This contribution successively approaches the word ‘crusade’ from a double perspective: firstly, it is a question of apprehending the very uses of the word within the leagues of virtue which multiplied at the beginning of the Third Republic, in a context where many organizations are joining forces to fight against what they call the social hazard of public immorality. To what extent do they use the word crusade, or on the contrary do they avoid it to designate their fight? In a second perspective, it is a question of examining the methods of the sociological qualification of these movements in terms of “moral crusades”, resulting from an Anglo-Saxon tradition of the sociology of collective mobilizations.