What does Isaiah 15:4 mean?

This passage has been describing the national grief in the nation of Moab over the apparent attacks and destruction of some of their major cities. The prophecy pictures all the men of the nation with their head and beard shaved. As well as everyone in the nation clothed with the rough sackcloth of mourning (Isaiah 15:1–3).

Now Isaiah adds that the cities of Heshbon and Elealeh cry out, as well. They have also been destroyed. These two cities are in territory that was originally given to the Israelite tribes of Gad and Reuben (Numbers 32:1–5). The Israelites and Moabites had disputed with each other for many years over that region. Moab's refusal to give it up may have been one reason for the Lord's judgment on them.

He goes on to say that the cries of those in Heshbon and Elealeh in the north can be heard as far south as Jahaz, several hours away. The shared grief of the people can be heard and felt throughout the land. Even the armed Moabite soldiers mourn together with the people. Soldiers are normally seen to be tough, but these men cry aloud along with everyone else. They tremble in their souls, so distraught that they could not defeat the sudden invasion by a powerful enemy.