Network dynamics of a Holy War: the Fourth Crusade

The Fourth Crusade, initiated by Pope Innocent III for the purpose of the conquest of Egypt and the “liberation” of the Holy Land, ended in 1204 in the capture and looting of Constantinople, capital of the Christian Roman Empire of the East (commonly called the Byzantine one). The most important chronicler of the crusade, Geoffrey of Villehardouin (ca. 1160-1213), vividly describes the process of diffusion of the call to arms and the mobilisation for the “Holy War” among the highest nobility of northern France (see text below). It was Pope Innocent III himself who set the ball rolling by making use of a charismatic preacher (Fulk of Neuilly); but then the recruitment took place especially via the networks of allegiance and kinship among the aristocracy.

Tools of network analysis and GIS enable us to map this mobilisation process both in its social and spatial dimension; such an approach also allows for comparisons with modern-day diffusion of such ideas and the recruitment of individuals for violence in the name of religion.

Network of Holy War 4th Crusade JPK OEAW 2016.wmv (3583921)

Text: Johannes Preiser-Kapeller, OEAW (email:


Geoffrey of Villehardouin, The Conquest of Constantinople, cap. 1-8 (transl. Smith 2008):

Be it known to you that eleven hundred and ninety-seven years after the Incarnation of our Lord Jesus Christ, in the time of Innocent Pope of Rome, and Philip King of France, and Richard King of England, there was in France a holy man named Fulk of Neuilly - which Neuilly is between Lagni-sur-Marne and Paris - and he was a priest and held the cure of the village. And this said Fulk began to speak of God throughout the Isle-de-France, and the other countries round about; and you must know that by him the Lord wrought many miracles.  Be it known to you further, that the fame of this holy man so spread, that it reached the Pope of Rome, Innocent; and the Pope sent to France, and ordered the right worthy man to preach the cross (the Crusade) by his authority. And afterwards the Pope sent a cardinal of his, Master Peter of Capua, who himself had taken the cross, to proclaim the Indulgence of which I now tell you, viz., that all who should take the cross and serve in the host for one year, would be delivered from all the sins they had committed, and acknowledged in confession. And because this indulgence was so great, the hearts of men were much moved, and many took the cross for the greatness of the pardon.

The other year after that right worthy man Fulk had so spoken of God, there was held a tourney in Champagne, at a castle called Ecri, and by God's grace it so happened that Thibaut, Count of Champagne and Brie, took the cross, and the Count Louis of Blois and Chartres likewise; and this was at the beginning of Advent (28th November 1199). Now you must know that this Count Thibaut was but a young man, and not more than twenty-two years of age, and the Count Louis not more than twenty-seven. These two counts were nephews and cousins-german to the King of France, and, on the other part, nephews to the King of England. (…) In the land of Count Thibaut of Champagne took the cross Garnier, Bishop of Troyes, Count Walter of Brienne, Geoffry of Joinville*, who was seneschal of the land, Robert his brother, Walter of Vignory, Walter of Montbéliard, Eustace of Conflans, Guy of Plessis his brother, Henry of Arzilliéres, Oger of Saint-Chéron, Villain of Neuilly, Geoffry of Villhardouin, Marshal of Champagne, Geoffry his nephew, William of Nully, Walter of Fuligny, Everard of Montigny, Manasses of l'Isle, Macaire of Sainte-Menehould, Miles the Brabant, Guy of Chappes, Clerembaud his nephew, Renaud of Dampierre, John Foisnous, and many other right worthy men whom this book does not here mention by name. With Count Louis took the cross Gervais of Châtel Hervée his son John of Virsin, Oliver of Rochefort, Henry of Montreuil, Payen of Orléans, Peter of Bracietix, Hugh his brother, William of Sains, John of Frialze, Walter of Gaudonville, Hugh of Cormeray, Geoffry his brother, Hervée of Beauvoir, Robert of Frouville, Peter his brother, Orri of l'Isle, Robert of Quartier, and many more whom this book does not here mention by name. (…)

At the beginning of the following Lent, on the day when folk are marked with ashes (23rd February 1200), the cross was taken at Bruges by Count Baldwin of Flanders and Hainault, and by the Countess Mary his wife, who was sister to the Count Thibaut of Champagne. Afterwards took the cross, Henry his brother, Thierri his nephew, who was the son of Count Philip of Flanders, William the advocate of Béthune, Conon his brother, John of Nêsle Castellan of Bruges, Renier of Trit, Reginald his son, Matthew of Wallincourt, James of Avesnes, Baldwin of Beauvoir, Hugh of Beaumetz, Gérard of Mancicourt, Odo of Ham, William of Gommegnies, Dreux of Beaurain, Roger of Marck, Eustace of Saubruic, Francis of Colemi, Walter of Bousies, Reginald of Mons, Walter of Tombes, Bernard of Somergen, and many more right worthy men in great number, with regard to whom this book does not speak further.”