The Prayer to Saint Michael the Archangel usually refers to one specific Catholic prayer to Michael the Archangel, among the various prayers in existence that are addressed to him. It falls within the realm of prayers on spiritual warfare. From 1886 to 1964, this prayer was recited after Low Mass in the Catholic Church, although not incorporated into the text or the rubrics of the Mass. Other prayers to Saint Michael have also been officially approved and printed on prayer cards. Prayer to St. Michael the Archangel by Pope Leo XIII:

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, thrust into hell satan and all of the other evil spirits who prowl about the world seeking the ruin of souls. Amen

The threat to the church at the time was the Italian government's campaign against the Papal States.^[1] The 1890 text was composed and published twenty years after the capture of Rome had deprived the Pope of the last vestige of his temporal sovereignty. The papal residence at the Quirinal Palace had been converted into that of King Victor Emmanuel II of Italy.

In 1886, Pope Leo XIII added a Prayer to Saint Michael^[2] to the Leonine Prayers, which he had directed to be prayed after Low Mass two years earlier.^[3]

The English translation which was used in Ireland is quoted in James Joyce's novel Ulysses.^[6] Variant English translations include: "Holy Michael", "Saint Michael", "defend us in battle", "malice and snares", "may God rebuke him", "thrust into hell", "all evil spirits", "prowl about the world seeking the ruin", and "roam throughout the world seeking the ruin".^[7][8]

The prayer's opening words are similar to the Alleluia verse for Saint Michael’s feasts on 8 May and 29 September in the Roman Missal of the time, which ran:^[9]

A quite different prayer to Saint Michael was included in an exorcism formula published in the 1890−1891 edition of Acta Sanctae Sedis for use by bishops and by those priests authorized to perform exorcisms. To any of these who devoutly recited the formula daily Pope Leo XIII granted on 18 May 1890 a partial indulgence on each day and a plenary indulgence whenever they did so for a whole month.

This "Exorcism against Satan and the apostate angels" (Latin: Exorcismus in Satanam et angelos apostaticos) opens with some verses from the Psalms and then presents a long prayer to Saint Michael followed immediately by the actual prayer of exorcism, which began with a series of ten conjurations.^[14][15]

The exorcism formula, with its incorporated prayer to Saint Michael, was inserted into the 1898 edition of the Roman Ritual.^[16]

The Opus Sanctorum Angelorum presents the following prayer as an Act of Consecration to Saint Michael the Archangel:^[23]

Oh most noble Prince of the Angelic Hierarchies, valorous warrior of Almighty God and zealous lover of His glory, terror of the rebellious angels, and love and delight of all the just angels, my beloved Archangel Saint Michael, desiring to be numbered among your devoted servants, I, today offer and consecrate myself to you, and place myself, my family, and all I possess under your most powerful protection.

I entreat you not to look at how little, I, as your servant have to offer, being only a wretched sinner, but to gaze, rather, with favorable eye at the heartfelt affection with which this offering is made, and remember that if from this day onward I am under your patronage, you must during all my life assist me, and procure for me the pardon of my many grievous offenses, and sins, the grace to love with all my heart my God, my dear Savior Jesus, and my Sweet Mother Mary, and to obtain for me all the help necessary to arrive to my crown of glory.

Defend me always from my spiritual enemies, particularly in the last moments of my life.

Come then, oh Glorious Prince, and succor me in my last struggle, and with your powerful weapon cast far from me into the infernal abysses that prevaricator and proud angel that one day you prostrated in the celestial battle. Amen.

An article in the Roman journal Ephemerides Liturgicae^[24] in 1955 gave an account in Latin and Italian of how the Saint Michael prayer (in the Leonine Prayers) supposedly originated. Footnote nine of this account quotes an article in another Italian journal called La Settimana del Clero in 1947 by Domenico Pechenino, who worked at the Vatican during the time of Leo XIII, in which he said that after Leo had celebrated a Mass, he seemed to be staring at something, then went to his private office, with his attendants asking if he was well. Half an hour later he had written the Saint Michael prayer.

According to the same article in Ephemerides Liturgicae,^[25] Giovanni Nasalli Rocca Cardinal di Corneliano wrote in his Litteris Pastoralibus pro Quadragesima (Pastoral Letters for Lent) that according to Leo's private secretary, Rinaldo Angeli, Leo had seen a vision of demonic spirits who were congregating on the Eternal City (Rome); he wrote the Saint Michael prayer, and often said it, in response to the vision. Leo also personally wrote an exorcism prayer included in the Roman Ritual, and recommended that bishops and priests read these exorcisms often in their dioceses and parishes. This account, which speaks not of the prayer included in the Leonine Prayers but of the general exorcism of which the prayer was at first a part, and for which it later (1902) served as a sort of preface, an exorcism that the Pope recommended bishops and exorcist priests to perform often, indeed daily, in their dioceses and parishes, and that he himself recited often throughout the day.

Several variants of this story are told. The first to appear in print was in a 1933 German Sunday newspaper article, which stated that, as a result of the vision, shortly after 1880 Leo ordered the prayer to Saint Michael to be recited. In reality, it was only in 1884 that the Pope instituted the Leonine Prayers, still at that time without the prayer to Saint Michael.^[26] A year later, a German writer, Fr. Bers, tried to trace the origin of the story and declared that, though the story was widespread, nowhere could he find a trace of proof. Sources close to the institution of the prayer in 1886, including an account of a conversation with Leo XIII about his decision, say nothing of the alleged vision. Bers concluded that the story was a later invention that was spreading like a virus.^[27] The story is also found in Carl Vogl's 1935 Begone Satan: A Soul-Stirring Account of Diabolical Possession in Iowa.^[28]

In a later version, the vision is said to have occurred not in 1880, but on 13 October 1884, the year in which the Leonine Prayers were instituted but without the Prayer to Saint Michael. And yet another date, 25 September 1888, two years after Pope Leo XIII had added the prayer to the Leonine Prayers, was given in a 1991 version.^[29]

Another reported version of the vision relates a detailed conversation between the voice of Satan, who said he would destroy the Church if given enough power and time, and the voice of God, who permits Satan to do what he will.^[30] According to William Saunders, writing in the Arlington Catholic Herald, Leo said that God permitted Satan to choose a single century in which to work his worst against the Church; he chose the 20th century, and God privately revealed the then-future events of the 20th century to Leo.^[31]

• Novena to Saint Michael
• Saint Michael in the Catholic Church
• Vade retro satana