John Calvin Commentary Joshua 11:12

"And all the cities of those kings, and all the kings of them, did Joshua take, and he smote them with the edge of the sword, and utterly destroyed them; as Moses the servant of Jehovah commanded." — Joshua 11:12 (ASV)

And all the cities of those kings, etc. Having routed the army, they began to plunder and lay waste the country, and to take and demolish the towns. From its being said that the cities which remained entire were not burned, it may be inferred with some probability that some were taken by force and assault, and so razed.

Hazor, alone, after the siege was over, and the heat of the struggle had cooled, was destroyed by fire because it had held forth the torch which enkindled the war. But in accordance with the explanation already given, it is repeatedly and more clearly stated in this passage that Joshua did not give loose reins to his passion when he slew all from the least to the greatest.

For there is now a distinct statement of what had not yet been expressed, namely, that Joshua faithfully performed his part by fulfilling everything which the Lord had enjoined by Moses. It is just as if he had placed his hands at the disposal of God when he destroyed those nations according to his command.

And so we ought to hold that, though the whole world should condemn us, it is sufficient to free us from all blame, that we have the authority of God. Meanwhile, we should prudently consider what each person’s vocation requires, lest anyone, by giving license to his zeal, wishing to imitate Joshua, may be judged cruel and bloodthirsty, rather than a strict servant of God.