For the people of that time, there was absolutely no doubt that the victory at Lepanto had been the direct result of the intercession of the Blessed Virgin and her rosary. Saint Pope Pius V was so convinced that Our Lady's intercession had brought victory. He wished that the victory should be liturgically celebrated in a grand manner throughout the catholic word every year.
In March of 1572, Pope Pius V instituted the annual feast of our Lady of Victory, directing that it be celebrated every year on October 7, remembering the Battle of Lepanto. He didn't' stop there, though. In a document titled Salvatoris Domini, he granted a plenary indulgence to all those who, in addition to the feast of Mary. This annual commemoration became known as "Rosary Sunday". Religious communities tended to refer to it as the Toties Quoties, which literally means "as often as", deriving from the number of plenary indulgences that could be gained on that day "as often as" a person fulfilled the conditions. However, the most common title used for the indulgence was to call it the "Great Pardon of the Rosary". For centuries, this indulgence was one of the most ample indulgences ever offered by the Church.
Initially, the Plenary indulgence for Rosary Sunday was only granted to members of the Confraternity of the Rosary, but it was later extended to all the faithful. The indulgence was praised and confirmed by many subsequent popes in official documents, including Pope Innocent XI in Nuper pro parte.
The condition for gaining the indulgence consisted of the following: A catholic had to visit a Dominican church with a rosary altar anytime from 2 p.m. on the Saturday preceding the feast until sundown on Rosary Sunday; pray for the intentions of the Holy Father during each visit; and go to confession and receive Holy Communion.
Thanks to Donald H. Calloway
