Revelation

12:7 And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
12:8 And prevailed not; neither was their place found any more in heaven.
12:9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.

It is interesting to note that the dragon (the dragon is the Devil or Satan as stated in verse 9 above) took a third of the angels of heaven with him when he was cast out.

12:3 And there appeared another wonder in heaven; and behold a great red dragon, having seven heads and ten horns, and seven crowns upon his heads.
12:4 And his tail drew the third part of the stars of heaven, and did cast them to the earth:...