20 For it was of Yahweh to harden their hearts, that they should come against Israel [Yisroel]in battle [milchamah], that he might destroy them utterly, and that they might have no favour [techinnah (mercy plea)], but that he might destroy them, as Yahweh commanded Moses [Moshe].

This, however, would not be obviously miraculous. The nations would simply exhibit that disposition of reckless disregard, which is by no means an uncommon spectacle among mankind. There would, nevertheless, be a difference. The common indiscretions of men are due to what they are in themselves, while this would be generated by divine influence operating upon them, as came to pass in the case of Israel themselves afterwards in later ages, when, as Josephus testifies, the Jews seemed to act under a divine fury, impelling them to such wild attitudes and courses towards the Romans, as brought on their complete destruction.

Visible Hand of God

In prosecuting the campaign after the fall of Jericho, Joshua showed a disposition in some instances to treat amicably with the hostile inhabitants. Had they met his advances in a reasonable way, it would probably have resulted that some of them, at least, would have been spared the destruction that came upon them. But this would have been contrary to the divine purpose and intent. It was effectually prevented by God's incitement of the Canaanites to oppose.

Ways of Providence ch 12