Isaiah 3:25-26. “Thy men shall fall by the sword, and thy mighty in the war. And her gates shall lament and mourn; and she being desolate shall sit upon the ground.”
The future is pretty bleak for Judah and Jerusalem. Strong men will be killed by the swords of the enemy; “the might” refers to the military, those trained as soldiers.
The gates were places where worshipers gathered for ceremony and celebration; the city would be desolate, or ruined; the people would cry, weep, mourn, and sit upon the ground, a picture of utter humiliation.
I need to clarify here, because I think I missed it earlier. In verse 18, the phrase “In that day” tells us that the following prophecies concern not just the present times, but more specifically the far future when AntiChrist will destroy Jerusalem and humiliate the people. Refer to Zech. 14:1-5, 14; and Rev. 19:11-21.