For it is a day of trouble, and of treading down, and of perplexity by the Lord GOD of hosts in the valley of vision, breaking down the walls, and of crying to the mountains. For (it is) a day of trouble ... by the Lord God of hosts - literally, 'for lª- the Lord' - i:e., sent by or from the Lord. So the Hebrew particle is used as for, directed on the part of, in Isaiah 19:15.
And of treading down - of Jerusalem by the Gentiles (Luke 21:22-24).
In the valley of vision - (note, Isaiah 22:1) Some think a valley near Ophel is meant as about to be the scene of devastation (cf. Isaiah 32:13-14, note).
Breaking down the walls - i:e., 'a day of breaking the walls' of the city.
And of crying to the mountains - the mournful cry of the townsmen reaches to (Maurer translates toward) the mountains, and is echoed back by them. Josephus describes in the very same language the scene at the assault of Jerusalem under Titus. To this the prophecy probably refers ultimately. If, as some think, the 'cry' is that of those escaping to the mountains, cf. Mark 13:14; Matthew 24:16, with this.