Isaiah seems to be referring to the coming of Nebuchadnezzar and the final destruction of Jerusalem in 587 BC. The Lord’s judgment over Jerusalem would be a day of confusion, trampling and tumult, a day which would bring destruction (“a battering down of walls”) and cries for help that would echo in the mountains (“a shouting to the mountains”).
5 For the Lord GOD of hosts has a day of tumult and trampling and confusion in the valley of vision, a battering down of walls and a shouting to the mountains.