The discussion of the Sotah [suspected adulteress wife] does not seem to fit into the basic topics of the opening chapters of the book of Bamidbar, which primarily deal with the topics of national import, primarily the size, roles and position of the respective Shevatim [the Tribes of Israel] in the Jewish nation at this point in history.
The Mikdash Mordechai explains that there is a very strong connection between the matter of the Sotah and the matter of the Shevatim: The linking factor is the concept of “Limishpechosam l’beis avosam” [according to their families, according to their father’s homes]. Here is a great nation, consisting of over 600,000 males of military age — and yet the Torah keeps on stressing over and over again the idea of “L’mishpechosam l’beis avosam” — that this nation and these tribes are all composed of family units. The idea is that Klal Yisroel as a whole is not stronger than those individual families. That is why the portion of Sotah is inserted here. The Torah is teaching us that when the basic family unit breaks down, eventually Klal Yisroel as a great nation breaks down as well. If there is not a secure family unit, then the result will be a suspected adulteress wife, and eventually the whole structure will collapse, since there is no L’mishpechosam l’beis avosam.
Using this concept, the Mikdash Mordechai then explains an interesting dispute we find in the Sifre [Halahic Midrash on the Books of Bamidbar & Devorim]. In the Torah, Sotah and Nazir are followed by Birkas Kohanim [the Priestly Blessing], which ends with the blessing “...v’yasem lecha Shalom” [...and He shall grant you Peace]. There is a dispute as to what this is referring to; Rav Chanina Segan haKohanim says this refers to peace in the home (Shalom Bayis). Rav Natan says this refers to peace on a national level (Shalom Malchus Beis Dovid). This seems to be a strange dispute with totally disparate opinions as to the nature of the Priestly Blessing.
The Mikdash Mordechai reconciles the two opinions and shows that the two sages are not arguing! Everyone agrees that the concern is for national peace — peace for Klal Yisroel. But in order to have peace for Klal Yisroel, two types of peace are necessary; peace with enemies on the borders, and peace at a national level. However, in order to achieve national peace, peace in the individual home is also a must. This huge, tremendous, Klal Yisroel is nothing more than a collection of family units and if the family unit is not secure, peace on a national level is not secure either.
