Halakhah zu Bamidbar 27:21

And now I will begin mentioning each and every commandment, and I will explain their designation - as we set our goal at the beginning of our essay - for this is the intention of the book. Behold that I find it proper to add an addition to this intention: And that is that when I mention the commandment for which one receives a punishment - whether it be a positive or a negative commandment - I will mention its punishment. And I will say, "One who transgresses it will be liable for death, or excision, or a certain sacrifice, or lashes, or one of the death penalties of the court or payments." And you should know that that about which we do not mention any punishment: If it is a negative commandment, it is like that which they said, "It is like he is transgressing the commandment of the King," such that it is not for us to punish him. However with all positive commandments - whenever one is obligated to do one of them, we should give lashes to the one who refrains from doing it until he dies or does it. But if the time [for it] has passed, we refrain from this. Like, for instance, with one who transgressed and did not dwell in a sukkah - we do not give him lashes after Sukkot for his transgression. And know this. And also when I mention commandments for which women are not obligated - both positive and negative commandments - I will say this: "And women are not obligated in it." However it is well known that women do not judge, or testify, or bring sacrifices on their own or fight optional wars. So for all commandments that are contingent upon the court, or witnesses, or the Temple service or optional wars, I do not need to say, "And women are not obligated in this." For this [would be] extraneous speech and there is no need for it. Moreover, when I mention commandments that are only practiced in the Land of Israel or in the presence of the Temple - be they positive or negative commandments - I will say, "These are only obligated in the Land of Israel or in the presence of the Temple." However, it is also well known that all of the sacrifices are only done in the Temple and that the Temple service is only permitted in [its] courtyard; and likewise that capital punishments are only judged when the Temple is standing. And the language of the Mekhilta is, "From where [do we know] that we only sentence to death in the presence of the Temple? [Hence] we learn to say, 'from My altar you will take him to die' (Exodus 21:14) - behold, if you have the Temple you put him to death, if you don't have the Temple you do not put him to death." And there it also says, "From where do we know that the Sanhedrin needs to be close to the altar? As it is stated, 'from My altar.'" And it is also known that both prophecy and monarchy have departed from us until we refrain from our constant transgressions. And then He will atone for us and be merciful to us - as He set out - and bring them back, as it is stated (Joel 2:28), "And it will be after that, I will pour My spirit on all flesh, your sons and your daughters will prophesy." And regarding the return of the monarchy, He said, "On that day I will restore the fallen sukkah of David, and I will repair its breaches, etc., I will build it as in the days of old" (Amos 9:11). And it is well known that war and conquering of the cities cannot be without a king and without the counsel of the Great Sanhedrin and without a high priest, as it is stated (Numbers 27:21), "And he shall present himself in front of Elazar the Priest." And hence all of these are well-known to most people - all the positive or negative commandments that are contingent upon sacrifices, Temple rituals, capital punishments, the Sanhedrin, a prophet, a king or optional wars - so that I will not need to say about it, "This is only obligated in the presence of the Temple," since it is [already] clear, as we explained. But, with God's help, I will draw attention to that about which it is possible to have a doubt and about which some would err. And now I will begin the mentioning of each and every commandment of the Omnipresent.

The question of whether a preemptive war is included in the category of milḥemet mizvah or milḥemet reshut is crucial with regard to yet another aspect of Halakhah. The Mishnah, Sanhedrin 2a, stipulates that a discretionary war may be undertaken only upon the acquiescence of the Great Sanhedrin composed of seventy-one members. A subsequent Mishnah, Sanhedrin 20a, implies that a discretionary war may be undertaken only by a monarch. Thus, a discretionary war cannot be justified unless undertaken by the king⁴Ramban, addenda to Rambam’s Sefer ha-Miẓvot, miẓvot aseh, no. 4, states that the requirement that war be undertaken only by a king must be understood as including not only a monarch but any sovereign authority. Thus he states that war may be undertaken by “a king, a judge or whosoever exercises jurisdiction over the people.” For sources discussing Rambam’s possible disagreement regarding this point, see Contemporary Halakhic Problems, II, 207, note 27. with the permission of the Great Sanhedrin.⁵Rabbi Judah Gershuni, Torah she-be-‘al Peh, XIII (5731), 150f., advances the thesis that approval of the Sanhedrin is required only if the monarch finds it necessary to compel the populace to go to war and to conscript soldiers against their will, but that when the nation voluntarily agrees to go to battle approval of the Sanhedrin is not required. A similar view is advanced by Einayim la-Mishpat, Sanhedrin 16a. This view is supported by the comments of Me’iri, Sanhedrin 16a, who remarks that approval of the Sanhedrin is required in order to compel the populace to go out to battle. See also R. Abraham I. Kook, Mishpat Kohen, no. 145, and R. Saul Israeli, Amud ha-Yemini, no. 14 and no. 16, chap. 5, secs. 6-7. Cf., Amud ha-Yemini, no. 16, chap. 5, sec. 24. Moreover, in the context of a discussion of discretionary war, the Gemara, Berakhot 3b and Sanhedrin 16a, declares that the king may not undertake military action other than upon the approval of the urim ve-tumim.⁶Upon the twelve precious stones of the urim ve-tumim were engraved the names of the twelve tribes of Israel. In response to a specific query, various letters became illuminated. By means of the Divine Spirit the High Priest was enabled to combine the letters in order to discern the intended response.
Since no discretionary war could be undertaken other than upon approval of the urim ve-tumim, even discretionary war must be deemed to be undertaken with explicit divine approval and, conversely, no war could be undertaken other than with such divine sanction. Thus Abigail addresses King David and declares, “… for the Lord will certainly make a sure house for my lord because my lord fights the battles of the Lord” (I Samuel 25:28). Rambam, Hilkhot Melakhim 7:15, cites this verse and applies it to discretionary wars in stating:
Moreover, many ritual prohibitions are suspended even when discretionary wars are fought. Thus, once a discretionary war has been undertaken, it is permissible to wage such war on the Sabbath and combatants are permitted to partake of forbidden foods. The woman of “beautiful countenance” described in Deuteronomy 20:11 is permitted only to combatants engaged in discretionary wars but not to those engaged in commanded wars. It is thus clearly evident that even discretionary wars, when undertaken in accordance with the prescriptions of Halakhah, must be understood as undertaken by virtue of divine mandate. See Hilkhot Medinah, II, sha’ar 4, chapter 1, sec. 6. Indeed, Mekom Shmu’el, no. 8, suggests that the term “reshut” should be understood not as “permitted” or “discretionary” but as “licensed” or “sanctioned” in the sense that such war requires reshut Bet Din, i.e., sanction of the Sanhedrin, as distinct from wars that are obligatory by reason of explicit scriptural mandate. Although in Hilkhot Melakhim Rambam fails to mention consultation of the urim ve-tumim as a necessary precondition,⁷Cf., R. Yechiel Michael Epstein, Arukh ha-Shulḥan he-Atid, Hilkhot Mela-khim 74:7, who suggests that, even with regard to discretionary wars, consultation of the urim ve-tumim, although biblically mandated, is “perhaps” not a necessary condition of war. Although consultation of the urim ve-tumim constitutes a miẓvah and is required by virtue of biblical command, failure to engage in prior consultation, contends Arukh ha-Shulḥan he-Atid, does not affect the legitimacy of the war itself. See also, Le-Or ha-Halakhah, p. 12, and cf., Einayim la-Mishpat, Sanhedrin 16a. nevertheless, in the introduction to his Sefer ha-Mizvot, shoresh 14, Rambam does state that a High Priest is required for the undertaking of war; i.e., the king and the Sanhedrin may not undertake military action other than upon acquiescence of the urim ve-tumim which is attached to the breast-plate worn by the High Priest. Hence, absent a High Priest⁸See, however, Rambam’s reference to the function of the urim ve-tumim in Hilkhot Klei ha-Mikdash 10:11. who can consult the urim ve-tumim, offensive war in conformity with the stipulations of Jewish law is impossible. Ramban, in his addenda to Rambam's Sefer ha-Mizvot, mizvot lo ta'aseh, no. 17, declares that the requirement for consultation and approval of the urim ve-tumim is not limited to discretionary wars but applies with equal force to obligatory wars as well.⁹Rashi, in his commentary on the verse “and he shall stand before Eleazar the priest, who shall inquire for him by the decree of the Urim before the Lord” (Numbers 27:21), remarks that “even Joshua” was required to consult the urim ve-tumim “when he had need to go out to battle.” Since the wars of Joshua were all commanded wars, i.e., for the conquest of the territory inhabited by the Seven Nations, it must be inferred that Rashi agrees with Rambam in maintaining that consultation of the urim ve-tumim was necessary even in conjunction with commanded wars. See R. Judah Gershuni, Mishpat ha-Melukhah, Hilkhot Melak-him 5:2.
For a discussion of whether war against Amalek requires consultation of the urim ve-tumim, see R. Judah Gershuni, Torah she-be-‘al Peh, XIII (5731); cf., Contemporary Halakhic Problems, I, 16-18.