Charlemagne had placed his glory and his salvation under the protection of Our Lady. In 778, after his famous campaign of Spain, he carried out the “cleansing” of the last Saracen pockets in the south of France. However, there was a Saracen prince named Mirat who resisted his assaults. To all the summons to surrender, this Muslim prince proudly answered: "I would prefer death to the shame of capitulation."
Discouraged, Charlemagne was about to raise the siege when his chaplain, the bishop of Le Puy, was allowed up to the citadel as a parliamentarian. Once before Mirat, he said to him: "Since you do not wish to go to Charlemagne, the greatest of princes, at least recognize as your suzerain the noblest Lady ever, Holy Mary of Le Puy, Mother of God. I am her servant, be her knight."
Without hesitating, Mirat declared that he was ready to surrender his arms to the servant of Our Lady and to receive baptism, on condition that his county would never obey, in his own time or in his descendants’, anyone else than Her. Charlemagne confirmed the agreement.
Mirat received baptism from the bishop of Le Puy and took the name of Lorda (“rose” in Arabic), which was transformed into "Lourdes."
Marquis de La Franquerie
In La Vierge Marie dans l’histoire de France (The Virgin Mary in the History of France) – Resiac.