The battle between the angels of God and the angels of the Devil is part of the portents envisioned by John the Evangelist in the Book of Revelations.
Biblical source: Rev 12:7-9.

East View: Orant.	South View: An angel spears a dragon.
North View: An angel spears a dragon.

DETAILS
Detail:

Related capitals:

Revelations Capitals:
Capital 10: Chaining the Devil, Og and Magog
Capital 11: Symbols of the Evangelists
Capital 15: Vision of John the Evangelist
Capital 51: Evangelists with Symbolic Beast's Heads
Capital 63: Grotesque Bowmen

Dragons and Beasts: 28, 29, 66, 69, 72

Revelations 12:7-9

⁷ Now war arose in heaven, Michael and his angels fighting against the dragon; and the dragon and his angels fought,
⁸ but they were defeated and there was no longer any place for them in heaven.
⁹ And the great dragon was thrown down, that ancient serpent, who is called the Devil and Satan, the deceiver of the whole world- he was thrown down to the earth, and his angels were thrown down with him.

The New Oxford Annotated Bible with the Apocrypha, Revised Standard Version.
Inscriptions based on Robert Favereau, Jean Michaud, and Bernadette Leplant, Corpus des Inscriptions de la France Medievale. Vol. 8, Ariege, Haute-Garonne, Hautes-Pyrenees, Tarn-et-Garonne. Paris: Centre National de la Recherche Scientifique, 1982.