(Rev. 19:21 KJV) 21 And the remnant were slain with the sword of him that sat upon the horse, which sword proceeded out of his mouth: and all the fowls were filled with their flesh.
It seems that the battle is over as soon as it starts and there is no question who wins.
There are two trains of thought as to who the remnant are.
The Beast was Taken
(Rev. 19:20 KJV) 20 And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.
That’s it. The battle is over as soon as it starts. As soon as Jesus steps foot upon the Mount of Olives the battle is over. The beast and the false prophet are immediately taken and cast into the Lake of Fire.