Queen Blanche of Castille, deeply sorrowful over twelve years of childlessness, turned to St. Dominic for guidance. He counseled her to pray the Rosary daily, asking God through the Blessed Virgin for the gift of motherhood. Trusting in this devotion, she faithfully followed his advice and soon gave birth to a son, Philip, who tragically died in infancy. Undeterred, the Queen renewed her plea to Our Lady, distributing rosaries across the kingdom and urging others to join her in prayer. Her faith was richly rewarded when, in 1215, she gave birth to St. Louis—who would become one of France’s greatest and holiest kings, a lasting testament to the power of the Rosary and the fruit of persistent prayer.
Source: https://wayoftherose.org