Bible Notes Online - Deuteronomy 20 - ESV
Commentary

v1: The Israelites had no horses and no chariots, and comparatively few soldiers; but they had to trust in God. The promise was His presence.

v2-4: The priest had the task of reminding the people of the truth of God's presence, and the promise therefore of victory.

v5-7: valid reasons were presented for not fighting; contrast Luke 14.18-20, where people made excuses for not following Jesus. The Lord looks for single-mindedness (2 Tim 2.4); we are to beware distractions.

v8: Some would be fearful. They were sent home, so that they did not discourage others. Fear is contagious. See 1 Sam 13.7-10, when Saul's army started to scatter from him.

 

v9: Delegated leadership was a mark of the Israelites.

v10-15:   Cities outside Canaan are offered peace. The reasons for war are not given; it is simply a reality of human life.

v16-18: Clear reasons were given for destroying the Canaanite peoples. Had they remained alive, they would influence the Israelites, and encourage them to disobey God. The Book of Judges records how the commands here were not fully obeyed, and how the Israelites were led astray. The consequences were severe, as they suffered under the dominion of foreign kings.

v19-20: In a siege, the people were not to destroy fruit trees, as they would provide for the people at a later time; practical advice.