Full prayer of Pope Leo XIII to Saint Michael

O Glorious Archangel St. Michael, Prince of the heavenly host, be our defense in the terrible warfare which we carry on against principalities and powers, against the rulers of this world of darkness, the spirits of evil. Come to the aid of man, whom God created immortal, made in His own image and likeness, and redeemed at a great price from the tyranny of the devil. 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 their place for them any longer in Heaven. That cruel, that ancient serpent, who is called the devil or Satan who seduces the whole world, was cast into the abyss with his angels.

Behold, this primeval enemy and slayer of men 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 the 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 impiety, 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. In the holy Place itself, where has been set up the See of the most holy 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 give them victory. They venerate thee as their protector and patron; in thee holy Church glories as her defense against the malicious power 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 well 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 Most High, 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. Therefore having confided ourselves to thy protection and tutelage, we sacred ministers by our authority [if one is a layman, or a cleric who has not yet received the order of exorcist, say instead: by the authority of Holy Mother Church], trusting and secure in the Name of Jesus Christ Our God and Lord, we approach to repel the infestations of diabolical deceit.

V. Behold the Cross of the Lord; be scattered ye hostile powers.
R. The Lion of the tribe of Juda has conquered, the root of David.
V. Let Thy mercies be upon us, O Lord.
R. As we have hoped in Thee.
V. O Lord, hear my prayer.
R. And Let my cry come unto Thee.