And there was war in heaven:
Michael and his angels fought against the dragon;
and the dragon fought and his angels, and prevailed not;
neither was their place found any more in heaven.
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.
Rev. 12:7-9
"Michael is the archangel (Jude 9), that is, the chief or prince of the 
angels;
---and the archangel is Christ, for it is the voice of the archangel that will be heard at the last great day, when the dead shall be raised (1 Thess. 4:16); and Christ declared (John 5:26-29) that his own voice would be the one that should penetrate the graves, and call forth the dead.
Therefore this war in heaven was between Christ and his angels on one side, and Satan and his angels on the other side.
It was the beginning of the great controversy,
which has been going on till the present time.
When Christ was on earth he again met the devil in person, and again vanquished him;....Satan still opposes Christ by seeking to blind the minds of men so that the light of the glorious gospel of Christ may not shine unto them (2 Cor. 4:3, 4); and the contest will cease only with the utter destruction of Satan and all his works."
E.J. Waggoner