Oct 4th - Last Julian calender day in Spain/Portugal/pontifical states
Oct 5th - Gregorian calendar introduced in Italy, other Catholic countries
Oct 15th - Many Catholic countries switch to Gregorian calendar, skip 10 days
Dec 10th - France begins use of Gregorian calendar
Dec 14th - Zealand/Brabant Neth adopt Gregorian calendar, tomorrow is 12/25
Dec 15th - Spanish Netherlands/Denmark/Norway adopt Gregorian calendar
Dec 21st - Flanders adopts Gregorian calendar, tomorrow is Jan 1 1583
1584:
Jan 7th - Last day of the Julian calendar in Bohemia & Holy Roman empire
Jan 17th - Bohemia adopts Gregorian calendar
Jan 22nd - Parts of Switzerland adopt Gregorian calendar (& parts in 1812)