This proposal focuses on a specific group of European missionaries in early modern times: the Jesuits of the 'Missio castrensis' to the army of Flanders. This was the Spanish Catholic army that criss-crossed Europe between Flanders and Italy during the Eighty Years' War and the Thirty Years' War (1568-1648). The comparative analysis of several unpublished sources makes it possible to follow the radical change in the attitude of these missionaries towards the men who were the object of their mission. While the war seems never to end, the correspondence of the missionaries, but also the mission journals, testify to a turnaround of the Jesuits, who modify their pastoral and human priorities. If at the beginning the discourses and practices referred to the context of the holy war against the heretics, with a clear separation between the attentions lavished on Catholics and a violent disinterest in the others, as the war continued, a new attention was addressed to all bodies suffering from the war as well as from the plague. The war changes everyone; also the Jesuits. The priority then becomes that of saving the bodies and their dignity (the burials), before taking care of the souls of those who wish to be taken care of. This was a profound upheaval, which in the mid-seventeenth century echoed the new attention to the poor, the sick and their needs.