The remarkable military triumphs of the Israelites were never a matter of numbers or battlefield strategy. Instead, these sweeping victories were the direct result of God stepping in and fighting on their behalf.
Throughout the wars that secured the land, the sheer scale of their success defied human logic. A single Israelite warrior could send a thousand enemies fleeing in defeat. Rather than being a promise for future battles, this simply describes the reality of what already happened during their campaigns. Because of God's active involvement, everyday individuals achieved impossible feats against overwhelming odds in the conflicts they had already fought and won [רד״ק, מצודת דוד].