for other territories of the Hohenzollern, such as Berlin-based Brandenburg, a fief of the Holy Roman Empire. Through Ole Rømer's influence, Denmark in 1700, which then included Norway, adopted the solar portion of the Gregorian calendar with Sunday, 18 February 1700, being followed by Monday, 1 March 1700, simultaneously with the Brandenburg-Pomerania and other Protestant estates of the Holy Roman Empire. None of these states adopted the lunar portion, instead calculating
Roman calendar The unattested but almost certain lunar year and the pre-Julian civil year were 354 or 355 days long, with the difference from the solar year more or less corrected by an irregular intercalary month. The Julian year was 365 days long, with a leap day doubled in length every fourth year, almost equivalent to the present Gregorian system. The calendar era before and under the Roman kings is uncertain but dating by regnal years was common in antiquity. Under the Roman Republic, from 509, years were most commonly described in terms of their reigning ordinary consuls. (Temporary and honorary consuls