Bnei Yisrael Mastering Peace
בפסוק כי תקרב א"ע כו' וקראת אלי' לשלום כו' ובמד' ותגזר אומר ויקם כו'
On the pasuk, "When you draw near to a city to wage war against it, you shall call out to it for peace" (Devarim 20:10), and the Midrash brings the verse, "You will decree a matter and it will be fulfilled" (Iyov 22:28).
The Sfas Emes opens with the Torah's command to first offer peace to a city before waging war, linking it to the Midrash's verse that a tzaddik's decree is fulfilled.
הענין הוא כי יש לבנ"י כח לקרב כל האומות אם היו חפצים להכניע עצמם תחת בנ"י לכן נקראו בנ"י השולמית
The idea is that Bnei Yisrael possess the power to draw all the nations close, if those nations would desire to subordinate themselves beneath Bnei Yisrael; therefore Bnei Yisrael are called "the Shulamis" (the one of peace).
Bnei Yisrael have the inner power to bring even the nations close to kedushah, provided those nations submit themselves; for this reason Bnei Yisrael bear the name connected to shalom.
כביכול כמו שהקב"ה עושה שלום במרומיו מלך שהשלום שלו
As it were, just as the Holy One, Blessed is He, makes peace in His heights, the King to whom peace belongs,
Just as Hashem, the King to whom peace belongs, establishes peace among the heavenly hosts above,
כן בנ"י למטה נק' השולמית שהשלום ברשותם
so too Bnei Yisrael below are called "the Shulamis," for peace is within their domain.
so Bnei Yisrael below carry that same name of peace, because peace is placed under their control and within their power.
וזה הברכה שכ' ה' יברך א"ע בשלום
And this is the berachah that is written, "Hashem shall bless His people with peace" (Tehillim 29:11).
This explains the berachah in Tehillim that Hashem blesses Bnei Yisrael specifically with the gift of peace.
וזהו ותגזר אומר כו' כי הגם שבוודאי אותן האומות אשר נלחמים עם בנ"י המה רשעים וצריכין לאבד אותם
And this is the meaning of "You will decree a matter," for although it is certainly true that those nations who wage war against Bnei Yisrael are wicked and must be destroyed,
The verse "you will decree a matter" applies here: even though the enemy nations are genuinely wicked and deserving of destruction,
עכ"ז וקראת כו' לשלום
nevertheless, "you shall call out to it for peace."
the Torah still commands that one first call out to them with an offer of peace.
והי' כו' לך למס כו' ועי"ז יוכל להיות התיקון:
"And it shall be, if it answers you with peace... it shall become a tributary to you" (Devarim 20:11), and through this the tikkun can come about.
If the nation accepts and submits as a tributary, then a tikkun and elevation can be accomplished through that very submission.
Summary: The Sfas Emes teaches that Bnei Yisrael possess the power to draw even the nations of the world close to kedushah, provided those nations are willing to subordinate themselves. For this reason Bnei Yisrael are called "the Shulamis," the people of peace, for just as Hashem is the King to whom peace belongs and who makes peace in His heights, so too peace rests within the domain of Bnei Yisrael below. This is the meaning of the berachah, "Hashem shall bless His people with peace." Therefore, even though the enemy nations are wicked and ultimately deserving of destruction, the Torah commands that one first call out to them with an offer of peace; and if they answer with peace and become a tributary, a tikkun is achieved through that submission.