Question

I wrote about an obligatory war. I concluded that this is an obligation on the king to compel, and not an obligation on the individual. What interests me is the discussion of the inference from the text. I would be happy if you would look it over and comment. I did not write about “do not stand idly by your neighbor’s blood.” Their blood is not more important than your blood. And it seems to me that the definition here of permission to take a risk is the nice inference from “for he sets his life upon it.” And that is the definition of hiring others, according to the view that says so.
 
Sotah 44a.
In an obligatory war
But in obligatory wars everyone goes out, even a groom from his room and a bride from her wedding canopy.
a0
A) Maimonides, Kings ch. 5
A king does not wage war first except an obligatory war. And what is an obligatory war? This is the war against the seven nations, and the war against Amalek, and helping Israel against an enemy that comes upon them, etc. It is a positive commandment to destroy the seven nations, etc., and likewise a positive commandment to erase the memory of Amalek. But regarding helping Israel, Maimonides did not bring a positive commandment. People have already tried to say that this is the commandment of “do not stand idly by your neighbor’s blood” and “you shall restore it to him.” But there one is not obligated, according to all views, to place himself in great danger, for there is an opinion that even the obligation to hire others is lighter than the obligation to endanger oneself. (Perhaps the degree of danger is like that learned from “for he sets his life upon it.”) And there is no need to elaborate on what others have already elaborated.
a0
And it seems that the obligation of an obligatory war applies only to the king.
That there are commandments incumbent on the king14see Yere’im (435, 299 in the old numbering), that the commandment to blot out the memory of Amalek is imposed on the king and not on the rest of Israel. And this is the meaning of the verse, “For a hand is on the throne of the Lord”that is, kingship; then the war of the Lord against Amalek will be fulfilled.
See Ketubot 17b: a king who waives his honor, his honor is not waived, for the Master said, “You shall surely set a king over yourself”that his awe should be upon you. And see Yoma 22b: Why was Saul punished (to come to the point that the kingship was taken from him, Rashi)? Because he waived his honor (when they disgraced him and he kept silent). Saul’s transgression was not “do not place a stumbling block,” in the sense that he caused the people to fail regarding the commandment of honoring the king; they belittled him on their own, as it says there: “But certain base fellows said…” and he kept silent. Rather, the commandment “You shall surely set” applies also to the king who is being appointed. The king must cause them to honor him.
The role of the king: see Maimonides, Kings 4:10: “A king is not appointed initially except to administer justice and wage wars,” as it says, “that our king may judge us and go out before us and fight our battles.” It follows that in the appointment, in the commandment “You shall surely set a king over yourself,” there is included an obligation to fight the wars of Israel.
a0(“You shall surely set” includes whatever is included in the “setting”granting the ability to act, and not the content of the acts. “That his awe should be upon you” may be a commandment also on the people, part of the appointment, whereas regarding the king the awe is part of the action, creating the ability to act…)
a0
C) The source of these laws in the text.
It appears that the meaning of “king” in the commandment “You shall surely set a king over yourself” (Deuteronomy 17) is a person with the powers that belonged to one called a king at the time the Torah was given. And see Sukkah 13a: “Hyssop,” etc.and not hyssop that has a qualifying name. Abaye said: Anything whose name changed before the giving of the Torah, and the Torah came and was particular about it, it is known that it has a qualifying name. Thus the meaning of a term is according to what it was at the time the Torah was given. And kings in the Torah’s time had unlimited authority.
What is said in the book of Joshua, “Whoever rebels against your command… shall be put to death,” is only a mere disclosure of what is already written in the Torah. (And what is expounded thereone might have thought even regarding matters of Torah, therefore Scripture says, “Only be strong and courageous”it seems that at the time the Torah was given there still were not yet matters of Torah in that sense, and the king’s authority was not limited, but in practice it did not include matters of Torah. There is a problem how to relate to the king’s powers: whether to understand “everything” as including matters of Torah, or to understand it according to the details that were in his authority, excluding matters of Torah. This was given by tradition, and it was clarified by the exposition in Joshua, even though it is a far-fetched exposition, as in every place where the text creates a problem. I already wrote some of this in Horayot 10a, section 7.)
a0
D) Maimonides, Kings 4:10, that “a king is not appointed initially except to administer justice and wage wars,” as it says, “that our king may judge us and go out before us and fight our battles.” This is not derived from what Israel did in Samuel’s time, for the beginning of their words there was, “that we too may be like all the nations.” Rather, what is mentioned there is the manner in which a king acts. It follows that this is included in “You shall surely set a king over yourself.” And therefore this is the king’s duty. And therefore, “a groom from his room and a bride from her wedding canopy”this is not the duty of the individual but the duty of the king.
Rabbi Soloveitchik’s lectures on Sanhedrin, edited by Rabbi Sasson
Sanhedrin 20b, section 59, page 266
And therefore they do not return, but regarding a war of helping Israel against an enemy, it would seem simple that it is only a law of war that applies to the community, and there is no personal obligation on the individual in this, and if so it should have been said that the law indeed applies