Original Version of the Prayer to St. Michael by Pope Leo XIII (1886)

Sanctus Míchael Archángelus
Prínceps gloriosíssime caeléstis milítiae, sancte Míchael
Archángele, defénde nos in proelio advérsus príncipes et
potestátes, advérsus mundi rectóres tenebrárum harum,
contra spirituália nequítiae in caeléstibus.
Veni in auxílium hóminum, quos Deus ad imáginem
similitúdinis suae fecit, et a tyránnide diáboli emit prétio
magno.
Te custódem et patrónum sancta venerátur Ecclésia; tibi
trádidit Dóminus ánimas redemptórum in supérna
felicitáte locándas.
Deprecáre Deum pacis, ut cónterat Sátanam sub pédibus
nostris, ne ultra váleat captívos tenére hómines et Ecclésiae
nocére.
Offer nostras preces in conspéctu Altíssimi, ut cito
antícipent nos misericórdiae Dómini, et apprehéndas
dracónem, serpéntem antíquum, qui est diábolus et
sátanas et ligátum mittas in abýssum, ut non sedúcat
ámplius gentes.
Amen.


For those who can't speak Latin:

Glorious Prince of the Celestial Host, St. Michael
the Archangel, defend us in the conflict which we
have to sustain against principalities and powers,
against the rulers of the world of darkness, against
the spirits of wickedness in the high places (Eph
6:12). Come to the rescue of men whom God has
redeemed at a great price from the tyranny of the
devil. It is thou whom Holy Church venerates as her
guardian and her protector; thou whom the Lord
has charged to conduct redeemed souls into heaven.
Pray therefore, the God of peace, to subdue Satan
beneath our feet, that he may no longer retain men
captive nor do injury to the Church. Present our
prayers to the Most High, that without delay they
may draw His mercy down upon us. Seize "the
dragon, the ancient serpent, which is the devil and
Satan," bind him and cast him into the bottomless
pit..."that he may no longer seduce the nations"
(Rev 20:2-3).

Photos
Top: St. Michael in the Basilica of Our Lady of Mercy, Barcelona.
Bottom: St. Michael in the Cathedral of Brussels.