One of the most interesting conspiracy theories of all time got started when Heribert Illig noticed a rather odd discrepancy in the explanation of the Gregorian Calendar. The conspiracy theorists were certain that the Roman Catholic church had faked 300 years of history, and this became known as the Phantom Time Hypothesis. On the surface they had some compelling facts on their side.
In the 1500’s, the Roman Catholic church noticed that Easter was occurring later and later in the spring over the centuries. If something wasn’t done Easter was going to slide right into summer, and eventually the fall. Something had to be done.
The problem as it turned out was the Julian calendar. It didn’t calculate leap years very well and was putting more in than was required. So a new calendar system that did the calculations right was proposed. Instead of leap years occurring every four years, they would occur every four years except for years ending in 00 like 1300, 1400, 1500 and so on. That was actually too large a correction, so every four hundred years the new calendar would skip the skip…. meaning that when the century was divisible by 4, the leap year would not be skipped. So in 1600 it was a leap year after all. This stopped the drift, but by then Easter had slid a number of days. It would have to be put back where it belonged.
So in 1582 Pope Gregory XIII ordered the implementation of the Gregorian Calender. To put Easter back where it belonged he just shortened the year by 10 days. The last day of the Julian calendar was October 4, 1582 and the first day of the Gregorian calendar was October 15, 1582. As a result, Easter happened 10 days earlier the next year when compared to solar events like the spring equinox. This of course created havoc for historians because some countries adopted the Gregorian calendar right away and others waited. To correctly document historical events near the time of transition, the historian must determine which calendar the historical document is referring to.
But what set off the conspiracy theorists was the fact that 10 days wasn’t enough. If you count all the leap years that would have been different between the Julian calendar and the Gregorian, it would take thirteen days to fix the problem, not 10. What could the church have been up to? Why would they go to the trouble of doing all that math, get a new calendar that matches the solar calendar within a few seconds, but then mess up a really easy calculation like that? What were they trying to hide?
The theory went that the Roman Catholic church had just made up 300 years of history. One theory ran that one pope wanted to be the pope of record for 1000 AD, so he got there by advancing the calendar 300 years. Another theory ran that the church had created historical documents predicting future events, and when they didn’t happen they just made up the history to match the documents, stuck it in and claimed that the predictions had come true. Some researchers even went so far as to examine record keeping in certain places to see if there were gaps in building and road construction of 300 years and they found some.
But alas for the conspiracy theorists, Gregory got it right. Since his goal was to put Easter back where it belonged, he had to correct not to when the Julian calendar began, but to when the date of Easter was first adopted. That happened at the council of Nicaea in 325 AD. Since Gregory was certain that Constantine got it right in 325, there was no need to adjust by 13 days, only 10.
The conspiracy theorists were working from correct data. They just weren’t working from ALL the data.