Pope Leo XIII personally started the practice of devoting October to the Rosary devotion. In a letter of September 1, 1883, mindful of the Rosary's power to strengthen faith and foster a life of virtue, he outlined the triumphs of the Rosary in past times and admonished the faithful to dedicate the month of October to the blessed Virgin through the daily recitation of her Rosary in the presence of the Blessed Sacrament, in order to obtain through her intercession the grace that God would console and defend His Church in her sufferings.
Queen of the most holy Rosary, pray for us.
Indulgence of 300 days.
Source: The Prayer Book, Catholic Press