Judges 7:16-20

ISV(i) 16 Then he separated the 300 men into three companies, gave them each trumpets to carry, along with jars into which he placed lit torches.
17 He instructed them, “Watch me, and do what I do. When we come to the outer perimeter of the encampment, do what I do. 18 When I sound my trumpet, accompanied by everyone who is with me, you must blow your trumpets all around the entire encampment. Then shout out, ‘For the LORD and for Gideon!’”
19 So Gideon and the 100 men with him arrived at the outer perimeter of the encampment at the beginning of the middle watch, just after they had posted sentries. They blew their trumpets and smashed the jars that they were carrying in their hands. 20 When the three companies sounded their trumpets and broke the jars, they held the torches in their left hands and sounded their trumpets with their right hands. Then they cried out, “A sword for the LORD and for Gideon!”