And if it will make no peace with thee, but will make war against thee, then thou shalt besiege it:

But if they will not make peace, and shall begin war against thee, thou shalt besiege it.

'And if it doth not make peace with thee, and hath made with thee war, then thou hast laid siege against it,

If however it will not make peace with you, but war, then let it be shut in on all sides:

But if they are not willing to enter into an agreement, and they begin to act against you in warfare, then you shall besiege it.

Si vero pacem non fecerit tecum, sed faciet tecum praelium, obsederisque eam;

And if he will make no peace. The permission here given seems to confer too great a license; for, since heathen writers [1] 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. 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.

Footnotes

1 - "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.

And if it will make no peace with thee,.... Will not accept of terms of peace offered:
but will make war against thee; come out and fight, or prepare to defend themselves: then thou shall besiege it; surround and block it up on all sides with their forces; the Jews say only on three sides, leaving one for any to flee and make their escape if they thought fit; See Gill on Numbers 31:7.

If the hostile town, however, did not make peace, but prepared for war, the Israelites were to besiege it; and if Jehovah gave it into their hands, they were to slay all the men in it without reserve ("with the edge of the sword," see at Genesis 34:26); but the women and children and all that was in the city, all its spoil, they were to take as prey for themselves, and to consume (eat) the spoil, i.e., to make use of it for their own maintenance.