The Lord Goes Before You Into Battle, Deuteronomy 9-10.

Deuteronomy 9:3-6 Therefore understand today that the Lord your God is He who goes over before you as a consuming fire. He will destroy them and bring them down before you; so you shall drive them out and destroy them quickly, as the Lord has said to you. “Do not think in your heart, after the Lord your God has cast them out before you, saying, ‘Because of my righteousness the Lord has brought me in to possess this land’; but it is because of the wickedness of these nations that the Lord is driving them out from before you. It is not because of your righteousness or the uprightness of your heart that you go in to possess their land, but because of the wickedness of these nations that the Lord your God drives them out from before you, and that He may fulfill the word which the Lord swore to your fathers, to Abraham, Isaac, and Jacob. Therefore understand that the Lord your God is not giving you this good land to possess because of your righteousness, for you are a stiff-necked people.