Albert Barnes Commentary Judges 3:28

"And he said unto them, Follow after me; for Jehovah hath delivered your enemies the Moabites into your hand. And they went down after him, and took the fords of the Jordan against the Moabites, and suffered not a man to pass over." — Judges 3:28 (ASV)

Ehud “went down” from the mountain of Ephraim into the Jordan valley beneath it, straight to the Jordan fords (Joshua 2:7), so as to intercept all communication between the Moabites on the west side and their countrymen on the east.