Pope Leo XIII wrote a prayer to Saint Michael after a vision in 1884

In 1884, at the close of Mass, Pope Leo XIII froze for several moments, his gaze fixed on something. Emerging from this unusual state, the pontiff hastily left the church. Half an hour later he summoned the secretary of the congregation and handed him a freshly written text of a prayer to Saint Michael, which was to be sent to all the bishops. The prayer was officially recited at the end of every service. The Pope explained that he had had a vision of otherworldly forces present in Rome.

The text of the prayer addresses the Archangel Michael, asking him to defend us in the struggle against evil, which prowls the world for the ruin of souls.

Pope Leo XIII described his vision as an exchange of voices between God and the dark powers, after which terrible scenes of hell were revealed to him, and at the end the holy Archangel Michael intervened, appearing in answer to the prayers addressed to him. Leo XIII campaigned for the spread of his prayer to Saint Michael and for its recitation at the end of every Mass, wishing to impress upon the faithful the need to pray fervently for the conversion of souls and for the victory of the Lord's army over the forces of evil, so active in the world.