“When you draw near to a city to fight against it, offer terms of peace to it.
10. When thou goest forth to war. He now teaches that, even in lawful wars, cruelty is to be repressed, and bloodshed to be abstained from as much as possible. He therefore commands that, when they shall have come to take a city, they should first of all exhort its inhabitants to obtain peace by capitulating; and if they should do so, to keep them...
They are here directed what method to take in dealing with the cities (these only are mentioned, Deu 20:10, but doubtless the armies in the field, and the nations they had occasion to deal with, are likewise intended) upon which they made war.
Commenting on Deuteronomy 20:10-20
When thou comest nigh unto a city to fight against it,.... This is to be understood of an arbitrary war, as Jarchi observes; which they engaged in of themselves, or were provoked to by their enemies; which was their own choice, and according to their own will and pleasure; and their conduct towards their enemies in it was different from that in a war with...