Judges 7:16-20

And he divided the three hundred men into three units, and he put trumpets and empty pitchers into the hands of all of them, with torches inside the pitchers.

Then he said to them, “Look at me and do likewise. And behold, when I come to the outskirts of the camp, do as I do.

When I and all who are with me blow the trumpet, then you also blow the trumpets around the entire camp and say, ‘For the Lord and for Gideon!’ ” Confusion of the Enemy

So Gideon and the hundred men who were with him came to the outskirts of the camp at the beginning of the middle night watch, when they had just posted the watch; and they blew the trumpets and smashed the pitchers that were in their hands.

When the three units blew the trumpets and broke the pitchers, they held the torches in their left hands and the trumpets in their right hands for blowing, and shouted, “A sword for the Lord and for Gideon!”