Deuteronomy 20:10

When you come nigh to a city to make war against it, then you shall send to it certain to invite it to peace;

Presumably, the commandment to “offer it peace” only applies to an optional war [see Sifrey on this verse] [see also Palestinian Talmud Shvi‘it 6: 1; the authorities disagree regarding this halakha — Translator].

WHEN THOU DRAWEST NEAR UNTO A CITY TO FIGHT AGAINST IT, THEN PROCLAIM PEACE UNTO IT. “Scripture is speaking of a permissible war [rather than a war required by the Torah, such as the invasion of the seven nations of Canaan], as it is expressly stated in this section, Thus shalt thou do unto all the cities which are very far off from thee.” This is Rashi’s language. The Rabbi [Rashi] wrote this based on the Sifre where a similar text is taught: 199. “Scripture is speaking of a battle waged of free choice.” But the intent of our Rabbis with reference to this verse [before us, was not to say that the requirement of proclaiming peace applies exclusively to permissible, but not to obligatory, wars; rather, their teaching in the Sifre] refers only to the later section wherein there is a differentiation between the two kinds of wars [i.e., in Verses 13-14 declaring that if the enemy insists on war, then only the men are to be killed, but the women and children are to be spared — that law applies only to a permissible but not to an obligatory war]. But the call for peace applies even to an obligatory war. It requires us to offer peace-terms even to the seven nations [of Canaan], for Moses proclaimed peace to Sihon, king of the Amorites, and he would not have transgressed both the positive and negative commandments in this section: but thou shalt utterly destroy them, and thou shalt save alive nothing that breatheth! Rather, the difference between them [i.e., obligatory and permissible wars] is when the enemy does not make peace and continues to make war. Then, in the case of the cities which are very far off, Scripture commanded us to smite every male thereof and keep alive the women and male children, but in the cities of these peoples [i.e., the seven nations of Canaan in the event they refuse the call to peace], it commanded us to destroy even the women and children. And so did our Rabbis say in the Midrash of Eileh Hadevarim Rabbah, and it is found also in Tanchuma 18. and in the Gemara Yerushalmi: “Rabbi Shmuel the son of Rabbi Nachmani said: Joshua the son of Nun fulfilled the laws of this section. What did Joshua do? Wherever he went to conquer, he would send a proclamation in which he wrote: ‘He who wishes to make peace let him come forward and make peace; he who wishes to leave, let him leave, and he who wishes to make war, let him make war.’ The Girgashite left. With the Gibeonites who made peace, Joshua …

וקראת אליה לשלום, “you shall first offer peace to that city. According to some sages the rule mentioned here even included nations who the Israelites had been ordered by G–d to kill every “soul.” However, this command did not apply if the inhabitants agreed to vacate the town and relocate outside the Holy Land. We know that peace is superior to war, i.e. hostility, from when G–d Himself changed what Sarah had thought about her husband when she considered him too old to impregnate her with effective sperm. (Genesis18,12) He did not tell him about that part of her reaction to the angel’s prediction that by the following year she would have a son. We have a verse in Hoseah 4,17: חבור עצבים אפרים הנח לו, “Ephrayim is addicted to images,- let him be.” This verse is quoted by Rashi in connection with the verse we just quoted from Genesis, where he says that this cannot be understood at face value, i.e. that the prophet should not predict doom for idol worshippers. Our author cites several additional examples of where we cannot take a quotation at face value, especially when the brothers after Yaakov’s funeral quote their father as having commanded them to ask Joseph for forgiveness. (Genesis 50,17) The Torah wrote this in order to preserve harmony between Joseph and his brothers, not because Yaakov had actually said these words. Both the blessings by the priests end with bestowing the blessing of peace and the last of the 19 benedictions in the amidah prayer that we recite at least three times daily, concludes with the blessing of shalom, peace. Our sages in the Talmud, tractate Gittin folio 61, bid us to greet a gentile with the blessing of shalom before waiting for him to greet us, and in the event that he does to respond with using the expression shalom twice. Seeing that this might appear insincere on our part, the Talmud urges us to greet him before he can greet us so that we can avoid using the word shalom twice when greeting him, something that is forbidden in the Talmud, tractate Gittin folio 62. On folio 59 in the same tractate we are also told not to accept something that had been found by a deaf person or a minor, as it might have come into his possession illegally. We are also to feed the poor of the gentiles, all in order to maintain harmonious relations with the gentiles, generally. For all these reasons Hashem blessed His people with shalom (Psalms 29.11)