In 1573 Pope Pius V instituted the feast in
thanksgiving for the decisive victory of Christianity over Islamism.
The tradition of this advocation goes back to 1571, when the whole of Christendom was saved by Mary Help of Christians when Catholics throughout Europe prayed the Rosary. The great battle of Lepanto occurred on October 7th 1571. For this reason this date has been chosen as the feast of the Holy Rosary. In 1573 Pope Pius V instituted the feast in thanksgiving for the decisive victory of Christianity over Islamism.