John Calvin Commentary Deuteronomy 20:12

"And if it will make no peace with thee, but will make war against thee, then thou shalt besiege it:" — Deuteronomy 20:12 (ASV)

And if he will make no peace. The permission given here seems to grant too much license; for, since pagan writers⁴⁶ command even the conquered to be spared, and instruct that those should be admitted to mercy who lay down their arms and entrust themselves to 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, authorize indiscriminate bloodshed?

It has already been stated that more was conceded to the Jews because of their hardness of heart than was justly lawful for them. Undoubtedly, by the law of charity, even armed men should be spared if, throwing down the sword, they ask for mercy; in any case, it was not lawful to kill anyone except those who were captured in arms, with sword in hand.

This permission, therefore, to slaughter, which extends to all the males, is far from perfect.⁴⁷ But, although in their ferocity the Jews would have hardly allowed the perfection of equity to be prescribed to them, still God would at least restrain their excessive violence from reaching the extreme of cruelty. This applies to cities taken by force, where it sometimes happens that no distinction of sex or age is respected; this inhumanity is mitigated here, since they were not allowed to kill women or children.

⁴⁶ “Et cum iis, quos vi deviceris, consulendum est; tum 2, qui, armis positis, ad imperatorum fidem confugient, quamvis murum aries percusserit, recipiendi sunt.” — Cic, de Off. 1:11.

⁴⁷ Addition in Fr., “et equite qui doit estre en tous enfans de Dieu;” and from the equity which ought to be in all God’s children.., “et equite qui doit estre en tous enfans de Dieu;” and from the equity which ought to be in all God’s children.