The process of adoption took place over a period of about 350 years.

So, for more than three centuries after 1582 there were two calendars in use in Western countries.

cultures also developed their own intricate calendars; the ancient Maya had two separate years—the 260-day Sacred Round, and the 365-day Vague Year, the latter of which is also similar to the modern-day Gregorian calendar. The Romans used two different year lengths; the older one had 304 days divided into 10 months; the newer 365 days divided into 12 months; very much like the modern calendar.

History of calendar dating video

The Vague Year of 365 days is similar to our modern calendar, consisting of 18 months of 20 days each, with an unlucky five day period at the end.

The Vague Year had to do primarily with the seasons and agriculture, and was based on the solar cycle.

The calendar can show how a particular day can have different dates in different countries.

For example, the Great Fire of London started on 1666 September 2 (see Pepys' Diary), Julian day number 2329809.

By 1000 AD, European countries had generally adopted the Julian calendar of 365 days in a year and 366 days every fourth year.

The Julian calendar did however accumulate errors at a rate of roughly one day every hundred years when compared to astronomical events.The Russian revolutionaries captured the seat of government in Petrograd on 1917 October 25 according to their calendar, which was still the Julian calendar.The news reached the USA the next day, which was November 8, since the USA was using the Gregorian calendar.Here is an historical calendar for the years 1000 to 2100. The calendar in use for a particular year varied from country to country for many centuries.So having selected the year, choose from among 13 countries using the drop down menu on the top right of the calendar.To correct this, the Gregorian calendar was introduced by Papal decree in 1582, when ten days were dropped, so that September 4 was followed by September 15.