In1209,SimondeMontfortledacrusadeagainsttheCatharsinsouthernFranceandtookthetownofBeziers.Whenthetownwassacked,aquestionaroseoverhowitsupstandingChristiansmightbedistinguishedfromthedamnedheretics.Monfort'ssolutionwassimple:"Killthemall.TheLordwillknowhisown."..Tensofthousandsofmen,women,andchildrenwereconsequentlykilled.
一二○九年,一支十字軍由孟福爾率領,進犯法國南部卡特里派教徒,攻下了貝濟耶城,準備洗劫,問題是難以分辨城中持守正道的基督教徒和罪該萬死的異端教徒。孟福爾有個很簡單的辦法:「格殺勿論。天主之徒,天主自會分辨。」數以萬計成年男女以至兒童於是被殺。