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The Letters of Pope Gregory VII - pilot project

posted on 19.08.2020, 07:14 by Tom Stafford, Charles West, George Litchfield

This data was created as part of a project studying the Register of Pope Gregory VII (d. 1085), funded by the Department of History at the University of Sheffield over the summer of 2020. The data was collected and analysed by George Litchfield with the assistance of Tom Stafford and Charles West. There is a CSV dataset, a project readme.txt and a project description, as well as numerous data visualisations.


During the process of collecting this data, we discovered a likely mistake in the German historian Caspar’s 1920’s edited version of the register, which has then subsequently been carried across to Cowdrey’s translation, and the wider historiography. From Book 4 letter 13 to 15, in early March 1077, Gregory is stated to be in Carpineto. However, on the 21st and 23rd of March, Gregory is stated to be in Carpi and Bianello respectively, both of which are over 500km away from Carpineto Romano according to Google maps. It is therefore more likely that in March 1077 Gregory was in Carpineti, which is only around 50km away from both Carpi and Bianello. These same entries may also shed light on Gregory’s travels and travel more widely at this time. On the 21st of March, two letters are recorded, issued from different locations. The first, letter 16, is written from Carpi, while the other entry is written from Bianello. These locations are approximately 44km apart, and so may show us the distance Gregory and other messengers could cover per day (another instance of this occurs in Book 3 letter 3).

The disorganisation of the register as it approaches its book 9 is well known, which suggests that the declining number of letters was another symptom of disorganisation in the papal chancery. However, while the data does show the overall trend of letters declining from 1074 to 1084, the average amount of words per letter generally increases over the course of his pontificate, with the exception of downward spikes towards 1082 and 1084, although the lack of entries for these years may be the cause of this. It could be suggested that though Gregory’s output really did decrease, rather than being purely a result of disorganisation, Gregory was simply trying to get more done in fewer letters.

The data suggests that time of year was taken into account when deciding when to send letters. This is not immediately clear from the coloured mapping of letters by season. However, by looking at the average distance letters covered by month, it can clearly be seen that in the months of March, April and May, letters covered a greater distance than other months, especially the winter months of January and February. This could be said to show Gregory’s consideration of the weather and travel conditions when conducting business. One thing that may seem strange is the fact that the extremity locations such as in England and Norway were sent in the winter; presumably this was to enable them to complete the more dangerous and remote legs of their journey in the summer.

Another notable set of results involving the month of sending is seen when the number of letters sent in each individual month is examined. Gregory’s correspondence tended to spike around April. This trend may be due to Easter, which would have been an important time for Gregory, and is also when he held a number of councils. This adds another important consideration into the mix when examining factors that influenced Gregory’s correspondence through letters.

The superimposing of Roman roads onto a map of Gregory’s letters also help us visualise an aspect of his pontificate. As would be expected, the overwhelming majority of Gregory’s letters are sent to areas part of the old Roman Empire. However, this visualisation also neatly demonstrates that Gregory wasn’t limiting his diplomacy to just the old Roman Empire, and sought to bring influence of the Roman areas where this was perhaps lesser felt, especially the northern areas of eastern Europe.

The extent of this communication becomes even more notable if we look at the most commonly written-to individual locations in the register. Bohemia and Hungary are first and sixth most written-to locations in the register. Although counting another region like Italy’s letters as a whole would result in a larger number, the letters to Bohemia and Hungary are highly concentrated on a specific group of people, whereas there would be larger variety in Italy’s letters. This provides statistical backing to some of Cowdrey’s arguments in his work on Gregory, namely that Gregory was attempting to enforce papal authority in the German-subject that was Bohemia, and assert the independence of Hungary from Germany, both of which were part of his larger strategy to contain Henry IV’s power in the east.

Another argument of Cowdrey is that Gregory was ‘flexible’, and that the idea he ‘acted upon a number of sharply defined and clearly formulated principles of papal action’ is misleading. Yet this does not necessarily show data-wise in the strategy of his letter writing. As can be seen, the amount of clerical and secular recipients generally changes fairly proportionately with one another, with only a slight change where secular overtakes as 1082 approaches. So while the content of letters may change, there does not seem to be any big shift in what part of society Gregory is writing to.

This work has suggested the possibilities of using modern data analysis to provide a fresh look at primary material that has already been extensively studied such as Gregory VII’s letters. There are many more possibilities, and it is our hope that someone will take this data set and do just that. One such idea could be breaking down the letters into zones of distance from Rome, and analysing whether this affects the content and tone of the letter. This could lead to a better picture of whether politics or earthly constraints were more of a determining factor in the writing of the letters.


H. E. J. Cowdrey, The Register of Pope Gregory VII 1073—1085: An English Translation (Oxford, 2002),

H. E. J. Cowdrey, Pope Gregory VII, 1073–1085 (Oxford, 1998)

Alexander Murray, ‘Pope Gregory VII and His Letters’, Traditio 22 (1966)

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Department of History