Wars Sent For Good
בפסוק כי תצא למלחמה כו' לא תירא מהם כו' ה"א עמך המעלך מא"מ כו' ה"א ההולך כו'
On the pasuk, "When you go out to war... do not be afraid of them... for Hashem your God is with you, who brought you up from the land of Mitzrayim... Hashem your God who goes [with you]" (Devarim 20:1-4).
The Sfas Emes opens with the parsha's pesukim about going out to war, where the Torah promises that Bnei Yisrael need not fear because Hashem who took them out of Mitzrayim is with them.
להלחם כו' פי' שכל המלחמות הבאים על עובדי ה' הם רק לטובה
"...to do battle" — the meaning is that all the wars that come upon those who serve Hashem are only for their good.
He establishes his central point: any war that befalls those who serve Hashem is ultimately only for their benefit.
והאות יצ"מ שע"י הגלות של מצרים זכו אח"כ לכל המדרגות וכן הוא לעולם
And the proof is Yetzias Mitzrayim, for through the galus of Mitzrayim Bnei Yisrael afterward merited all the levels [of kedushah], and so it is for all time.
He brings Yetzias Mitzrayim as the model — the very suffering of galus was what enabled Bnei Yisrael to rise to all the spiritual heights afterward, and this pattern holds in every generation.
וכתיב ההולך והל"ל הולך
And it is written "ha-holech" ("who goes"), whereas it should have said simply "holech" ("goes").
He notices a precise nuance in the wording: the Torah uses the form "ha-holech" rather than the plainer "holech," signaling a deeper message.
רק שבא לומר שכל המלחמה היא תהלוכות הבורא ית' לטובתינו להוציא בלעם מפיהם כדכתי' שלט האדם באדם לר"ל
Rather, it comes to teach that the entire war is the leading and guiding of the Borei Yisbarach for our good, to draw out the [hidden] good from within them, as it is written, "a man rules over a man to his own detriment" (Koheles 8:9) — meaning, to draw out [the good].
The added word teaches that the entire war is really Hashem's own guidance and orchestration on our behalf, meant to extract the hidden good buried within the conflict, as Koheles hints when one man's rule over another serves a deeper purpose.
וכ"כ ה' ילחם לכם הרמז כנ"ל שכל המלחמות של בנ"י ממנו ית' הם נשלחים לטובתינו
And so too it is written, "Hashem will fight for you" (Shemos 14:14) — the hint is as stated above, that all the wars of Bnei Yisrael are sent from Him, Yisbarach, for our good.
He ties this to the pasuk at Krias Yam Suf, "Hashem will fight for you," reinforcing that every war of Bnei Yisrael is dispatched by Hashem for our own good.
וז"ש תקום עלי מלחמה בזאת אני בוטח פי' במלחמה זו עצמה:
And this is what Dovid HaMelech meant: "Should war rise up against me, in this I trust" (Tehillim 27:3) — the explanation is, in this very war itself [I place my trust].
Finally he reads Dovid HaMelech's words in Tehillim to mean that his trust rests precisely within the war itself, knowing it is Hashem's doing for his benefit.
Summary: The Sfas Emes teaches that every war and struggle that comes upon those who serve Hashem is sent only for their ultimate good. He proves this from Yetzias Mitzrayim, where the very galus of Mitzrayim was the gateway through which Bnei Yisrael merited all their later spiritual levels, and he shows this remains true in every generation. Drawing on the precise wording "ha-holech," he explains that the entire war is in truth Hashem's own leading and orchestration, designed to draw out the hidden good concealed within the conflict, as reflected in the pasuk "Hashem will fight for you." He concludes with Dovid HaMelech's declaration in Tehillim that his trust rests within the very war itself, recognizing it as Hashem's doing for his benefit.