The early modern iconographic representations of St. Clare of Assisi (1193–1253) often show her carrying the monstrance with the Eucharist. This act refers to the episode of September 1240, when the Saracen mercenaries of Emperor Federick II attacked the unprotected small monastery of the Poor Ladies of San Damiano. The weak and sick Clare is often portrayed as lifting up the monstrance while standing at the dormitory door and striking the Saracen troops below with the brilliance of the Eucharist. The target of this essay is to trace the evolution of this enigmatic scene in Italian art in connection with the Franciscan religious literature, particularly as expressed in sermons. The article will focus on the later phase of the popularity of this scene in early modern Italy. The story gains new meanings over the years; ultimately, St. Clare becomes a Crusade heroine defending Christianity against infidels and an emblem of Tridentine Catholic theology and its admiration for the Host.