How did the Gregorian calendar’s usage spread across the globe and not have inconsistencies in different areas from initial misinformation?

Question

In the early days of the calendar how can we be so sure that written records like journal entries are correctly dated?

In: Other

Answer 1

The Gregorian calendar was initially adopted in October 1582 with a jump of 10 days from the Julan calendar. It was because of a papal bull by Pope Gregory XIII hence the name
That occurred in Spain, Portugal, France, Poland, Italy, Catholic Low Countries, Luxemburg, and colonies. The last change too if tom the Julan calendar was in the early 20th century when Orthodoxy Christian countries in easten Europe changed, Greece was last and changed in 1923.
Other countries changes during the period in-between.
The change is because of the drift on the equinox and therefore the season in the Julian calendar. It is based on exact observation of the sky and the Gregorian Tower that was an observatory was created for it and continues to this day with a modern telescope now located in Arizona because of better observation conditions.

The church has always been interested in astronomical observation in part because easter is defined as the first Sunday after the first full moon that falls on or after the equinox.

So the adaptation is relatively late and based on a change of a previous system. So you have organized governmental and church structures.
There likey was a lot of confusion because everyone did not change at once. Countries did not exist the same way so and in what is today Germany it was a 120 year period where the part that was Catholic and the part that was protestant use different system,
So confusion existed but it was if Gregorian or Julian calendar was used.