Therefore shalt thou make them turn their back, when thou shalt make ready thine arrows upon thy strings against the face of them. Therefore shalt thou make them turn their back - God can in a moment strike the most powerful and numerous army, even in the moment of victory, with panic; and then even the lame, the army which they had nearly routed, shall take the prey, and divide the spoil.
Against the face of them - Thou shalt cause them to turn their backs and fly, as if a volley of arrows had been discharged in their faces. This seems to be the sense of this difficult verse.