While Saint Dominic was preaching the Rosary in Carcasone, a heretic made fun of the miracles and the fifteen mysteries of the Holy Rosary, and this prevented other heretics from being converted. As a punishment God suffered fifteen thousand devils to enter the man's body.
His parents took him to Father Dominic to be delivered from the evil spirits. He started to pray and begged everyone who was there to say the Rosary out loud with him, and at each Hail Mary Our Lady drove out one hundred devils out of the heretic's body and they came out in the form of red hot coals.
After he had been delivered he abjured his former errors, was converted and joined the Rosary Confraternity. Several of his associates did the same, having been greatly moved by his punishment and by the power of the Rosary.
The learned Franciscan, Carthagena, as well as several other authors, say that an extraordinary event took place in 1482: The Venerable James Sprenger and other religious of his order were zealously working to re-establish devotion to the Holy Rosary and also to erect a Confraternity in the city of Cologne.
Unfortunately two priests who were famous for their preaching ability were jealous of the great influence they were exerting through preaching the Rosary. So these two Fathers spoke against this devotion whenever they had a chance, and as they were very eloquent and had a great reputation they persuaded many people not to join the Confraternity.
One of them, bound and determined to achieve his wicked end, wrote a special sermon against the Rosary and planned to give it the following Sunday. But when it came time for the sermon he never appeared and, after a certain amount of waiting somebody went to fetch him. He was found dead, and evidently had died alone without any one to help him and without seeing a priest.
After convincing himself that death had been due to natural causes, the other priest decided to carry out his friend's plan and hoped to put an end to the Confraternity of the Rosary. However, when the day came for him to preach and it was time to give the sermon God punished him by striking him down with paralysis which deprived him both of the use of his limbs and of his power of speech.
At last he admitted his sin and likewise that of his friend and immediately, in his heart of hearts, he silently besought Our Lady to help him. He promised her that is she would only cure him he would preach the Holy Rosary with as much zeal as that with which he had formerly fought against it. For this end he implored her to restore his health and speech which she did, and finding himself instantaneously cured he rose up like another Saul, a persecutor turned defender of the Holy Rosary. He publicly acknowledged his former error and ever after preached the wonders of the Most Holy Rosary with great zeal and eloquence.
"The Rosary is the 'weapon' for these times." Padre Pio