The Rosary is more powerful than any weapon

“There is none among you, venerable brethren, who will not remember how great trouble and grief God's Holy Church suffered from the Albigensian heretics, who sprung from the sect of the later Manicheans, and who filled the South of France and other portions of the Latin world with their pernicious errors, and carrying everywhere the terror of their arms, strove far and wide to rule by massacre and ruin. Our merciful God, as you know, raised up against these most dire enemies a most holy man, the illustrious parent and founder of the Dominican Order.

Great in the integrity of his doctrine, in his example of virtue, and by his apostolic labors, he proceeded undauntedly to attack the enemies of the Catholic Church, not by force of arms; but trusting wholly to that devotion which he was the first to institute under the name of the Holy Rosary, which was disseminated through the length and breadth of the earth by him and his pupils. Guided, in fact, by divine inspiration and grace, he foresaw that this devotion, like a most powerful warlike weapon, would be the means of putting the enemy to flight, and of confounding their audacity and mad impiety. Such was indeed its result. Thanks to this new method of prayer - when adopted and properly carried out as instituted by the Holy Father St. Dominic - piety, faith, and union began to return, and the projects and devices of the heretics to fall to pieces. Many wanderers also returned to the way of salvation, and the wrath of the impious was restrained by the arms of those Catholics who had determined to repel their violence.”

Pope Leo XIII (1810-1903), Encyclical Supremi Apostolatus Officio, on devotion of the Rosary - September 1, 1883