Judges 7:16-19

16And he divided the three hundred men into three companies, and he put a trumpet in every man’s hand, with empty pitchers, and lamps within the pitchers.12 17And he said unto them, Look on me, and do likewise: and, behold, when I come to the outside of the camp, it shall be that, as I do, so shall ye do. 18When I blow with a trumpet, I and all that are with me, then blow ye the trumpets also on every side of all the camp, and say, The sword of Yhwh, and of Gideon.

19So Gideon, and the hundred men that were with him, came unto the outside of the camp in the beginning of the middle watch; and they had but newly set the watch: and they blew the trumpets, and brake the pitchers that were in their hands.