Rashi comments that the Torah is speaking about a milchemes reshus, discretionary war. With regard to milchemes mitzvah, a war which we are commanded to wage, such as against the sheva umos, seven pagan nations that inhabited Eretz Yisrael, we are enjoined not to take prisoners. Thus, the subsequent law regarding the yefas to’ar, beautiful captive, would not apply. The Baal Shem Tov also applies this pasuk as a metaphor for the never-ending battle we must wage against our internal enemy: the yetzer hora, evil inclination. We have no shortcuts in this battle. It is constant, so that it demands that we remain forever vigilant against subtle incursion or blatant attack. The obvious question is: How can the battle with the yetzer hora be considered discretionary? It is not the type of war during which we may rest or perhaps decide to skip this battle. It is constant and continuous, certainly not one we can describe as discretionary. A Jew is on a mission to sanctify Hashem’s Name in this world. As such, he is under Divine imperative to see to it that nothing impedes him from fulfilling his obligation.
The Kotzker Rebbe, zl, explains that the aspect of reshus, discretion, is not with regard to the battle, but rather, to the timing of the “attack.” One has the opportunity to initiate the battle, to take the offensive against the yetzer hora. If one waits until the battle has begun, and the yetzer hora has already taken captives, the battle is uphill and much more of a struggle. We must change our strategies, and alter our weaponry in order to fight effectively from a weaker vantage point. Therefore, the Torah writes, Ki seitzei, “When you will go out.” You must take the offensive and not dally until you have suffered casualties.
One does not wait until he has fallen into the abyss of sin before attempting to extricate himself from the clutches of the yetzer hora. At that point, it has become exceedingly difficult to emerge triumphant. Rather, when one notices a weakening in his imposed boundaries, a less-than- strict attitude to mitzvah performance, he should realize that the yetzer hora is preparing its first salvo. He must immediately act, lockdown his borders, and prepare to battle the yetzer hora before it establishes its footing. The individual must demarcate his “red line” and allow no incursion whatsoever. This is what the Torah means when it refers to a discretionary war. The individual calls the shots, not the enemy.
