He is viewed as the field commander of the Army of God. he leads God's armies against Satan's forces during his uprising.
In the book of Daniel, Michael appears as "one of the chief princes." who in Daniel's vision comes to Gabriel's aid in his contest with the angel of Persia (Dobiel). Michael is also described there as the advocate of the Children of Israel and as a 
"great prince who stands up for the children of your [Daniel's] people". In Hebrew, Michael means "who is like God" (mi-who, ke-as or like, El-deity), 
which in Talmudic tradition is interpreted as a rhetorical question: "Who is like God?" (which expects an answer in the negative) to imply that no one is like God. In this way, Michael is reinterpreted as a symbol of humility before God.
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Saint Michael is my Angel...