Albert Barnes Commentary Deuteronomy 20:10-20

"When thou drawest nigh unto a city to fight against it, then proclaim peace unto it. And it shall be, if it make thee answer of peace, and open unto thee, then it shall be, that all the people that are found therein shall become tributary unto thee, and shall serve thee. And if it will make no peace with thee, but will make war against thee, then thou shalt besiege it: and when Jehovah thy God delivereth it into thy hand, thou shalt smite every male thereof with the edge of the sword: but the women, and the little ones, and the cattle, and all that is in the city, even all the spoil thereof, shalt thou take for a prey unto thyself; and thou shalt eat the spoil of thine enemies, which Jehovah thy God hath given thee. Thus shalt thou do unto all the cities which are very far off from thee, which are not of the cities of these nations. But of the cities of these peoples, that Jehovah thy God giveth thee for an inheritance, thou shalt save alive nothing that breatheth; but thou shalt utterly destroy them: the Hittite, and the Amorite, the Canaanite, and the Perizzite, the Hivite, and the Jebusite; as Jehovah thy God hath commanded thee; that they teach you not to do after all their abominations, which they have done unto their gods; so would ye sin against Jehovah your God. When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by wielding an axe against them; for thou mayest eat of them, and thou shalt not cut them down; for is the tree of the field man, that it should be besieged of thee? Only the trees of which thou knowest that they are not trees for food, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it fall." — Deuteronomy 20:10-20 (ASV)

Directions intended to prevent wanton destruction of life and property in sieges.

(Deuteronomy 20:16) Forbearance, however, was not to be shown toward the Canaanite nations, which were to be utterly exterminated . The command did not apply to beasts as well as men (Compare to Joshua 11:11, Joshua 11:14).

(Deuteronomy 20:19) The parenthesis may be more literally rendered for man is a tree of the field, that is, he has his life from the tree of the field and is supported in life by it . The Egyptians seem invariably to have cut down the fruit-trees in war.