The rules of military engagement were different depending on whether the city was outside the boundaries or one of the cities within the land of Canaan. There were also different rules of engagement for certain cities that were “dedicated to destruction” such as Jericho.
A. For cities outside the boundaries of Canaan, 10-15
“When you approach a city to fight against it, you shall offer it
terms of peace. If it agrees to make peace with you and opens to you,
then all the people who are found in it shall become your forced labor
and shall serve you. However, if it does not make peace with you, but
makes war against you, then you shall besiege it. When the Lord your
God gives it into your hand, you shall strike all the men in it with
the edge of the sword. Only the women and the children and the animals
and all that is in the city, all its spoil, you shall take as booty
for yourself; (The women and children would have been taken as forced
labor, though some women were taken as wives.) and you shall use the
spoil of your enemies which the Lord your God has given you. Thus, you
shall do to all the cities that are very far from you, which are not
of the cities of these nations nearby."
B. For cities within Canaan’s boundaries, 16-18
“Only in the cities of these peoples that the Lord your God is giving
you as an inheritance, you shall not leave alive anything that
breathes. But you shall utterly destroy them, the Hittite and the
Amorite, the Canaanite and the Perizzite, the Hivite and the Jebusite,
as the Lord your God has commanded you, so that they may not teach you
to do according to all their detestable things which they have done
for their gods, so that you would sin against the Lord your God.”
The first thing that must be understood from these verses is that these rules of engagement which offered terms of peace pertained ONLY to those cities that were outside the boundaries of Canaan. Offering conditions of peace did not apply to those nations within the land of Canaan. Indeed, it was not even considered to be an option by the Lord. Those cities were to be utterly destroyed with no quarter given to its inhabitants. Concerning the inhabitants of those cities, the Lord commanded, “you shall not leave alive anything that breathes.” This of course refers to human inhabitants. When you follow Joshua’s exploits during the conquest you see time and again that Joshua left none alive when he attacked a city. He consistently killed every man woman and child. He did however take their cattle and other spoils of war, which every man was free to do, and hamstrung their horses. Only with a city under ban was the livestock slaughtered and plunder forbidden, as was the case with Jericho. At Jericho, they
“utterly destroyed everything in the city, both man and woman, young
and old, and ox and sheep and donkey, with the edge of the sword.” …
“Only the silver and gold, and articles of bronze and iron, they put
into the treasury of the house of the Lord.”
This was done according to Joshua's instructions in verse 19 before the assault on the city began.
Offering terms of peace to those cities “very far from you” was a required provision from the Lord. They were not to attack such a city without first making an attempt at peace. If the city agreed to the conditions of peace, that city would then become a tributary to Israel and serve Israel as forced laborers. Israel was to be a light to these nations bringing to them the knowledge of Jehovah.