Judges 20:36-38

36So the Benjamites realized that they were defeated. Then men of Israel gave ground to the Benjamites, because they relied on the men in ambush whom they had placed against Gibeah.

37Then the men in ambush quickly rushed and attacked Gibeah; and the men in ambush also deployed and struck the entire city with the edge of the sword.

38Now the appointed signal between the men of Israel and the men in ambush was that they would make a great cloud of smoke rise from the city.