The Enemy Within: Crusading against Christians
SOME of the most important crusades in the late Middle Ages were waged against men and women who had been baptized as Catholics. In some cases they comprised groups holding heterodox beliefs, against whom the normal procedures established by the Church for the investigation and suppression of heresy had failed, or could not even be applied. In others they were individuals in possession of secular authority, whose political opposition to the papacy was construed as posing a serious threat to the integrity and faith of the Church. Both forms of crusade, and especially the latter, aroused controversy in their day; and they still provoke lively disagreement amongst scholars of the crusading movement. In this chapter we shall therefore need not only to examine the crusades themselves, but also to give some attention to their historical origins and the polemic to which they gave rise.
In the 1320s the publicist Augustinus Triumphus, posing the question 'Should the Pope send crusaders against tyrants who resist him?', played Devil's Advocate with the reply 'Since they are Christians, tyrants are signed with the cross. Consequently they must not be overthrown by people signed with the cross (crucesignati).' Christ's soldiers should not fight against those who had been received into His Church. Augustinus's answer to this criticism was essentially the same as that put forward about seventy years previously by the great canonist Hostiensis, who had written:
If it seems correct that we should promote the crusade overseas (crux transmarina), which is preached in order to acquire or recover the Holy Land, then we should use all the more vigour in preaching the crusade on this side of the sea (crux cismarina), against schismatics, which is aimed at the preservation of ecclesiastical