Charles Ellicott Commentary Zechariah 14:3

"Then shall Jehovah go forth, and fight against those nations, as when he fought in the day of battle." — Zechariah 14:3 (ASV)

Then shall the Lord go forth. — In the hour of Israel’s direst need the Lord will appear as their champion, as in former times. (Joshua 23:3; Judges 4:15; 1 Samuel 7:10; and especially 2 Chronicles 20:15.)