Michaelmas (/ˈmɪkəlməs/; also known as the Feast of Saints Michael, Gabriel, and Raphael, the Feast of the Archangels, or the Feast of Saint Michael and All Angels) is a minor Christian festival observed in some Western liturgical calendars on 29 September. In some denominations a reference to a fourth angel, usually Uriel, is also added. Michaelmas has been one of the four quarter days of the financial year. The Serbian Orthodox Church observes the feast, whereas most Eastern Orthodox Churches do not. The Greek and Romanian Orthodox honor the archangels on 8 November instead, observed by the Cherubim and Seraphim also.
In Christian angelology, the Archangel Michael is the greatest of all the Archangels and is honored for defeating Satan in the war in heaven. He is one of the principal angelic warriors, seen as a protector against the dark of night, and the administrator of cosmic intelligence. Michaelmas has also delineated time and seasons for secular purposes, as well, particularly in Britain and Ireland as one of the quarter days.