Joshua 7:2

2.And Joshua sent men from Jericho, etc To examine the site of the city and reconnoiter all its approaches was an act of prudence, that they might not, by hurrying on at random through unknown places, fall into an ambuscade. But when it would be necessary shortly after to advance with all the forces, to send forward a small band with the view of taking the city, seems to betray a want of military skill. Hence it would not have been strange that two or three thousand men, on a sudden sally were panic-struck and turned their backs. And it was certainly expedient for the whole body that twenty or thirty thousand should have spread in all directions in foraging parties. We may add, that even the act of slaying, though no resistance were offered, was of itself sufficient to wear out a small body of troops. Therefore, when the three thousand or thereabouts were repulsed, it was only a just recompense for their confidence and sloth. The Holy Spirit, however, declares that fewness of numbers was not the cause of the discomfiture, and ought not to bear the blame of it. The true cause was the secret counsel of God, who meant to show a sign of his anger, but allowed the number to be small in order that the loss might be less serious. And it was certainly a rare display of mercy to chastise the people gently and without any great overthrow, with the view of arousing them to seek an instant remedy for the evil. Perhaps, too, the inhabitants of Ai would not have dared to make an attack upon the Israelites had they advanced against the city in full force. The Lord therefore opened a way for his judgment, and yet modified it so as only to detect the hidden crime under which the people might otherwise have been consumed as by a lingering disease.

But although there is nothing wonderful in the defeat of the Israelites, who fought on disadvantageous terms on lower ground, it was, however, perfectly obvious that they were vanquished by fear and the failure of their courage before they came to close quarters; for by turning their backs they gave up the higher ground and retired to the slope of a valley. The enemy, on the other hand, showed how thoroughly they despised them by the confidence and boldness with which they ventured to pursue the fugitives at full speed in the direction of their camp. In the camp itself, such was the trepidation that all hearts melted. I admit, indeed, that there was cause for fear when, after having gained so many victories as it were in sport, they saw themselves so disgracefully defeated. In unwonted circumstances we are more easily disturbed. But it was a terror from heaven which dismayed them more than the death of thirty men and the flight of three thousand.