The years 850 to 880 are relevant for the question of a possible woman on the Pope's throne.
If there was Pope Johanna, she must have exercised her office during this period.
And it is precisely during this period that a whole series of questions arise, because there are ambiguities that may have been deliberately created to conceal facts.
Leo IV., pontificate 847-855, 8 years 3 months 7 days
Anastasius III. pontificate 855, 2 days; opponent to Benedict III.
Benedikt III., pontificate 855-858, 2 years 6 months 19 days
Nikolaus I., pontificate 858-867, 9 years 6 months 20 days
Hadrian II., Pontificate 867-872; Fourth Council of Constantinople (869-870)
John VIII., pontificate 872-882, 10 years 2 days; First pope who died by force since the persecution of Christians
There is no room in this list for a possible Popess.
There are various ambiguities and contradictions regarding the dates in the various sources.
Concerning the monograms the coins of the two Popes with the name Johannes are usually declared as variants of the same pope. The monogram was the binding signature for documents. If a pope had changed his monogram, all previously signed documents would have become invalid. This is not very plausible, especially with regard to the recognition of Louis II as Franconian Emperor. In this case Louis II would have been unconfirmed Emperor for about 16 years. In addition, there are clear stylistic differences between the two coins, which reinforces the untrustworthiness of this assertion even further.
The impression arises that a pontificate should have been covered up: The Pontificate of a woman.
The theologian Joan Morris assumes that Martin von Troppau had read the Liber Pontificalis. Because of the erasures he could no longer safely classify the pontificate of Joan of Arc. He started it directly after Leo IV and since then most scientists have followed this assumption.
After evaluating the available sources and including the information that can be obtained from the combination coins, the actual pontificates are documented as follows:
Leo IV: Taking office 847
not documented from 853 onwards. An exact date of death is indicated, but not the year.
Bendedict III. : inauguration 853?
Before 855 combination coin Benedikt III. with Lothar I.
Combination coin with Emperor Ludwig II and Pope Benedict. Ludwig II. inherited the imperial crown in summer 855.
According to sources, the death of Pope Benedict III can be assumed after late autumn 855. He can only be proved until November 855.
Johannes Anglicus: Taking office 856
The sacred coronation of Louis II by Pope John is documented. There is a letter from Anastasius to Pope John. In addition, combination coins show Ludwig II and Pope John
857/58 Death of Johannes Anglicus?
Nikolaus I: Inauguration 858
After 858 combination coins Louis II with Nikolaus
867 Death of Pope Nicholas.
Hadrian II: Inauguration 867
Combination coin Louis II with Hadrian
872 Death of Pope Hadrian II.
John VIII: Taking office 872
875 Death of Emperor Louis II His successor is Charles II the Bald
After 875 combination coins of Charles II and John VIII
Pope John VIII is murdered in 882.
The coins of that time show no year and can therefore only be classified into a time window by the style and the combination of the names of pope and emperor.
Text sources and sequence of coins confirm each other and testify that there was a female pope - Pope Joan -. This person is documented as John Anglicus, who had chosen the pope name John and was the eighth pope of that name in the census.
Figure «Lateran Palace and Lateran Basilica»: Dnalor 01 - Own work, CC BY-SA 3.0, Link