If Israel prevails against Midian by sheer force of their numbers, then they will fail to recognize God's pivotal role. But if Israel prevails against the Midianite hordes, with a tiny force, then God's involvement will be undeniable.
While earlier judges had to contend with challenges at least as great as that of Gideon, none merited quite the same degree of Divine hand-holding that Gideon received. This highlights the measure of his own limited spiritual resources to be able to do so unassisted. However, if the caliber of the shoftim decreases as the book progresses, it is also an indictment of the spiritual state of the people of Israel.
The noise of the smashing jars, the blare of the shofarot and the outcry of the Israelite force, the burning torches that suddenly appear out of the darkness, the enemy forces that attack from three directions simultaneously, combined with the belief that Gideon has a colossal army at his disposal, causes the Midianites to flee.
