No, the conspiracy suggests that the leaders of the major powers in Europe in the year 700-and-something conspired to simply start calling it the year 1000 for the prestige value, without recording this decision anywhere. Essentially it's like we all agreed tomorrow to start calling next year 2300 instead of 2023 (but theoretically slightly more plausible in a time before centralized calendars and computing).
Later historians simply took the official date for granted - so the people in Pope Gregory's time believed they were living in the year 1582, but, unbenknownst to them, only 1285 years had passed since the year 1CE. The real date was reflected in their astronomical calculations, leading to the 10 day correction instead of a 13-day one.
Of course, this is all absurd for all the reasons listed in the article, and others.
It's not that absurd to believe mistakes could have been made there. The BC/AD system was invented centuries after Christ and only started to become actually known around the 730s:
The addition of the B.C. component happened two centuries after Dionysius, when the Venerable Bede of Northumbria published his "Ecclesiastical History of the English People" in 731, wrote Antonia Gransden, who was a reader in history at the University of Nottingham, in her book "Historical Writing in England: c. 500 to c. 1307" (Routledge, 1997). The work brought the A.D. system to the attention of more people and expanded it to include years before A.D. 1. Prior years were numbered to count backward to indicate the number of years an event had occurred "before Christ" or "B.C.
The B.C./A.D. system became more popular in the ninth century after Holy Roman Emperor Charlemagne adopted the system for dating acts of government throughout Europe."
Before the adoption of this system dating was rather chaotic, with dates usually being recorded as "year X of the reign of so-and-so". To line dates up and synchronize them on a timeline was difficult, and synchronization of European, Islamic, Greek and Roman history wasn't even attempted until the 16th century (Scaliger's De Emendatione Temporum).
Mistakes, yes. 300 years? No. 300 years, including the Carolingian Dynasty, the expansion of Islam (i.e. The Battle of Tours), the Norse expansion (eventually leading to the domination of Europe by a bunch of guys named Norman)? Nope, no so much. And that's before you start looking at Islamic, Indian, and Asian data.
And then there's radiometric dating and dendrochronology, which are chaotic in their own right, but 300 years? Nah.
Weirdly, I was just reading Lynn White's Medieval technology and social change (1966), discussing the introduction of the stirrup and the heavy plow (as opposed to the scratch plow), both of which happened in this period. There's little in the way of good dates, but some very big changes such as the move from individual family subsistence farms to large, ridge-and-furrow strips and Charles Martel's redistribution of church lands to his followers, introducing true heavy cavalry and the feudal system. (Note: may be a bit out of date with modern research.)
This comment has me wondering about how software could help sort through timelines like this. Given a corpus of historical periodicals referencing individuals and entities, sort them in order by date. Surely this has been / is being done? I searched for "automated historiography" but didn't find anything resembling that.
In some ways, it might be easier to pull off with centralized digital calendars, as long as the powers-that-be have access to commonly-used NTP servers. (Which could certainly accelerate the Y2038 problem!)
Globally centralized timekeeping could certainly make for an interesting premise to a dystopian sci-fi novel. Time really does fly when the Fed controls the NTP root nodes.
Later historians simply took the official date for granted - so the people in Pope Gregory's time believed they were living in the year 1582, but, unbenknownst to them, only 1285 years had passed since the year 1CE. The real date was reflected in their astronomical calculations, leading to the 10 day correction instead of a 13-day one.
Of course, this is all absurd for all the reasons listed in the article, and others.