Deuteronomy 20:12

12.And if he will make no peace. The permission here given seems to confer too great a license; for, since heathen writers (46) command even the conquered to be spared, and enjoin that those should be admitted to mercy who lay down their arms, and cast themselves on the good faith of the General, although the battering-ram may have actually made a breach in the wall, how does God, the Father of mercies, give His sanction to indiscriminate bloodshed? It has already been stated, that more was conceded to the Jews on account of their hardness of heart, than was justly lawful for them. Unquestionably, by the law of charity, even armed men should be spared, if, casting away the sword, they crave for mercy; at any rate it was not lawful to kill any but those who were taken in arms, and sword in hand. This permission, therefore, to slaughter, which is extended to all the males, is far distant from perfection. (47) But, although in their ferocity the Jews would have hardly suffered the perfection of equity to be prescribed to them, still God would at least restrain their excessive violence from proceeding to the extremity of cruelty. The question is as to cities taken by force, where it sometimes happens that there is no distinction of sex or age regarded; this inhumanity is here mitigated, since they might not kill either women or children.