Verse 1
Deuteronomy 20:1. When thou goest out to battle against thine enemies — The land of Canaan being to be gained by conquest, in a war of God’s special appointment; and the Israelites, after their settlement in it, being likely to be exposed to invasions from, or quarrels with the neighbouring nations, Moses judged it necessary to leave them some standing rules for their conduct in both these kinds of war. The first and great rule was, to commit their cause to God, depending with entire confidence upon that divine power which had so often and so wonderfully delivered them, without the least fear or discouragement at the superior force or terrible appearance of their enemies. And seest horses and chariots — The armies of the Israelites consisted wholly of foot, and their law seems to have obliged them to continue so, in order that their reliance might be entirely on God, Deuteronomy 17:16. But the Egyptians, Canaanites, and other nations, had the advantage of horses and chariots, in which they placed their confidence. Thus the psalmist: “Some trust in chariots and some in horses, but we will remember the name of the Lord our God.” These chariots were sometimes armed with scythes, to rush in among the foot, and cut them down like grass, which made them very formidable. These are the chariots of iron, mentioned 4:3.

Verse 2
Deuteronomy 20:2. The priest shall approach — The Jews say there was a priest anointed for the purpose, whose office, as we may gather from Numbers 31:6, was to blow with the trumpet when they were preparing for battle. And shall speak to the people — Probably exhorting them, in the most persuasive manner, to a courageous and undaunted performance of their duty, considering their cause as God’s, and relying on his protection and aid.

Verse 5-6
Deuteronomy 20:5-6. What man is there — This and the following exceptions are to be understood only of a war allowed by God, not in a war commanded by God, not in the approaching war with the Canaanites, from which even the bridegroom was not exempt, as the Jewish writers note. Hath planted a vineyard — This and the former dispensation were generally convenient, but more necessary in the beginning of their settlement in Canaan, for the encouragement of those who should build houses or plant vineyards, which were chargeable to them, and beneficial to the commonwealth. Eaten of it — Hebrew, made it common; namely, for the use of himself, and family, and friends, which it was not till the fifth year.

Verse 7-8
Deuteronomy 20:7-8. Hath betrothed a wife — The time allowed in this case was a year, Deuteronomy 24:5. This was a law of great humanity, that conjugal love might not be disturbed, but have time to knit into a firm and lasting affection. What man is fearful and faint-hearted — This fearfulness is to be understood, say the Jews, not only of a natural timorousness, which is incident to some constitutions, and makes a man tremble at every danger, but of the adventitious terrors of a guilty conscience. For they did not, as in the modern fashion, send the wickedest and most worthless into the wars; but if they knew any man to be a notorious villain, they thrust him out of the army, lest his example should corrupt and discourage the rest of the soldiery.

Verse 9
Deuteronomy 20:9. They shall make captains — Or rather, as the Hebrew is, they shall set or place the captains of the armies in the head or front of the people under their charge, that they may conduct them, and, by their example, encourage their soldiers. It is not likely they had their captain to make when they were just going to battle.

Verse 16
Deuteronomy 20:16. Thou shalt save alive nothing — No human creature; for the beasts, some few excepted, were given for a prey. This slaughter of all the people is to be understood only in case they did not surrender when summoned, but rejected the conditions of peace when offered them. In which case their condition was worse than that of any other people, whose males only were to be slain, Deuteronomy 20:14.

Verse 18
Deuteronomy 20:18. That they teach you not to do after all their abominations — Here is the great reason for the aforesaid severe execution; they were most abominable idolaters, who offered their children to Moloch; they were magicians, wizards, necromancers, and guilty of all those abominations and filthy lusts mentioned Leviticus 18. So that God thought them not fit to live any longer upon the face of the earth; for had they been spared, after obstinately rejecting terms of peace, they would undoubtedly have sought to infect the Israelites with their filthy idolatry; and it was mercy to the human race in general not to suffer such a wicked, contagious generation to subsist. From the words here quoted, That they teach you not, &c., a Jewish writer justly observes, “If they repented and forsook their idolatry, the Israelites might let them live;” for then there was no such danger in sparing them. Accordingly Rahab, her father, mother, brethren, and all her kindred, were preserved alive, and so were the Hivites or Gibeonites, on condition of servitude, which they themselves offered, Joshua 9:11-15. See Joshua 11:11-20; Jeremiah 18:7-8.

Verse 19
Deuteronomy 20:19. Thou shalt not destroy the trees — Which is to be understood of a general destruction of them, not of cutting down some few of them, as the convenience of the siege might require. Man’s life — The sustenance or support of his life.