<P> 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 the date of Easter astronomically using the instant of the vernal equinox and the full moon according to Kepler's Rudolphine Tables of 1627; this combination was referred to by the Protestant estates as the "improved calendar" (Verbesserte Kalender) and considered to be distinct from the Gregorian . They finally adopted the Gregorian calculation of Easter in 1774 . The remaining provinces of the Dutch Republic adopted the Gregorian calendar on 12 July 1700 (Gelderland), 12 December 1700 (Overijssel and Utrecht), 12 January 1701 (Friesland and Groningen) and 12 May 1701 (Drenthe). </P> <P> Sweden's transition to the Gregorian calendar was difficult and protracted . Sweden started to make the change from the Julian calendar and towards the Gregorian calendar in 1700, but it was decided to make the (then 11 - day) adjustment gradually by excluding the leap days (29 February) from each of 11 successive leap years, 1700 to 1740 . Meanwhile, the Swedish calendar would be out of step with both the Julian calendar and the Gregorian calendar for 40 years; also, the difference would not be constant but would change every four years . This system had potential for confusion when working out the dates of Swedish events in this 40 - year period . To add to the confusion, the system was poorly administered, and the leap days that should have been excluded in 1704 and 1708 were not excluded . The Swedish calendar (according to the transition plan) should have been 8 days behind the Gregorian but was 10 days behind . King Charles XII recognised that the gradual change to the new system was not working, and he abandoned it . Rather than proceeding directly to the Gregorian calendar, it was decided to revert to the Julian calendar . This was achieved by introducing the unique date 30 February in 1712, adjusting the discrepancy in the calendars from 10 back to 11 days . Sweden finally adopted the solar portion of the Gregorian calendar in 1753, when Wednesday, 17 February, was followed by Thursday, 1 March . Since Finland was under Swedish rule at that time, it did the same . The Russian Empire's 1809 conquest of Finland did not revert this, since autonomy was granted, but government documents in Finland were dated in both the Julian and Gregorian styles . This practice ended when independence was gained in 1917 . </P> <P> Through enactment of the Calendar (New Style) Act 1750, Great Britain and its colonies (including the eastern part of what is now the United States) adopted the Gregorian calendar in 1752, by which time it was necessary to correct by 11 days . Wednesday, 2 September 1752, was followed by Thursday, 14 September 1752 . Claims that rioters demanded "Give us our eleven days" grew out of a misinterpretation of a painting by William Hogarth . In Great Britain, the term "New Style" was used for the calendar and the Act omits any acknowledgement of Pope Gregory: the Annexe to the Act established a computation for the date of Easter that achieved the same result as Gregory's rules, without actually referring to him . </P> <P> With the same Act, the Empire (except Scotland, which had already done so from 1600) changed the start of the civil year from 5 April to 1 January . Consequently, the custom of dual dating (giving a date in both old and new styles) can refer to the Julian / Gregorian calendar change, or to the start of year change, or to both . </P>

When did the united states adopt the gregorian calendar