Ver. 12, 13. If it will make no peace—thou shalt smite every male— To punish their obstinacy for rejecting peace, and for incurring all those horrors of war, which, no doubt, they were taught to expect if they refused the conditions offered.
Related Commentaries of Deuteronomy 20:12
Deuteronomy 20:12-13
12 And if it will make no peace with thee, but will make war against thee, then thou shalt besiege it:
13 And when the LORD thy God hath delivered it into thine hands, thou shalt smite every male thereof with the edge of the sword: