The early Church Fathers recognized the importance of the angels and archangels, particularly St. Michael. Theodoret of Cyr (393-466) in his Interpretation of Daniel wrote, “We are taught that each one of us is entrusted to the care of an individual angel to guard and protect us, and to deliver us from the snares of evil demons. Archangels are entrusted with the tasks of guarding nations, as the Blessed Moses taught, and with those remarks the Blessed Daniel is in accord; for he himself speaks of ‘the chief of the Kingdom of the Persians,’ and a little later of the ‘chief of the Greeks,’ while he calls Michael the chief of Israel.'” The Church Fathers would also posit that St. Michael stood guard at the gate of paradise after Adam and Eve had been banished, and he was the angel through whom God published the Ten Commandments, who blocked the passage of Balaam (Number 22:20ff), and who destroyed the army of Sennacherib (2 Chronicles 32:21).
St. Basil and other Greek Fathers ranked St. Michael as the Prince of all the Angels. With the rise scholasticism and the exposition of the “nine choirs of angels,” some said St. Michael was the prince of the Seraphim, the first of the choirs. (However, St. Thomas Aquinas assigned St. Michael as the prince of the last choir, the angels.)
St. Michael the Archangel has been invoked for protection on various occasions. In 590, a great plague struck Rome. Pope St. Gregory the Great led a procession through the streets as an act of penance, seeking the forgiveness of and atoning for sin. At the tomb of Hadrian (now Castle Sant’ Angelo near St. Peter’s Basilica), St. Michael appeared and sheathed his sword, indicating the end of the plague. The Holy Father later built a chapel at the top of the tomb and to this day a large statue of St. Michael rests there. — from “The Prayer to St. Michael”