So Joshua smote all the country of the hills, and of the south, and of the vale, and of the springs, and all their kings: he left none remaining, but utterly destroyed all that breathed, as the LORD God of Israel commanded.
God's command stands as the sole answer to any charge of cruelty here. Joshua could not have done otherwise than obey; he was the instrument of divine judgment, not a man acting on his own. When you hear that he slew all without distinction, your mind should stop questioning once you learn God commanded it, as surely as it accepts a judge pronouncing sentence on the guilty.
AI summary
A good general knows how to follow up a victory, and Joshua seized his moment: he took six cities in swift succession, destroyed the armies sent to relieve them, and brought the whole southern country under Israel's hand. His failure to take Jerusalem and Jarmuth at once was a missed opportunity they would pay dearly to recover later.
AI summary
Commenting on Joshua 10:28-43
And Joshua smote them, from Kadeshbarnea,.... Which lay to the south of the land of Canaan, Num 13:17, even unto Gaza, which lay to the southwest, and was one of the five principalities of the Philistines; of which city See Gill on Amo 1:7; and See Gill on Act 8:26, and all the country of Goshen, even unto Gibeon; to which he returned back in...