v. 21 — Internal collapse in the invading force
YHWH “calls for a ” against the invader “to all my mountains,” resulting in intramural violence: each man’s sword turns against his brother.
v. 22 — Layered disasters on leader, troops, and allies
The invader is confronted with pestilence and bloodshed, followed by a sweeping description of catastrophic weather and destructive forces directed at the leader, his hordes, and accompanying peoples.
v. 23 — Public outcome among the nations
The stated purpose is YHWH’s self-display on an international stage, becoming publicly in the eyes of many nations.