Deuteronomy 20:10

Instructions Concerning Sieges. - Deu 20:10, Deu 20:11. On advancing against a town to attack it, they were "to call to it for peace," i.e., to summon it to make a peaceable surrender and submission (cf. Jdg 21:13). "If it answered peace," i.e., returned an answer conducing to peace, and "opened" (sc., its gates), the whole of its inhabitants were to become tributary to Israel, and serve it; consequently even those who were armed were not to be put to death, for Israel was not to shed blood unnecessarily. מס does not mean feudal service, but a feudal slave (see at Exo 1:11).

They are here directed what method to take in dealing with the cities (these only are mentioned, Deu 20:10, but doubtless the armies in the field, and the nations they had occasion to deal with, are likewise intended) upon which they made war. They must not make a descent upon any of their neighbours till they had first given them fair notice, by a public manifesto, or remonstrance, stating the ground of their quarrel with them. In dealing with the worst of enemies, the laws of justice and honour must be observed; and, as the sword must never be taken in hand without cause, so not without cause shown. War is an appeal, in which the merits of the cause must be set forth. I. Even to the proclamation of war must be subjoined a tender of peace, if they would accept of it upon reasonable terms. That is (say the Jewish writers), "upon condition that they renounce idolatry, worship the God of Israel, as proselytes of the gate that were not circumcised, pay to their new masters a yearly tribute, and submit to their government:" on these terms the process of war should be stayed, and their conquerors, upon this submission, were to be their protectors, Deu 20:10, Deu 20:11. Some think that even the seven nations of Canaan were to have this offer of peace made to them; and the offer was no jest or mockery, though it was of the Lord to harden their hearts that they should not accept it, Jos 11:20. Others think that they are excluded (Deu 20:16) not only from the benefit of that law (Deu 20:13) which confines military execution to the males only, but from the benefit of this also, which allows not to make war till peace was refused. And I see not how they could proclaim peace to those who by the law were to be utterly rooted out, and to whom they were to show no mercy, Deu 7:2. But…

20:10-15 The people in the land had already been placed under the ban (7:1-6), so this instruction refers to those whom Israel would engage outside the land (20:15).