Prayer to Saint Michael the Archangel

The Prayer:

Sancte Michael Archangele, defende nos in proelio. contra nequitiam et insidias diaboli esto praesidium. Imperet illi Deus, supplices deprecamur: tuque, Princeps militiae caelestis, Satanam aliosque spiritus malignos, qui ad perditionem animarum pervagantur in mundo, divina virtute, in infernum detrude. Amen.

Saint Michael the Archangel, defend us in battle;be our protection against the wickedness and snares of the devil. May God rebuke him, we humbly pray: and do thou, O Prince of the heavenly host, by the power of God, cast into hell Satan and all evil spirits who wander through the world seeking the ruin of souls. Amen.

History:

An article in the Ephemerides Liturgicae (V. LXIX, pages 54-60) in 1955 gave an account of how this prayer came to be. Fr. Domenico Pechenino who worked at the Vatican during the time of Leo XIII, stated:

I do not remember the exact year (note: the earliest form of the prayer dates to 1880). One morning the
great Pope Leo XIII had celebrated a Mass and, as usual, was attending a Mass of thanksgiving. Suddenly, we saw him raise his head and stare at something above the celebrant's head. He was staring motionlessly, without batting an eye. His expression was one of horror and awe; the color and look on his face changing rapidly.

Something unusual and grave was happening in him. Finally, as though coming to his senses, he lightly but firmly tapped his hand and rose to his feet. He headed for his private office. His retinue
followed anxiously and solicitously, whispering: 'Holy Father, are you not feeling well? Do you need anything?' He answered: 'Nothing, nothing.' About half an hour later, he called for the Secretary of the Congregation of Rites and, handing him a sheet of paper, requested that it be printed and sent to all the
ordinaries around the world. What was that paper? It was the prayer that we recite with the people at the end of every Mass. It is the plea to Mary and the passionate request to the Prince of the heavenly host, [St. Michael: Saint Michael the Archangel, defend us in battle] beseeching God to send Satan back to hell.

According to the same article, Cardinal Giovanni Nasalli Rocca di Corneliano wrote in his Litteris Pastoralibus pro Quadragesima (Pastoral Letters for Lent) that

"the sentence 'The evil spirits who wander through the world for the ruin of souls' has a historical explanation that was many times repeated by his private secretary, Monsignor Rinaldo Angeli. Leo XIII
truly saw, in a vision, demonic spirits who were congregating on the Eternal City (Rome). The prayer that he asked all the Church to recite was the fruit of that experience. He would recite that prayer with strong, powerful voice: we heard it many a time in the Vatican Basilica. Leo XIII also personally wrote an exorcism that is included in the Roman Ritual. He recommended that bishops and priests read these exorcisms often in their dioceses and parishes. He himself would recite them often throughout the day."

The prayer is one of the Leonine Prayers Pope Leo XIII added to the end of the Low Mass. The prayers were, 3 Ave Marias, a Salve Regina, versicle, response, prayers for the conversion of sinners, prayers for the welfare of the Church, and the Saint Michael Prayer.

These prayers were suppressed from use in the Liturgy in the wake of the liturgical reforms of 1965. Although they have been suppressed from liturgical function, we are all encouraged to pray it in defense of the evil one. Prayer is the first line of defense against Satan.