Making Peace With Yetzer Hara
בפסוק כי תקרב כו' וקראת כו' לשלום
Regarding 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),
The Sfas Emes opens with the pasuk in our parsha that commands offering peace to a city before besieging it in war.
יש לפרש גם על מלחמת היצה"ר שמקודם צריכין לחפוץ להשלים עמו כפי תנאי הכתוב יהיו לך למס שיניח ליתן חלק להשי"ת מכל דבר
it can also be explained as referring to the war against the yetzer hara: that at first one must seek to make peace with it, in accordance with the condition stated in the pasuk, "They shall be a tribute to you" (Devarim 20:11) - that it should allow a portion to be given to Hashem from everything.
He reads this on a deeper level as guidance for confronting the yetzer hara: rather than going straight to battle, one first tries to make peace with it on Hashem's terms, namely that the yetzer hara consent to a portion of every act being dedicated to Hashem.
ובכח זה יתהפך גם הוא לעבד
And through this power, even the yetzer hara itself becomes turned into a servant.
When the yetzer hara is engaged this way, its own energy is converted into a force that serves Hashem.
וזה הדרך מרוצה ביותר
And this is the path that is most desirable.
This approach - harnessing the yetzer hara rather than only fighting it - is the preferred and smoothest path in avodas Hashem.
לכן כתי' והי' אם שלום תענך
Therefore it is written, "And it shall be, if it answers you in peace" (Devarim 20:11),
The Sfas Emes anchors this in the wording of the pasuk that speaks of the city answering "in peace."
שהוא לשון שמחה
for this is a term of joy.
He notes that "shalom" here carries a connotation of joy, since serving Hashem with the yetzer hara enlisted brings simchah.
רק אם רואין שאינו מניח לעבוד ה'
Only if one sees that it does not allow him to serve Hashem,
However, there is a limit: if the yetzer hara refuses to permit any avodas Hashem at all,
צריכין לברוח מידו גם לצאת מדרך הממוצע
then one must flee from its grasp, even to depart from the middle path.
then peace is no longer an option, and a person must flee from it entirely, even abandoning the balanced middle path in order to escape.
ובאמת ברצות ה' דרכי איש גם אויביו ישלים את לכן בתחלה קודם שחוטאין יכולין להיות בשלום עמו
And in truth, "When Hashem favors a man's ways, He makes even his enemies be at peace with him" (Mishlei 16:7) - therefore at the outset, before one sins, one is able to be at peace with it.
Citing Mishlei, he explains that when a person's ways are pleasing to Hashem, even his enemies - including the yetzer hara - are reconciled to him, so before a person sins he is still able to live at peace with his yetzer.
אחר כך מצאתי באוה"ח מזה:
Afterward I found this matter discussed in the Ohr HaChaim:
The Sfas Emes closes by noting that he later found the Ohr HaChaim addressing this same idea.
Summary: Reading the parsha's command to offer peace to a city before war as a teaching about the battle with the yetzer hara, the Sfas Emes explains that one should first seek peace with the yetzer hara on Hashem's terms - that it permit a portion of every act to be devoted to Hashem. When the yetzer hara is engaged this way, its own energy is transformed and it becomes a servant in avodas Hashem, and this is the most desirable and joyous path, hinted in the pasuk's wording of answering "in peace." Yet this only holds as long as the yetzer hara allows one to serve Hashem; if it utterly blocks avodas Hashem, a person must flee from it entirely, even departing from the balanced middle path. He grounds this in the pasuk that when a man's ways please Hashem even his enemies are reconciled, so before a person sins he can still be at peace with his yetzer. The Sfas Emes notes he later found this idea in the Ohr HaChaim.