War of Mitzva and War of Reshut

This shiur originally appeared as a column in the weekly newsletter 'Shabbat MiTzion' of Torah Mitzion. 

Question:

When speaking of war, I often hear the terms milchemet (war of) mitzva and milchemet reshut (choice). Could you define what is categorized as milchemet mitzva, and what is milchemet reshut?

Answer:

The primary answer to your question can be found in the Rambam, Hilchot Melachim chapter 5 halacha 1, based on the Mishna and Gemara, Sotah 44b.

The Rambam defines milchemet mitzva as:

1. A war waged against the Seven Nations (those that were in Eretz Yisrael proceeding Yehoshua's conquering the land).

2. A war to wipe out Amalek.

3. A war fought to assist Israel from an enemy which attacks them.      

The Ramban (Nachmanides) in his comments to the Rambam's Sefer Hamitzvot, in the section of positive commandments the Rambam omitted, adds:

1. A war to conquer Eretz Yisrael from the hands of any non-Jewish nations who holds the land.

The Rambam defines a milchemet reshut as:

"A war fought with other nations in order to expand the borders of Israel or magnify its greatness and reputation."

Without analyzing all the details of each phrase that the Rambam uses, we can note several important points. This war is fought outside the borders of Eretz Yisrael. It is also not a war for the purpose of saving lives. It is a war for prosperity and benefit.

[In a later section we will touch on the obvious question of what is the status of the wars fought by the IDF today.]

Sources:

Talmud Sotah 44b, the Mishna and the corresponding section of Gemara

Talmud Berachot 3b story of David at end of page.

Rambam Hilchot Melachim u'Milchamot chapter 5 section1

Ramban comments on Rambam's Sefer Hamitzvot positive commandments the Rambam omitted, commandment 4.