As the final act of battle, Israel was sometimes required to dedicate everything in a “ban” (herem), which meant that the people and possessions of an entire city would be set apart for God and destroyed (Deut 7:2; 20:17; Josh 8:2; 1 Sam 15:3). Only the metal objects were saved (Josh 6:18-24). Those who transgressed the ban faced dire consequences (Josh 7).
Why would a loving God order the wholesale extermination of the nation’s living in the promised land? There is no simple answer to this difficult question. Three points, however, need to be remembered. First, the concept of the ban is also found among the nations surrounding Israel. In war, every living being, and every piece of property was to be dedicated to the deity. Second, the rules for placing the spoils of war under the ban appear to apply only to the cities of the nations within the promised land that God had designated as inheritance for Israel (Deut 20:16-18).
In this context, it should be noted that the OT reports the use of the ban primarily at Arab (Num 21:2-3), the cities of Sihon and Og (Deut 2:24; 3:6), Jericho (Josh 6:21), Ai (Josh 8:26), the cities of southern Canaan (Josh 10:28-43) and Hazor (Josh 11:11). Finally, it must be remembered that Israel was only allowed to drive out the nations living in the promised land because of their sinful abominations (Deut 9:4-5; 18:9-14; 20:16-18). In this sense, Israel served as the instrument of God’s judgment against these sinful nations. In like manner, God would later allow another nation to march against Judah in judgment.