Judges 20:38-40

38The men of Israel had arranged with those waiting in ambush that they would make a big column of smoke rise from the city as a signal.

39Then the men of Israel would turn around in the battle. The men of Benjamin had already killed about 30 men of Israel. They even said, “Israel is completely defeated, just like in the first battle.”

40But when the column of smoke started to rise from the city, the men of Benjamin turned around and saw the whole city going up in smoke.