Yesterday, October 7, was the feast of Our Lady of the Rosary. This is a short story I found about the origin of the feast of Our Lady of the Rosary.
On October 7, 1571, the combined Christian fleets under Don John of Austria achieved a significant naval victory over the Turks in the Straits of Lepanto. Thousands of Christians were liberated, the Turkish fleet was destroyed, and they suffered their first great defeat at sea.
In gratitude to God and to Our Lady, Pope St. Pius V ordered an annual commemoration to be made to Our Lady of Victory. In 1573, Pope Gregory XIII transferred the feast to the first Sunday of October with the title “Feast of the Most Holy Rosary” since the victory was won through invocation of Our Lady of the Rosary. In 1716, Pope Clement XII extended the feast to the whole Latin Rite calendar, assigning it to the first Sunday of October. Pope St. Pius X changed the date to October 7 in 1913. In 1969, Pope Paul VI changed the name of the feast to Our Lady of the Rosary.
The development of the Rosary had a long history. First, a practice developed of praying 150 Our Fathers in imitation of the 150 Psalms. Then there was a parallel practice of praying 150 Hail Marys. Soon a mystery of Jesus’ life was attached to each Hail Mary. Though Mary’s giving of the Rosary to St. Dominic is recognized as a legend, the development of this prayer form owes much to the followers of St. Dominic. One of them, Alan de la Roche, was known as the “apostle of the Rosary” and he founded the first Confraternity of the Rosary in the 15th century. In the 16th century, the Rosary was developed to its present form – with the 15 mysteries: Joyful, Sorrowful, and Glorious. In 2002, Pope John Paul II added the Luminous Mysteries.
I hope this helps in your devotion to our Blessed Mother as you pray the Rosary.