Deu 2:16-23 “So as soon as all the men of war had perished and were dead from among the people, the LORD said to me, ‘Today you are to cross the border of Moab at Ar. And when you approach the territory of the people of Ammon, do not harass them or contend with them, for I will not give you any of the land of the people of Ammon as a possession, because I have given it to the sons of Lot for a possession.’ (It is also counted as a land of Rephaim. Rephaim formerly lived there—but the Ammonites call them Zamzummim— a people great and many, and tall as the Anakim; but the LORD destroyed them before the Ammonites, and they dispossessed them and settled in their place, as he did for the people of Esau, who live in Seir, when he destroyed the Horites before them and they dispossessed them and settled in their place even to this day. As for the Avvim, who lived in villages as far as Gaza, the Caphtorim, who came from Caphtor, destroyed them and settled in their place.)
When all the men of war were consumed — Israel is not called to march against and attack the Canaanites till the men most fit for war, and who probably had learned the art of it in Egypt, and had been used to hardship, were all wasted and dead from among the people, and only a host of new raised men, trained up in a wilderness, were left, in whom, as being possessed of little knowledge, experience, or natural fortitude, no great dependance could be placed. Thus it became more fully manifest that the excellency of the power which subdued the warlike Canaanites, was of God and not of man. On the same principle, and with the same design, long after this, were the following words spoken by the Lord to Gideon: The people that are with thee are too many for me to give the Midianites into their hands, lest Israel vaunt themselves against me, saying, Mine own hand hath saved me. And thus, to subdue the enemies of God’s church, and bring sinners to the obedience of the faith, he hath chosen the weak things of the world, and things that are despised, and things that are not, to bring to naught the things that are, that no flesh may glory in his presence. (Benson)