Deuteronomy 20

9. they shall make captains of the armies to lead the people--When the exempted parties have withdrawn, the combatants shall be ranged in order of battle.

10-20. When thou comest nigh unto a city to fight against it, then proclaim peace unto it--An important principle is here introduced into the war law of Israel regarding the people they fought against and the cities they besieged. With "the cities of those people which God doth give thee" in Canaan, it was to be a war of utter extermination ( Deuteronomy 20:17 Deuteronomy 20:18 ). But when on a just occasion, they went against other nations, they were first to make a proclamation of peace, which if allowed by a surrender, the people would become dependent ( Deuteronomy 20:11 ), and in the relation of tributaries the conquered nations would receive the highest blessings from alliance with the chosen people; they would be brought to the knowledge of Israel's God and of Israel's worship, as well as a participation of Israel's privileges. But if the besieged city refused to capitulate and be taken, a universal massacre was to be made of the males while the women and children were to be preserved and kindly treated ( Deuteronomy 20:13 Deuteronomy 20:14 ). By this means a provision was made for a friendly and useful connection being established between the captors and the captives; and Israel, even through her conquests, would prove a blessing to the nations.

19. thou shalt not destroy the trees thereof by forcing an axe against them--In a protracted siege, wood would be required for various purposes, both for military works and for fuel. But fruit-bearing trees were to be carefully spared; and, indeed, in warm countries like India, where the people live much more on fruit than we do, the destruction of a fruit tree is considered a sort of sacrilege.

20. thou shalt build bulwarks against the city that maketh war with thee--It is evident that some sort of military engines were intended; and accordingly we know, that in Egypt, where the Israelites learned their military tactics, the method of conducting a siege was by throwing up banks, and making advances with movable towers, or with the testudo [WILKINSON].