The war of angels was caused by Lucifer after he became outcasted by God. He brought for instance on third of all angels up against God and the fight between light and darkness began.
Gods fighters carried off, last but not least with the help of archangel Michael, which defeated its own brother Lucifer in this fight: On its sign there were written the words ' who is like God?'.
Michaels name meant after the Hebrew one ' who is like God?' and with these words he defeated Lucifer, which wanted to be like God, and its appendix.
The bible tells the following about this fight
Revelation 12: And a great portent appeared in heaven, a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars; 2 she was with child and she cried out in her pangs of birth, in anguish for delivery. 3 And another portent appeared in heaven; behold, a great red dragon, with seven heads and ten horns, and seven diadems upon his heads. 4 His tail swept down a third of the stars of heaven, and cast them to the earth. And the dragon stood before the woman who was about to bear a child, that he might devour her child when she brought it forth; 5 she brought forth a male child, one who is to rule all the nations with a rod of iron, but her child was caught up to God and to his throne, 6 and the woman fled into the wilderness, where she has a place prepared by God, in which to be nourished for one thousand two hundred and sixty days. 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. 10 And I heard a loud voice in heaven, saying, 'Now the salvation and the power and the kingdom of our God and the authority of his Christ have come, for the accuser of our brethren has been thrown down, who accuses them day and night before our God. 11 And they have conquered him by the blood of the Lamb and by the word of their testimony, for they loved not their lives even unto death. 12 Rejoice then, O heaven and you that dwell therein! But woe to you, O earth and sea, for the devil has come down to you in great wrath, because he knows that his time is short!' 13 And when the dragon saw that he had been thrown down to the earth, he pursued the woman who had borne the male child. 14 But the woman was given the two wings of the great eagle that she might fly from the serpent into the wilderness, to the place where she is to be nourished for a time, and times, and half a time. 15 The serpent poured water like a river out of his mouth after the woman, to sweep her away with the flood. 16 But the earth came to the help of the woman, and the earth opened its mouth and swallowed the river which the dragon had poured from his mouth. 17 Then the dragon was angry with the woman, and went off to make war on the rest of her offspring, on those who keep the commandments of God and bear testimony to Jesus. And he stood on the sand of the sea.