Pope Leo XIII is known for his devotion to St. Michael. He is the one who first asked the Prayer to St. Michael to be added to the Prayers after the Mass and later, he also composed and promulgated an Exorcism against the devil which includes a special Prayer to St. Michael.
The "Leonine Prayers" originated in 1884, when Pope Leo XIII ordered certain prayers (three Hail Marys, the Hail Holy Queen, and the prayer for the Church) to be said after Low Mass, in defense of the independence of the Holy See. God's help was sought for a satisfactory solution to the loss of the Pope's temporal sovereignty, which deprived him of the independence felt to be required for effective use of his spiritual authority1.
Prayer to Saint Michael
In 1886, after celebrating his mass, the Pope had a horrific vision of demonic spirits congregating in Rome. This vision had a great impression on Leo XIII and prompted him to write, promulgate the Saint Michael prayer. He ordered the Prayer to Saint Michael be added to the Leonine Prayers. The prayer's opening words are similar to the Alleluia verse for Saint Michael’s feasts on 29 September in the Roman Missal.
In 1890, twenty years after the capture of Rome that had deprived the Papacy of the last vestige of its temporal sovereignty, Pope Leo XIII wrote an exorcism prayer and recommended that bishops and priests read these exorcisms often in their dioceses and parishes.
The Pope inserted this prayer into the edition of the Roman Ritual. This "Exorcism against Satan and the Apostate Angels" 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.2
In 1902, a year and a half before the death of Pope Leo XIII, a new edition of the Roman Ritual considerably shortened the exorcism formula as a whole and in particular the prayer to Saint Michael within it. The revision of the text reflects improved relations between the Holy See and the Kingdom of Italy.
The Pope's status as a temporal leader was restored in 1929 by the creation of the State of Vatican City, and in the following year, Pope Pius XI ordered that the intention for which the Leonine Prayers should from then on be offered was "to permit tranquility and freedom to profess the faith to be restored to the afflicted people of Russia".3
Paul VI & Leonine Prayers
Paul VI suppressed the obligation to pray the Leonine prayers by the 26 September 1964 Instruction Inter oecumenici. However, after the promulgation of the Novus Ordo Missae, the priests who were faithful to the Latin Mass never stopped to pray these Leonine Prayers.
Exorcism of Leo XIII against Satan and the Apostate Angels
O glorious Archangel St. Michael, Prince of the heavenly host, defend us in battle, and in the struggle which is ours against the principalities and powers, against the rulers of this world of darkness, against spirits of evil in high places (Eph 6:12).
Come to the aid of men, whom God created immortal, made in His own image and likeness, and redeemed at a great price from the tyranny of the devil (Wisdom 2:23–24, 1 Cor 6:20).
Fight this day the battle of the Lord, together with the holy angels, as already thou hast fought the leader of the proud angels, Lucifer, and his apostate host, who were powerless to resist thee, nor was there a place for them any longer in Heaven. But that cruel, that ancient serpent, who is called the devil or Satan, who seduces the whole world, was cast into the abyss with all his angels (Rev 12:7–9).
Behold, this primeval enemy and slayer of man has taken courage, transformed into an angel of light, he wanders about with all the multitude of wicked spirits, invading the earth in order to blot out the name of God and of his Christ, to seize upon, slay and cast into eternal perdition souls destined for the crown of eternal glory.
This wicked dragon pours out, as a most impure flood, the venom of his malice on men of depraved mind and corrupt heart, the spirit of lying, of impiety, of blasphemy, and the pestilent breath of impurity, and of every vice and iniquity.
These most crafty enemies have filled and inebriated with gall and bitterness the Church, the spouse of the Immaculate Lamb, and have laid impious hands on her most sacred possessions (Lam 3:15).
In the Holy Place itself, where has been set up the See of the most blessed Peter and the Chair of Truth for the light of the world, they have raised the throne of their abominable impiety, with the iniquitous design that when the Pastor has been struck, the sheep may be scattered.
Arise then, O invincible Prince, bring help against the attacks of the lost spirits to the people of God, and bring them the victory.
The Church venerates thee as protector and patron; in thee holy Church glories as her defense against the malicious powers of this world and of hell; to thee has God entrusted the souls of men to be established in heavenly beatitude.
Oh, pray to the God of peace that He may put Satan under our feet, so far conquered that he may no longer be able to hold men in captivity and harm the Church.
Offer our prayers in the sight of the Highest, so that they may quickly conciliate the mercies of the Lord; and beating down the dragon, the ancient serpent, who is the devil and Satan, do thou again make him captive in the abyss, that he may no longer seduce the nations. Amen.