Judges 20:38-40

38Now the appointed signal between the men of Israel and the men in the main ambush was that when they made a great cloud of smoke rise up out of the city

39the men of Israel should turn in battle. Now Benjamin had begun to strike and kill about thirty men of Israel. They said, "Surely they are defeated before us, as in the first battle."

40But when the signal began to rise out of the city in a column of smoke, the Benjaminites looked behind them, and behold, the whole of the city went up in smoke to heaven.