Albert Barnes Commentary Jeremiah 49:5

"Behold, I will bring a fear upon thee, saith the Lord, Jehovah of hosts, from all that are round about thee; and ye shall be driven out every man right forth, and there shall be none to gather together the fugitives." — Jeremiah 49:5 (ASV)

Every man right forth - The Ammonites will live in terror of the tribes which rove in the neighborhood, and at the slightest alarm will flee straight away without resistance.