Charles Ellicott Commentary Isaiah 14:31

"Howl, O gate; cry, O city; thou art melted away, O Philistia, all of thee; for there cometh a smoke out of the north, and there is no straggler in his ranks." — Isaiah 14:31 (ASV)

Howl, O gate ... —The gate, as elsewhere, is the symbol of the city’s strength. The city stands probably for Ashdod, as the most conspicuous of the Philistine cities.

From the north. —Here of the Assyrian invaders, as in Jeremiah 1:14; Jeremiah 10:22; Jeremiah 46:20 of the Chaldean. The smoke may be either that of the cities which the Assyrians burnt, or, more probably, the torch-signals, or beacons, which they used in their night marches or encampments (Jeremiah 6:1; Jeremiah 1:2). (See Note on Isaiah 4:5.)

None shall be alone in his appointed times. —Better, there is no straggler at the appointed places: i.e., all the troops shall meet at the rendezvous which was indicated by the column of fiery smoke as a signal.