Michael Ghislieri was born near Alessandria in Italy in 1504. He was a poor shepherd boy, who entered the Dominican Order at the age of 14 and was ordained a priest at the age of 24. After being ordained a bishop and named a Cardinal, he became pope at the age of 62, taking the name of Pope Pius V.
Perhaps the most famous success of his papacy was the miraculous victory of the Christian fleet in the battle of Lepanto on October 7, 1571. The island of Malta was attacked by the Turkish fleet, and nearly every man defending the fortress was killed in battle. The pope sent out a fleet to meet the enemy, requesting that each man on board pray the Rosary and receive communion.
Meanwhile, he called on all of Europe to recite the Rosary and ordered a 40 hour devotion in Rome during which time the battle took place. The Christian fleet, vastly outnumbered by the Turks, inflicted an impossible defeat on the Turkish navy, demolishing the entire fleet.
Decree by Pope Saint Pius V on the power of the Holy Rosary
... And so Dominic looked to that simple way of praying and beseeching God, accessible to all and wholly pious, which is called the Rosary, or Psalter of the Blessed Virgin Mary, in which the same most Blessed Virgin is venerated by the angelic greeting repeated one hundred and fifty times, that is, according to the number of the Davidic Psalter, and by the Lord’s Prayer with each decade. Interposed with these prayers are certain meditations showing forth the entire life of Our Lord Jesus Christ, thus completing the method of prayer devised by the Fathers of the Holy Roman Church.
This same method St. Dominic propagated, and it was, spread by the Friars of Blessed Dominic, ... Christ’s faithful, inflamed by these prayers, began immediately to be changed into new men.
The darkness of heresy began to be dispelled, and the light of the Catholic Faith to be revealed. Sodalities for this form of prayer began to be instituted in many places by the Friars of the same Order, ...
Following the example of our predecessors, seeing that the Church militant, which God has placed in our hands, in these our times is tossed this way and that by so many heresies, and is grievously troubled and afflicted by so many wars, and by the deprave morals of men, we also raise our eyes, weeping but full of hope, unto that same mountain, whence every aid comes forth, and we encourage and admonish each member of Christ’s faithful to do likewise in the Lord.
Given at Rome at St. Peter’s, 17 September 1569.