Miracles that Stopped Medieval Soldiers
One of the most popular works in the Middle Ages was Dialogus miraculorum by a Cistercian monk named Caesarius of Heisterbach. Written in the first half of the thirteenth-century, it is a collection of 746 miracle stories. Caesarius’ tales cover many topics, from battling demons to seeing visions of saints.
A couple of these stories involve medieval soldiers who were stopped from carrying out their attacks by miraculous means:
In the time of the wars between Otto IV and Philip II, the country people went with their goods to the Oratory of St. Goar, which is, both from its situation, and the strength of its walls, a great stronghold. Warner de Boulaut, a rich and powerful man, came with battering-rams to storm the place. Those within, in great fear, set a crucifix in one of the windows against the besiegers, hoping that out of reverence to it they would cease from their work. One of the archers, in indignation, shot at the crucifix, and fixed an arrow in the arm, from which immediately blood began to flow. The aforesaid Warner, fearing on account of this miracle, made a vow to become a Crusader. Philip, Abbot of Ottiburgh, hearing of the wonder God had wrought, went to the place, and learnt the truth of it from the mouth of a Jew, who was present. He examined the wound, and the weapon which inflicted it.
In the times of the wars in Flanders, the Monastery of Cambron was besieged by soldiers, who, divided into several troops, sought to obtain an entrance. Some strove to set fire to the upper gate, heaping straw against it, and kindling it into a flame ; others tried to force the lower gate ; others with ladders ascended the walls. Now, there were within about fourteen soldiers and countrymen, who defended the place as well as they could. The Abbot, however, still trusted to escape by the help of heaven, and of a sudden the enemy began to take to flight, descending from the walls, and leaving the gates, from what reason it did not then appear. The general of the army afterwards declared, that when he had mounted the wall to encourage his men, he saw a great band of Monks in white, riding about the gardens on horseback, and driving off the soldiers.
You can read an English translation of Dialogus miraculorum in Cistercian legends of the thirteenth century, by Henry Collins, which is available on Archive.org. A manuscript of one of the copies of the work can be read from Utrecht University.