Charles Spurgeon Commentary Judges 7:19-21

"So Gideon, and the hundred men that were with him, came unto the outermost part of the camp in the beginning of the middle watch, when they had but newly set the watch: and they blew the trumpets, and brake in pieces the pitchers that were in their hands. And the three companies blew the trumpets, and brake the pitchers, and held the torches in their left hands, and the trumpets in their right hands wherewith to blow; and they cried, The sword of Jehovah and of Gideon. And they stood every man in his place round about the camp; and all the host ran; and they shouted, and put [them] to flight." — Judges 7:19-21 (ASV)

This was at the dead of night, when the hosts of Midian were fast asleep. They were startled from their slumbers by the blast of three hundred trumpets, and the flaming of three hundred torches.

They gathered that these were only the bugles and the lamps at the head of vast regiments of Israelites, and they hardly dared to calculate how great the whole host must be. Filled with fear, astonished at the sound of the trumpets, and the shouting of Gideon's band all round their camp, they took to their heels: all the host ran, and cried, and fled.