The feast was introduced by Pope St. Pius V (1504-1572) in the year 1571 to commemorate the miraculous victory of the Christian forces in the Battle of Lepanto on October 7, 1571. The pope attributed more to the "arms" of the Rosary than the power of cannons and the valor of the soldiers who fought there.
Queen of Peace, pray for us.
Pax,
Father Mike