Accusations of holy-site pollution reliably mustered crusading zeal across decades.

Evidence

Other chroniclers recount more or less the same story; for Fulcher of Chartres this idolatrous worship of Mahomet had polluted the temple. Robert the Monk more graphically accuses the Saracens of having defiled the altars and baptismal fonts by smearing them with blood from circumcisions. This notion of “pollution” of the holy places of Jerusalem is a justification and a rallying cry: when Edessa falls to Zanqî, Bernard of Clairvaux and other preachers decry the pollution of the Holy Land by “heathen filth” [spurcitia paganorum] and call for purification through Christian swords. — John V. Tolan, Saracens, 662

Categorization

• ADDENDUM: Relevant to ‘On Sacrifice’ and to the broader ‘pollution + purification through violence’ frame; also connects to ‘Complaints About Immodesty’ in how disgust metaphors mobilize moral panics.
• QUESTION: Whether the ‘circumcision blood on fonts’ smear reflects an actual folk memory of Muslim practice or pure invention bears chasing in primary sources.