Rabbi Shay Tahan
As part of writing my weekly newsletter and publishing articles on various news sites, when the war started, I looked into our sources to see what halacha writes about such events. To my surprise, I didn't find any sefarim that gather all those halachot and ideas. Therefore, I had to independently draw from early sources such as the Torah itself, the Gemara, Midrashim, and Rishonim.
Indeed, in the Torah itself, wars are mentioned multiple times, and there are parashot that deal at length with the mitzvot involving wars. For example, the Torah explains who goes to fight a war, exempting those who are recently engaged and soon getting married, or those who have built a new house but have not yet lived in it. It also exempts those who have planted a field and have not yet eaten from it.
Furthermore, the Torah explains how the mashuach milchama (anointed priest who addresses the warriors) should speak to the soldiers and the mitzvah of how one should clean himself at the war zone. The Torah also teaches us how to overcome fear during war and what techniques the enemy uses to instill fear in us.
Still, these important laws and their implications seem to not have made it into the basic halacha sefarim such as the Shulchan Aruch and later poskim, and we should wonder why (Although the Rambam expounded on some of those laws). Regarding the Shulchan Aruch, we can refer to the words of its author, Rav Yosef Karo, in his work the Bet Yosef. He explained that it could very well be that the poskim didn't delve into this deeply, as Jews didn't participate in wars throughout the lengthy exile of two thousand years. The Beit Yosef comments on the Tur(או״ח סימן רמט) , who mentioned the laws of going to war, and said that he shouldn't have brought down those matters as they aren't relevant since Jews didn't go to fight wars.
Unfortunately, the matters of going to fight wars are relevant once again. As the Bach explains, the Tur mentioned wars to teach us for times when Jewish people are kidnapped; it becomes a mitzvah war to go and fight to bring them back.
Thus, as I continued writing about these matters on a weekly basis, the articles began to accumulate. I decided that it might be beneficial for the public to have a sefer that compiles all of these writings.
The sefer could be a source of guidance not only for those involved in the war but also for every Jew around the world for two reasons. Firstly, recent wars have shown every Jew around the globe that war isn't just for those who live in Israel but rather for every Jew, even those in distant corners of the world. Secondly, it provides guidance on how one should feel during such times, including strengthening their emunah and bitachon.
