Michael, the archangel
Rev 12:7 And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
It was (or will be) spiritual warfare; good angels against bad angels. Michael, the head angel or the captain of the Lord's good angels fighting satan and his demonic angels. Michael is not Jesus as some of the false religions claim.
Jude 1:9 Yet Michael the archangel, when contending with the devil he disputed about the body of Moses, durst not bring against him a railing accusation, but said, The Lord rebuke thee.
Michael could not rebuke satan, being a created angel, but the Lord of Hosts could; God the Father and God the Son.
Mal 3:11 And I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast her fruit before the time in the field, saith the LORD of hosts.
Rev 12:8 And prevailed not; neither was their place found any more in heaven.
Rev 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.
The bad angels, or stars were cast out with him.
Mat 24:29 Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken:
When was satan cast out? In context this would occur in the middle of the last week of Daniel.
Dan 12:1 And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time thy people shall be delivered, every one that shall be found written in the book.
Jesus spoke of having seen satan cast out. He was in the serpent in the Garden of Eden, so it was some time before this.
Luke 10:17 And the seventy returned again with joy, saying, Lord, even the devils are subject unto us through thy name.
Luke 10:18 And he said unto them, I beheld Satan as lightning fall from heaven.
Satan still had access to heaven as an accuser of the brethren;
Job 1:12 And the LORD said unto Satan, Behold, all that he hath is in thy power; only upon himself put not forth thine hand. So Satan went forth from the presence of the LORD.
Michael cast him out permanently. Satan again would be cast into the bottomless pit for a thousand years, loosed and then the final casting into the lake of fire. (Rev 20)
Rev 12:10 And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.
Who spoke? it was a saint of God, a human in glory, one of the brethren? Or perhaps the voice of the martyrs calling out in one voice?
Rev 6:9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:
Rev 6:10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?
Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ.