Shoftim תרל”א 3

שמע ישראל כו’ ברש”י אפי’ אין בכם רק זכות שמע ישראל כו’.
Before the nation went to war the kohen would say “Hear Yisrael you are coming to battle do not be afraid..” Rashi explains that even if the only merit we have is Shma Yisrael, that is meritorious enough through which we will be saved in battle.
פי’ להיות היחוד נקבע בהם שהכל רק מחיות השי”ת שזה פי’ ה’ א’
This means that the Oneness of HaShem should be so clear that one realises that everything is only from HaShem, there is no other existence asside from Him, which is the meaning of “HaShem is One”.
Therefore when we have that firmly idea firmly established in our mind when one goes to war…
ממילא אין שום ברי’ יכול להתנגד להאמת
Automatically nothing can withstand that truth and everything will be powerless over him (because one realises that everything is only the hand of HaShem).
וכל הכוחות מסט”א רק מחסרון אמונה. וידיעה זו בישראל.
For the only power that the negative force has, is from a lack of emuna and having this knowledge missing from us.
וזה עצמו יצ”מ ג”כ. שהראה הש”י לבנ”י שגם כח הסתר הגלות רק ממנו. וכמו שכתוב כחצות כו’ אני יוצא כו’ מצרים. אנא מתגלי.
This is also the concept of yitzias mitzrayim, that HaShem showed Bnei Yisrael that even the exile where there is a sewming hiddeness, it is also only from Him. As HaShem said “At midnight I will go out into Egypt” and Unkelos translates this to mean “I will be revealed”
כמ”ש במקום אחר.
As has been written in other place (Vayechi and Chanuka)
וכ”כ אם תקום כו’ מלחמה בזאת אני בוטח.
And similarly it says (Tehilim 27) “When the war arises against me This (בזאת) is what I trust in
ובזאת היא מ”ש להיות שאין שום דבר קיים רק בחיות השי”ת.
The word זאת this, means the above-mentioned idea, having the awareness that there is nothing exists without HaShem
והנקודה המנהגת הכל ממנו ית’ הוא הנק’ זאת כדפי’ אא”ז מו”ר ז”ל:
This point that guides the world is called זאת the refers to the 7 traits and א-ת refers to the whole Torah from beginning to end. As the Chidushei Harim explained.