three companies: This small number of men, thus divided, would be able to encompass the whole camp of the Midianites. Concealing the lamps in the pitchers, they would pass unobserved to their appointed stations; then, in the dead of the night, when most of the enemy were fast asleep, all at once breaking their pitchers one against another, with as much noise as they could, and blowing the trumpets and shouting; they would occasion an exceedingly great alarm. The obedience of faith alone could have induced such an expedient, which no doubt God directed Gideon to employ. - Scott.
a trumpet: Heb. trumpets in the hand of all of them
empty: 2 Corinthians 4:7
lamps: or, fire-brands, or torches