John Wesley on Joshua 6:21

Young and old - Being commanded to do so by the sovereign Lord of every man's life; and being informed by God before that the Canaanites were abominably wicked, and deserved the severest punishments. As for the infants, they were guilty of original sin, and otherwise at the disposal of their creator; but if they had been wholly innocent, it was a great favour to them to take them away in infancy, rather than reserve them to those dreadful calamities which those who survived them were liable to.