Despite being just over one hundred years old, the Prayer to Saint Michael is a prayer almost as familiar as the Our Father, Hail Mary, or Glory Be. It's history is interesting.
It is said that Pope Leo XIII had a vision at Holy Mass that terrified him. The tradition varies at this point. Either he saw devils congregating around the Holy See or he heard that it was granted to Satan to try to undermine the Church for the next one hundred years. Whichever it was (maybe both!), Pope Leo XIII composed this prayer and ordered in 1886 that it be recited after every Low Mass. This custom was suppressed in 1964.
The text of the prayer is as follows:
Sancte Michael Archangele,And this is the commonly received English translation of the prayer:
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.