Today is the feast of Saint Michael (Michaelmas) and we do well to pray to this great angel and saint to protect and guard the Catholic Church from her enemies
According to legend, Pope Leo XIII (reigned from 1878-1903) composed the now famous "Prayer to Saint Michael" after celebrating the Holy Sacrifice of the Mass with a group of cardinals. During the Mass, the Holy Father fell to the floor at the foot of the altar. It seemed that the Holy Father had died or suffered from a stroke. Suddenly, the Pope revived and said, "What a horrible vision I was allowed to see."
Apparently the pontiff saw a future influx of demonic forces into the Catholic Church. He subsequently authored the following prayer to Saint Michael, seeking to gain further protection for the Church. Pope Leo XIII also ordered this prayer it be prayed by the priest and faithful at the end of every low Mass.
Sancte Michael Archangele, defende nos in proelio; contra nequitiam et insidias diaboli esto praesidium. Imperat illi Deus; supplices deprecamur: tuque, Princeps militiae coelestis, Satanam aliosque spiritus malignos, qui ad perditionem animarum pervagantur in mundo, divina virtute in infernum detrude. Amen.
Saint Michael the Archangel, defend us in the battle, be our safeguard and 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 evil spirits who wander through the world seeking the ruin of souls. Amen.
You can also read the "Long" Saint Michael Prayer composed by Pope Leo XIII here:
The "Long" Saint Michael Prayer.